Baseline serum TSH levels predict the absence of thyroid dysfunction in cancer patients treated with immunotherapy

PURPOSE

Immunotherapy against immune checkpoints has significantly improved survival both in metastatic and adjuvant setting in several types of cancers. Thyroid dysfunction is the most common endocrine adverse event reported. Patients who are at risk of developing thyroid dysfunction remain to be defined. We aimed to identify predictive factors for the development of thyroid dysfunction during immunotherapy.

METHODS

This is a retrospective study including a total of 68 patients who were treated with immune checkpoint inhibitors (ICIs) for metastatic or unresectable advanced cancers. The majority of patients were treated with anti-PD1 drugs in monotherapy or in combination with anti-CTLA4 inhibitors. Thyroid function and anti-thyroid antibodies, before starting immunotherapy and during treatment, were evaluated. Thyroid ultrasound was also performed in a subgroup of patients at the time of enrolment in the study.

RESULTS

Eleven out of 68 patients (16.1%) developed immune-related overt thyroid dysfunction. By ROC curve analysis, we found that a serum TSH cut-off of 1.72 mUI/l, at baseline, had a good diagnostic accuracy in identifying patients without overt thyroid dysfunction (NPV = 100%, p = 0.0029). At multivariate analysis, both TSH and positive anti-thyroid antibodies (ATAbs) levels, before ICIs treatment, were independently associated with the development of overt thyroid dysfunction during immunotherapy (p = 0.0001 and p = 0.009, respectively).

CONCLUSIONS

Pre-treatment serum TSH and ATAbs levels may help to identify patients at high risk for primary thyroid dysfunction. Our study suggests guidance for an appropriate timely screening and for a tailored management of thyroid dysfunctions in patients treated with ICIs.

Should familial disease be considered as a negative prognostic factor in micropapillary thyroid carcinoma?

PURPOSE

An increased aggressiveness of familial papillary thyroid carcinoma (FPTC) compared with sporadic form has been reported. On the contrary, the biological behavior of familial microPTC (FmPTC) is still debated. To assess if familial diseases should be considered as a negative prognostic factor in mPTC, the clinical presentation and outcome of FmPTC and sporadic mPTC (SmPTC) were compared.

METHODS

We retrospectively analyzed 291 mPTC (SmPTC n = 248, FmPTC n = 43) patients followed for a median follow-up of 8.3 years. FmPTC was defined as the presence of PTC in two or more first-degree relatives, after excluding hereditary syndromes associated with PTC.

RESULTS

FmPTC patients had more frequently bilateral tumor (32.6% versus 16.5%, p = 0.01) and lymph node metastases at diagnosis (30.2% versus 14.9%, p = 0.02). At the first follow-up, FmPTC patients had a higher rate of structural disease and a lower rate of remission compared to SmPTC (p = 0.01). Also in a multivariate model, using a "CHAID tree-building algorithm", familial disease correlated with a worse clinical presentation and outcome of mPTC patients. Familial disease was associated with a higher rate of intermediate risk patients in non incidental mPTC and with a higher rate of structural incomplete response in mPTC without lymph node metastases (p = 0.01).

CONCLUSIONS

Like in macroPTC, the familial form of the diseases has been shown to be a negative prognostic factor also in mPTC, therefore, it should be highly regarded in the management of mPTC patients.

Autoimmune thyroid diseases are more common in patients with prolactinomas: a retrospective case-control study in an Italian cohort

BACKGROUND

Prolactin may exert immunological effects. Over the years, a higher prevalence of autoimmune thyroid diseases (ATD) has been reported in patients with prolactinomas (PRLs) in areas with sufficient iodine intake.

PURPOSE

The aim of our study was to evaluate the prevalence of ATD [Graves' disease (GD) and chronic autoimmune thyroiditis (AIT)] in a retrospective cohort of Italian patients with PRLs compared to a sex-matched control group, represented by subjects with non-functioning pituitary adenoma (NFPA) or empty sella (ES).

