Relationship among cattle breed and anabolic implant protocol relative to feedlot performance: Growth, temperament, feeding behavior, carcass traits, and economic return

Recent research has suggested that different cattle breed types may respond differently to anabolic implant protocols of varying intensity. Therefore, the purpose of this research was to compare anabolic implant protocols in feedlot steers of 2 different breed types. Sixty steers were stratified by weight and breed in a 2 × 3 factorial design examining 2 different breeds: Angus (AN; n=38) or Santa Gertrudis influenced (SG; n=22), and 3 implant strategies: no implant (CON; n=20), a moderate intensity implant protocol (d0 implant: Revalor-G, d56 implant: Revalor-IS, d112 implant: Revalor-S; MI; n=20), or a high intensity implant protocol (d0 implant: Revalor-IS, d56 implant: Revalor-S, d112 implant: Revalor-200; HI; n=20). Steers were randomly placed into pens equipped with GrowSafe bunks to collect dry matter intake and feeding behavior. All animals were fed the same diet. Weight, chute score, exit velocity, serum, rectal temperature, hip height and 12th rib fat thickness were collected approximately every 28 d over a 196 d period. Serum urea nitrogen (SUN) was evaluated as well. Total average daily gain was increased (P < 0.0001) in both the HI and MI steers compared to the CON steers by 29.4% and 26%, respectively. A treatment × breed interaction was observed (P < 0.0001) for hip height, with AN-CON steers being shorter (P < 0.0007) than AN-HI, SG-CON, SG-MI, and SG-HI steers. A breed × treatment interaction was observed (P < 0.004) for chute score and rectal temperature, with SG-HI and SG-MI steers having increased chute scores (P < 0.001) when compared to AN-HI, AN-MI, AN-CON, and SG-CON throughout the course of the trial. Additionally, SG-HI and SG-MI steers had an increased rectal temperature (P < 0.004) compared to AN-HI, AN-MI, AN-CON, and SG-CON steers. A breed effect was observed (P = 0.002) for SUN with AN steers having increased (P = 0.002) SUN concentration compared to SG sired steers, in addition to a treatment effect (P < 0.0001), with CON steers having a higher (P < 0.0001) SUN concentration than MI and HI steers, regardless of breed. The MI implant protocol increased net return per head, on average, by $97.28, regardless of breed, while the HI implant protocol increased net return by only $80.84. Taken together, despite the cattle breed types responding differently to the different anabolic implant protocols at times, a moderate intensity anabolic implant protocol was optimal in this experiment for steers raised in a temperate climate.

Crystal Structure of the Commercial Herbicide, Amidosulfuron, in Complex with Arabidopsis thaliana Acetohydroxyacid Synthase

Amidosulfuron (AS) is from the commercial sulfonylurea herbicide family. It is highly effective against dicot broad-leaf weeds. This herbicide targets acetohydroxyacid synthase (AHAS), the first enzyme in the branched chain amino acid biosynthesis pathway. Here, we have determined the crystal structure of AS in complex with wildtype Arabidopsis thaliana AHAS (AtAHAS) and with the resistance mutant, S653T. In both structures, the cofactor, ThDP, is modified to a peracetate adduct, consistent with time-dependent accumulative inhibition. Compared to other AHAS-inhibiting herbicides of the sulfonylurea family, AS lacks a second aromatic ring. The replacement is an aryl sulfonyl group with a reduced number of interactions with the enzyme and relatively low affinity (K_i = 4.2 μM vs low nM when two heteroaromatic rings are present). This study shows that effective herbicides can have a relatively high K_i for plant AHAS but can still be a potent herbicide provided accumulative inhibition also occurs.

Degradation of PET Bottles by an Engineered Ideonella sakaiensis PETase

Extensive plastic production has become a serious environmental and health problem due to the lack of efficient treatment of plastic waste. Polyethylene terephthalate (PET) is one of the most used polymers and is accumulating in landfills or elsewhere in nature at alarming rates. In recent years, enzymatic degradation of PET by Ideonella sakaiensis PETase (IsPETase), a cutinase-like enzyme, has emerged as a promising strategy to completely depolymerize this polymer into its building blocks. Here, inspired by the architecture of cutinases and lipases homologous to IsPETase and using 3D structure information of the enzyme, we rationally designed three mutations in IsPETase active site for enhancing its PET-degrading activity. In particular, the S238Y mutant, located nearby the catalytic triad, showed a degradation activity increased by 3.3-fold in comparison to the wild-type enzyme. Importantly, this structural modification favoured the function of the enzyme in breaking down highly crystallized (~31%) PET, which is found in commercial soft drink bottles. In addition, microscopical analysis of enzyme-treated PET samples showed that IsPETase acts better when the smooth surface of highly crystalline PET is altered by mechanical stress. These results represent important progress in the accomplishment of a sustainable and complete degradation of PET pollution.

Triazolopyrimidine herbicides are potent inhibitors of Aspergillus fumigatus acetohydroxyacid synthase and potential antifungal drug leads

Aspergillus fumigatus is a fungal pathogen whose effects can be debilitating and potentially fatal in immunocompromised patients. Current drug treatment options for this infectious disease are limited to just a few choices (e.g. voriconazole and amphotericin B) and these themselves have limitations due to potentially adverse side effects. Furthermore, the likelihood of the development of resistance to these current drugs is ever present. Thus, new treatment options are needed for this infection. A new potential antifungal drug target is acetohydroxyacid synthase (AHAS; EC 2.2.1.6), the first enzyme in the branched chain amino acid biosynthesis pathway, and a target for many commercial herbicides. In this study, we have expressed, purified and characterised the catalytic subunit of AHAS from A. fumigatus and determined the inhibition constants for several known herbicides. The most potent of these, penoxsulam and metosulam, have K_i values of 1.8 ± 0.9 nM and 1.4 ± 0.2 nM, respectively. Molecular modelling shows that these compounds are likely to bind into the herbicide binding pocket in a mode similar to Candida albicans AHAS. We have also shown that these two compounds inhibit A. fumigatus growth at a concentration of 25 µg/mL. Thus, AHAS inhibitors are promising leads for the development of new anti-aspergillosis therapeutics.

Structures of fungal and plant acetohydroxyacid synthases

Acetohydroxyacid synthase (AHAS), also known as acetolactate synthase, is a flavin adenine dinucleotide-, thiamine diphosphate- and magnesium-dependent enzyme that catalyses the first step in the biosynthesis of branched-chain amino acids¹. It is the target for more than 50 commercial herbicides². AHAS requires both catalytic and regulatory subunits for maximal activity and functionality. Here we describe structures of the hexadecameric AHAS complexes of Saccharomyces cerevisiae and dodecameric AHAS complexes of Arabidopsis thaliana. We found that the regulatory subunits of these AHAS complexes form a core to which the catalytic subunit dimers are attached, adopting the shape of a Maltese cross. The structures show how the catalytic and regulatory subunits communicate with each other to provide a pathway for activation and for feedback inhibition by branched-chain amino acids. We also show that the AHAS complex of Mycobacterium tuberculosis adopts a similar structure, thus demonstrating that the overall AHAS architecture is conserved across kingdoms.

The Role of a FAD Cofactor in the Regulation of Acetohydroxyacid Synthase by Redox Signaling Molecules

Acetohydroxyacid synthase (AHAS) catalyzes the first step of branched-chain amino acid (BCAA) biosynthesis, a pathway essential to the lifecycle of plants and microorganisms. This enzyme is of high interest because its inhibition is at the base of the exceptional potency of herbicides and potentially a target for the discovery of new antimicrobial drugs. The enzyme has conserved attributes from its predicted ancestor, pyruvate oxidase, such as a ubiquinone-binding site and the requirement for FAD as cofactor. Here, we show that these requirements are linked to the regulation of AHAS, in relationship to its anabolic function. Using various soluble quinone derivatives (e.g. ubiquinones), we reveal a new path of down-regulation of AHAS activity involving inhibition by oxidized redox-signaling molecules. The inhibition process relies on two factors specific to AHAS: (i) the requirement of a reduced FAD cofactor for the enzyme to be active and (ii) a characteristic slow rate of FAD reduction by the pyruvate oxidase side reaction of the enzyme. The mechanism of inhibition involves the oxidation of the FAD cofactor, leading to a time-dependent inhibition of AHAS correlated with the slow process of FAD re-reduction. The existence and conservation of such a complex mechanism suggests that the redox level of the environment regulates the BCAA biosynthesis pathway. This mode of regulation appears to be the foundation of the inhibitory activity of many of the commercial herbicides that target AHAS.

Identification of SNPs located on BTA 6 and BTA 20 significantly associated with bovine respiratory disease in crossbred cattle

The objective of the present study was to evaluate single nucleotide polymorphisms (SNPs) located in two quantitative trait locus (QTL) regions (BTA 6 and BTA 20) that are associated with bovine respiratory disease (BRD). A population of 323 crossbred steers sired by five purebred sire breeds during 2010-2013 (Angus, Braford, Braunvieh, Charolais, and Simmental) were evaluated for BRD susceptibility during the finishing process at a commercial feedlot. A total of 21 animals representing all sire breeds were affected with BRD at some time during the finishing process over the 4-year period. Although multiple sire breeds were evaluated in the present study, no sire breed effects were detected. A total of 82 SNPs were evaluated (58 on BTA 6 and 24 on BTA 20) in the present study for potential associations with BRD incidence. When evaluating the previously described QTL regions on BTA 6, three SNPs (rs42968895, rs42823614, and rs43448463) were significantly (P < 0.05) associated with BRD incidence. Another three SNPs (rs42477340, rs42512588, and rs42524468) were identified as significantly associated with BRD on the previously described BTA 6 QTL region. For both of these regions, animals inheriting different genotypes differed in BRD incidence during the finishing period. Although multiple SNPs were identified as being significantly associated with BRD incidence in the present study, these SNP associations should be validated in larger and more diverse populations.

Single nucleotide polymorphisms associated with carcass traits in a population of Brahman and Brahman-influenced steers

Brahman cattle are important in tropical regions due to their ability to tolerate excessive heat and parasites. However, Brahman cattle exhibit lower carcass quality characteristics when compared to Bos taurus breeds. The objective of this study was to evaluate potential associations between single nucleotide polymorphisms (SNPs) in six candidate genes for carcass quality and composition traits in a population of Brahman and Brahman-influenced steers. Steers were evaluated through the American Brahman Breeders Association carcass evaluation project in Gonzales, Texas. Carcass traits measured included hot carcass weight, ribeye area, marbling score, yield grade, quality grade, dressing percent, and Warner-Bratzler shear force score. Six previously described candidate genes were chosen for SNP analysis based on their previous association with growth and carcass traits. Candidate genes utilized in the current study included calpastatin (CAST), calpain (CAPN3), thyroglobulin (TG), growth hormone, insulin growth factor 1, and adiponectin. Six unique SNPs from three candidate genes (TG, CAST, and CAPN3) were significantly associated (P < 0.001) with carcass quality traits (marbling score and quality grade). A genotypic effect was observed for all significant SNPs, with differing levels of performance observed for animals inheriting different genotypes. Although multiple SNPs in the current study were significantly (P < 0.001) associated with growth and carcass traits, they should be validated in larger populations prior to implementation in selection strategies.

Antioxidant and cytotoxic activities of Sideritis perezlarae (Borja) Roselló, Stübing and Peris

Sideritis perezlarae is a plant widely used in folk medicine in the South of Andalusia (Cádiz, Spain). In this work, a phytochemical analysis has led to the isolation and identification of the flavonoid 7-O- β -glucosyl-luteolin from a methanol extract. The total phenol content estimated by Folin-Ciocalteau assay and expressed as gallic acid equivalent per gram of dried fraction, was 102.54 ± 2.10 mg phenols per gram dry residue. The flavonoid content, investigated by AlCl3 reagent, was 23.49 ± 0.90 mg flavonoids gram dry residue. The methanol extract has been evaluated for antioxidant (DPPH and TEAC assays) and cytotoxic (SRB assay) properties. In the DPPH radical scavenging assay, the IC50 was 360 µg mL(-1). In the total antioxidant activity, calculated by the Trolox equivalent antioxidant activity (TEAC, mg g(-1) of dried fraction), the extract showed a high antioxidant capacity (TEAC value of 0.59 ± 0.02 mg g(-1)). The cytotoxic activity of the extract against a human adenocarcinoma cell line HT-29 presented an IC50 = 69.47 ± 4.64 µg mL(-1).

Topical anti-inflammatory effect of tirucallol, a triterpene isolated from Euphorbia lactea latex

Latex from Euphorbia lactea (Euphorbiaceae), a native Dominican medicinal plant, is claimed to be useful in the treatment of inflammation. Topical application of tirucallol, a tetracyclic triterpene isolated from Euphorbia lacteal latex, suppressed ear edema in the mouse model in a dose-dependent manner, as well as affecting the influx of polymorphonuclear cells in response to topical application of 12-O-tetradecanoylphorbol-acetate (TPA) in the mouse ear. In addition, the effect of tirucallol, on some macrophage functions was analyzed in vitro. Non-toxic concentrations of tirucallol potently inhibited nitrite production in lipopolysaccharide-stimulated macrophages. Western blot analysis showed that nitric oxide reduction was a consequence of the inhibition of inducible nitric oxide synthetase expression although tirucallol slightly affected to prostaglandin E(2) (PGE(2)) generation. The results of the study revealed that tirucallol (0.3%), present in Euphorbia lactea latex, exerts a topical anti-inflammatory effect in vivo, via a mechanism of action related to the neutrophil migration. On the other hand, it can be deduced that the mechanism of the anti-inflammatory activity of this triterpene is related to the control of the production of NO and its effect on the expression of iNOS.

Dynamics of GHRH in third-ventricle cerebrospinal fluid of cattle: relationship with serum concentrations of GH and responses to appetite-regulating peptides

Objectives were to (1) characterize the relationship of third-ventricle (IIIV) cerebrospinal fluid (CSF) concentrations of growth hormone-releasing hormone (GHRH) with concentrations of GH in the peripheral circulation; and (2) assess the influence of acute administration of appetite-regulating peptides leptin (anti-orexigenic) and neuropeptide Y (NPY; orexigenic) on the release of GHRH. Six mature beef cows fitted with IIIV and jugular vein cannulae were treated intracerebroventricularly with saline, and leptin (600 microg) and NPY (500 microg) in saline, in a replicated 3x3 Latin square design. Third-ventricle CSF and blood were collected 10 min before and continued 220 min after treatments. Mean concentrations of GHRH and frequency of pulses after treatments were 2.2+/-0.13 ng/mL and 1.2+/-0.15 pulses/220 min, respectively. These measures were not influenced by treatments. Concentrations of GHRH in CSF were weakly correlated (r=0.15; P<0.03) with serum concentrations of GH; however, 58% of the GH pulses were preceded by a pulse of GHRH and 90% of the GHRH pulses occurred within 20 min preceding a pulse of GH. Leptin tended (P<0.10) to suppress GH area under the curve (AUC) compared to saline. Concomitantly, NPY tended (P<0.10) to increase GH AUC, which appeared to be a consequence of increased (P<0.05) pulse amplitude. Infusion of NPY also increased (P<0.05) AUC of GHRH relative to saline. No differences were detected among treatments in serum concentrations of insulin-like growth factor-I or its AUC. Sampling CSF from the IIIV appears to be a viable procedure for assessing hypothalamic release of GHRH coincident with anterior pituitary gland secretion of GH in cattle. These data also demonstrate the differential responsiveness of the GH axis to appetite-regulating peptides.

Associations of DNA polymorphisms in growth hormone and its transcriptional regulators with growth and carcass traits in two populations of Brangus bulls

Sequence polymorphisms in the growth hormone (GH) gene and its transcriptional regulators, Pit-1 and Prop-1, were evaluated for associations with growth and carcass traits in two populations of Brangus bulls Chihuahuan Desert Rangeland Research Center (CDRRC, N = 248 from 14 sires) and a cooperating breeding program (COOP, N = 186 from 34 sires). Polymorphisms were SNP mutations in intron 4 (C/T) and exon V (C/G) in GH, A/G in exon VI in Pit-1, and A/G in exon III in Prop-1. In the COOP population, bulls of Pit-1 GG genotype had a significantly greater percentage of intramuscular fat than bulls of the AA or AG genotype, and bulls of the Prop-1 AA genotype had significantly greater scrotal circumference than bulls of AG or GG genotypes at ~365 days of age. Also, heterozygous genotypes for the two GH polymorphisms appeared advantageous for traits of muscularity and adiposity in the COOP population. The heterozygous genotype of GH intron 4 SNP was associated with advantages in weight gain, scrotal circumference, and fat thickness in the CDRRC population. The two GH polymorphisms accounted for >/=27.7% of the variation in these traits in the CDRRC population; however, R(2) was <5% in the COOP population. Based on haplotype analyses the two GH SNPs appeared to be in phase; the haplotype analyses also paralleled with the genotype analyses. Polymorphisms in GH and its transcriptional regulators appear to be predictors of growth and carcass traits in Brangus bulls, particularly those with heterozygous GH genotypes.

Antimicrobial activity and phytochemical studies of some lichens from south of Spain

The antimicrobial activity of some lichens from south Spain has been studied and some of plant constituents were identified. Activity against some Gram (+) bacteria has been observed in lichens containing usnic acid.

An independent confirmation of a quantitative trait locus for milk yield and composition traits on bovine chromosome 26

Several reports have demonstrated that bovine chromosome 26 (BTA26) harbours significant or suggestive quantitative trait loci (QTL) for milk production and composition traits in dairy cattle. Our previous study showed that a C/T substitution in the bovine TCF7L2 gene on BTA26 was significantly linked to QTL for protein yield (PY) in a Canadian dairy cattle population. Actually, this polymorphism was one of the markers derived from a genome-wide screening of QTL for milk PY using an amplified fragment length polymorphism technique combined with a DNA pooling strategy. In the present study, 990 Holstein bulls with complete genotype and phenotype data from 14 sire families were analysed to confirm, if the QTL effects exist in other populations. Statistical analysis revealed that this marker was significantly associated with PY, protein percentage, milk yield and fat yield (FY) (p < 0.001) in the US Holstein population. These results indicate that this QTL region has a pleiotrophic effecton different milk traits and is portable in different populations.

Metabolic characteristics of multiparous Angus and Brahman cows grazing in the Chihuahuan Desert

Understanding metabolic differences between breeds of cattle is important when selecting for production in semiarid environments. Spring-calving multiparous Angus and Brahman cows (n = 8/breed) grazing in the Chihuahuan Desert were used to evaluate metabolic hormone status in February (i.e., 3rd trimester of pregnancy), May (i.e., early lactation), and September (i.e., late lactation) 2000. Crude protein in ruminal digesta collected from grazing companion ruminally cannulated cows during these months was 5.6, 6.0, and 10.3%, respectively. Angus cows were heavier (P < 0.01) than Brahman cows across months. Body condition scores among breed groups were 4.4, 3.6, and 4.6 in February, May, and September with Brahman cows tending (P < 0.10) to have greater body condition than Angus cows in May. Brahman cows tended to have greater fecal output per 100 kg BW than Angus cows in February (0.9 > 0.7 +/- 0.1, P < 0.10). Brahman cows had greater serum concentrations of leptin than Angus cows in September (1.8 > 0.70 +/- 0.1 ng/mL; P < 0.05), and serum concentrations of insulin were greater (P < 0.01) in Brahman than Angus cows throughout the study. Brahman cows also had greater (P < 0.01) serum concentrations of glucose during February and May than Angus cows. Serum concentrations of triiodothyronine were greatest (P < 0.01) during September and lowest during February and May in both breed groups and were greater (P < 0.01) in Brahman than in Angus cows in February, May, and September. Pregnancy rate and 205-d adjusted weaning weights were similar (P > or = 0.46) among breed groups. Results suggest that Brahman and Angus cows are sensitive to the seasonal dynamics of forage quality in the Chihuahuan Desert. Brahman cattle appear to have greater concentrations of metabolic hormones and metabolites than Angus cows in this environment, but Angus cows experience greater fluctuations in BW.

Cytotoxic activity of Agave intermixta L. (Agavaceae) and Cissus sicyoides L. (Vitaceae)

The cytostatic activities of Agave intermixta L. (Agavaceae) and Cissus sicyoides L. (Vitaceae) have been determined. In the antimitotic assay, Agave intermixta L. showed complete inhibition of cell division at 24 h of treatment. Both species showed a moderate cytostatic activity against HEp-2 cells, Cissus sicyoides L. being the most active species.

Polyphasic taxonomy of a novel yeast isolated from antarctic environment; description of Cryptococcus victoriae sp. nov

In 1992 some samples of mosses, lichens and soils were collected from Botany Bay, Southern Victoria Land (77 degrees 01' S 162 degrees 32' E) and, as a result of a routine screening programme some yeasts were isolated. One of them, designated as strain G5, showed marked differences when compared to other antarctic yeasts. According to morphological and physiological characteristics, we were able to identify the strain G5 as a yeast belonging to the genus Cryptococcus. Some characteristics of this genus are the growth response to myo-inositol, celobiose, raffinose and D-glucuronate, no-fermentation, the absence of mycelium and pseudomycelium, asexual reproduction, Diazolium blue B test (DBB) and urea hydrolisis positive and the growth without vitamines. This strain (G5) formed cream colonies of slimy appearance with cells of 3 x 2 microns in size, that grew between 4 degrees C and 20 degrees C. The G + C content of strain G5 was 50.3 mol%. The molecular characterization by whole-cell proteins and RFLP analysis of the 5.8S rRNA gene and the two ribosomal internal transcribed spacers (5.85-ITS region), revealed that this strain was different from other antarctic species of this genus. The phylogenetic tree deduced from the 5.8S rRNA gene sequence showed the strain G5 as a member of the genus Cryptococcus, clearly separated from other basidiomycetous yeasts. On the basis of the physiological, genotypical and phylogenetical data, the new isolate G5 was described as Cryptococcus victoriae, sp. nov., with the type strain G5 (= CECT 11114).

Cytostatic activity of some compounds from the unsaponifiable fraction obtained from virgin olive oil

Oleuropein, tyrosol, squalene and the fraction of sterols and triterpenoid dialcohols from the unsaponifiable fraction obtained from virgin olive oil have been tested for possible cytostatic activity against McCoy cells, using 6-mercaptopurine as a positive control. The samples of sterols and triterpenic dialcohols showed a strong activity.

Effect of dietary phytosterols on rat tissue lipids

The present study was designed to examine the incorporation of phytosterols (PS) in membranes and tissues of rats fed a diet containing 2% PS in the presence of 0.2% cholic acid for 22 days. The control diet contained 12 mg PS/100 g compared with 2,012 mg/100 g. Liver, kidney, testis, and prostate microsomes, plasma, and epididymal fat pads were examined for sterols. Fatty acid composition and phospholipid pattern were also examined in some tissues. The PS diet resulted in a fivefold increase in plasma PS compared with controls. PS was found to accumulate in adipose tissue and liver microsomes in rats fed the PS-supplemented diet. There was no effect of PS incorporation on microsomal cholesterol content, except in the testes, in which dietary PS reduced cholesterol content by 25%. Dietary PS increased 20:4n-6 and 22:5n-3 fatty acids in membranes of the liver, testis, and prostate but decreased 16:1 in liver microsomes. PS incorporation had no effect on the phospholipid pattern of the liver and testis.

Almost total absence of the left ventricular myocardium with dextro-transposition of the great arteries

The term parchment heart is used to describe partial to nearly complete loss of ventricular myocardium. We report the first case of transposition of the great arteries with almost total absence of left ventricular myocardium. The latter was not recognized and the child underwent Mustard's operation at four months of age. He died on the operating table. At necropsy, the left ventricular wall was 1 mm in thickness; microscopic examination revealed few myocardial fibers within edematous connective tissue.

[Aberrant left pulmonary artery and acute respiratory insufficiency in infants]

The aberrant left pulmonary artery is a rare disease, producing severe respiratory failure in the neonatal period and early infancy. The diagnosis is easy and mainly done by X-ray. Although the main diagnostic procedure continues to be an elective angiography in the main pulmonary artery, the diagnosis may be confirmed by a contrast computerised axial tomography. It is necessary to use the classic tomography to rule out any associated tracheobronchial anomalies, and thus avoid other dangerous diagnostic procedures such as bronchoscopy and bronchography. Having reviewed previous publications, two cases are presented, one, being exceptional with left lung emphysema.

Plasma and pituitary thyrotrophin (TSH) in severe and prolonged hypothyroidism, as studied in the rat

Thyroidectomized rats, kept on a low iodine diet, were killed at 60, 80 and 270 days after thyroidectomy and plasma and pituitary TSH levels measured. Pituitary TSH content was lowere in the thyroidectomized rats than in the controls at 60 and 80 days, starting to increase between 60 and 80 days, and reaching higher values than those of the controls by 270 days. Plasma TSH was higher in the thyroidectomized rats than in the controls at all the times studied, but declined markedly between 60 days (17.53 +/-1.98 mug/ml) and 270 days (3.63 +/-0.49 mug/ml. This decrease in plasma TSH levels was accompanied by a decrease in plasma PBI: from 0.69+/-0.08 mug/dl at 60 days to 0.06+/-0.01 mug/dl at 270 days. The daily injection of 1.75 mug T4/100 g body weight for 12 days in either thyroidectomized rats or normal intact rats resulted in a decline of plasma TSH levels in both groups. Pituitary TSH content increased in the thyroidectomized rats and decreased in the controls after T4 treatment. Present results agree with previous observations indicating that severe and chronic thyroid hormone deficiency is not accompanied by a progressive increase in circulating TSH levels, though an elevation is always fou nd even in mild or subclinical forms or primary hypothyroidism. They show that in the rat this connot be accounted for by an impairment of TSH synthesis, as previosly suggested: an impairment of TSH secretion appears more probable.

Decreased pituitary growth hormone content in rats treated neonatally with high doses of L-thyroxine

Growth hormone and thyrotrophic hormone content have been measured by specific radioimmunoassays in anterior pituitaries of 22 day old rats. These animals were injected with saline or very high doses of L-thyroxine during the neonatal period in order to induce the "neo-T4" syndrome. Growth of such animals is known to be affected. It was found that not only TSH but also GH content of the T4-treated animals was significantly lower than that of the saline-injected controls.

[Validation of the radioimmunoassays for pituitary gonadotropins II. Human follicle stimulating hormone (author's transl)]

The present paper summarizes the experience of the authors in the setting up of the radioimmunoassay (RIA) for human follicle simulating hormone (H-FSH), with the purified antigen for radioiodination, the F-FSH standard and the specific antibodies kindly donated by the National Pituitary Agency of the National Institutes for Arthritis, Metabolic and Digestive Diseases of the National Institutes of Health, Bethesda, MD. U.S.A. The conditions for the RIA have modified somewhat and simplified with respect to the suggested instructions accompanying the reagents. Thus, the amount of Chloramine T and the time of exposure of the labeled H-FSH (H-FSH) has been studied. It is always purified on Sephadex G-100 immediately before addition to the RIA and in this manner it may be used for up to 2 month after labeling when kept at --20 degrees C. Curves obtained at different dilutions of the H-FSH Standard, carried out with phosphosaline buffer, pH 7.4-7.8 (PBS) containing 1 % human serum albumin, or with horse plasma, of with PBS containing 0,25 % serum from non-immune rabbits (RIA Buffer) have been compared iwth those abtained by serial dilutions of sera from post-menopausal with these diluents. The most consistent results were obtained with the RIA buffer as diluent. The redisual error was smaller, and serial of dilution curves of the H-FSH standard were parallel to those of plasma and acetone precipitates of urine from post-menopausal women. Parallelism was not god using those serum. Results using PBS contianing human seum albumin were poor. PBS containing bovine serum albumin was avoided as some batches were found to interfere with the binding of the F-FSH to the antibody. The stability of the different dilutions of the H-FSH standard prepared in RIA buffer was tested. It was found that the standard curves could be prepared, pipetted into the RIA tubes and kept ready, frozen at --20 degrees C for one to two months. This shortens the actual setting up of a given RIA and decreases interassay variation of results. Parallelism of the H-FSH standard curve with serial dilutions (in RIA-buffer) of sera from women on the day of the preovulatory was confirmed. The data obtained in men and women, during stimulation with LH-RH are also given. No cross reactivity was found the HCG or sera from women, in agreement with the fact that the antiserum had been absorbed with HCG. There is, however, a considerable degree of cross reactivity with H-TSH; Thus, sera containing 15 muU/ml H-TSH or more, would give false H-FSH results. Such H-TSH values are not only found in hypothyroid patients, but might be reached during TRH responses to TRH.

Effects of adrenalectomy and corticosterone on thyroid weight of goitrogen-treated rats. Role of adrenal-corticoids in the insulin increase of goitre weight

The administration of insulin to intact rats on a low iodine diet (LID) and KClO4, or KClO4 as well as 6-propyl-2-thiouracil (PTU) increases the weights of the thyroid significantly, as compared to rats on goitrogens alone.

However, as shown here, insulin treatment has no effect on the weights of the thyroid of adrenalectomized goitrogen-treated animals. Furthermore, in adrenalectomized rats on small doses of corticosterone the administration of insulin does not alter the weight of the goitre induced by KClO4. On the other hand, adrenalectomized rats on PTU, or KClO4, or PTU + KClO4 develop smaller goitres than intact animals.

The administration of corticosterone increases the thyroid weights of intact rats on goitrogens, and augments the weights of the goitres of adrenalectomized rats on PTU to the values found for intact rats on the same goitrogen. The above mentioned changes in thyroid weight cannot usually be accounted for by changes in circulating TSH, as assessed by a rat TSH radioimmunoassay.

The present results are consistent with the assumption that the adrenals probably via corticosterone secretion, play an important role in the mechanism by which insulin increases the weight of the thyroid glands of rats on LID + KClO4, or LID + KClO4 + PTU, without affecting the high plasma TSH levels.

Induction of goitre by PTU or KCIO4 in male and female rats. Effect of gonadectomy

Male and female rats of varying ages were placad on a low iodine diet (LID) plus KClO4 or 6-propyl-2-thiouracil (PTU) or on the same diet supplemented with I (control rats). Goitrogenesis was also induced with LID plus PTU in gonadectomized animals of both sexes. The weight of the control and goitrogen treated animals, and the weight and iodine content of their thyroids were determined, as well as the plasma PBI, TSH, insulin and glucose levels. The pituitary GH-like protein content was assessed by disc electrophoresis on polyacrylamide gels.

If goitrogenesis was induced in young rats of both sexes starting with rats of the same age, body weight (B.W.) and pituitary growth hormone (GH) content, it was found that both the males and females developed goitres of the same size. On the contrary, when goitrogenesis was induced in adult animals, it was found that male rats, that had larger B.W. and pituitary GH content than age-paired females, developed larger goitres. However, both male and female rats were in a hypothyroid condition of comparable degree as judged by the thyroidal iodine content and the plasma PBI and TSH levels.

When all the data on the PTU or KClO4-treated male and female rats of varying age and B.W. were considered together, it was observed that the weights of the thyroids increased proportionally to B.W. However, a difference in the slope of the regression of the thyroid weight over B.W. was found between male and female rats, due to the fact that adult male rats develop larger goitres than female animals. In addition, in the male rats treated with PTU, gonadectomy decreased the B.W., pituitary content of GH-like protein and, concomitantly, the size of the goitre decreased; an opposite effect was induced by ovariectomy on the female animals. However, when goitrogenesis was induced in weight-paired adult rats of both sexes, the male animals still developed larger goitres than the females.

Among all the parameters studied here, the only ones which appeared to bear a consistent relationship with the size of the goitres in rats of different sexes, treated with a given goitrogen, were the rate of body growth and the amount of a pituitary GH-like protein found before the onset of the goitrogen treatment. Moreover, though the pituitary content of the GH-like protein decreased as a consequence of goitrogen treatment, it was still somewhat higher in male that in female animals.

The present results suggest that GH may somehow be involved in the mechanism by which male and female rats on goitrogens develop goitres of different sizes, despite equally high plasma TSH levels.