MATERIALS AND METHODS

We enrolled 149 patients (108 F/41 M) with PRLs (110 micro/39 macro) and 143 subjects (100 F/43 M) with NFPA (n = 96, 56 micro/40 macro) or ES (n = 47), with normal serum prolactin. Neck ultrasound and thyroid function tests (anti-thyroid antibodies, TSH, FT3 and FT4) were performed in all patients.

RESULTS

In PRLs, median serum prolactin was significantly higher (98.3 vs. 8.9 ng/ml, p ≤ 0.0001), while age was lower (34 vs. 46 years, p ≤ 0.001) compared to controls. The prevalence of ATD was 13.4% (20/149) in PRLs (1 GD and 19 AIT) compared to 6.3% (9/143) in the controls (p = 0.042). At the multivariate analysis, serum prolactin was the only independent factor predicting ATD. Thyroid volume (12.5 ± 5.9 ml vs. 12.8 ± 10 ml, p = 0.47) and the presence of uni- or multinodular goiter (29.5% vs. 35%, p = 0.35) did not differ between PRLs and control groups.

CONCLUSIONS

Our data in an area with mild iodine deficiency confirm a higher prevalence of ATD in patients with prolactinomas.

A novel monoclonal antibody-based enzyme-linked immunosorbent assay to determine luteinizing hormone in bovine plasma

The development of a novel enzyme-linked immunosorbent assay (ELISA) for determining luteinizing hormone (LH) in bovine plasma is described. Anti-bovine LH (bLH) monoclonal antibodies (mAbs) were produced and characterized. One mAb recognizing the bLH β subunit was used for immunoaffinity purification of substantial amounts of biologically active bLH from pituitary glands. The purified bLH in combination with 2 anti-bLH β subunit mAbs was used to develop a sandwich ELISA, which satisfied all the criteria required to investigate LH secretory patterns in the bovine species. The ELISA standard curve was linear over the range 0.05 to 2.5 ng/mL, and the assay proved suitable for measuring bLH in plasma without any prior treatment of samples. Cross-reactivity and recovery tests confirmed the specificity of the method. The intra- and inter-assay coefficients of variation ranged between 3.41% and 9.40%, and 9.29% and 15.84%, respectively. The analytical specificity of the method was validated in vivo by provocative tests for LH in heifers, using the LH releasing peptide gonadotropin-releasing hormone. In conclusion, the adoption of mAbs for this ELISA for coating the wells and labeling, combined with the easy one-step production of reference bLH, ensures long-term continuity in large-scale measurements of LH in the bovine species.

A collaboration of aquaporins handles water transport in relation to the estrous cycle in the bitch uterus

Fluid movement through uterine cell membranes is crucial, as it can modulate the tissue imbibition pattern in the different phases of the estrous cycle. To gain insight into the mechanisms underlying steroid-controlled water handling, the presence and distribution of aquaporins (AQPs), integral membrane channel proteins permitting rapid passive water movement, was explored in bitch uterine tissues. Immunohistochemistry and Western immunoblot analysis were used to study the presence of AQP1, AQP2, and AQP5 in the layers of the bitch uterine wall during the different estrous phases. Presence of endothelial nitric oxide-generating enzyme NO synthase (NOS3) was also investigated, as it is known that the vasodilator NOS3 might be involved in the development of uterine edema. The results demonstrated the following: (1) AQP1, AQP2, and AQP5 were present in the uterus of cycling bitches. (2) AQP1 was localized within uterine mesometrial, myometrial, and endometrial blood vessels and in the circular and longitudinal layers of myometrium. AQP1 localization and expression were unaffected by the estrous cycle. (3) The estrogenic milieu was probably at the basis of AQP2 expression in the glandular and luminal epithelium of the endometrium. (4) AQP5 water channels were present in the apical plasma membrane of uterine epithelial cells in coincidence with plasma progesterone increase. (5) NOS3 was localized in the myometrial and epithelial tissues as well as in blood vessels indicating a contribution of this vasoactive peptide to the uterine imbibition processes. Thus, we can hypothesize that a functional and distinctive collaboration exists among diverse AQPs in water handling during the different functional uterine phases.

Oxacilin-resistant Coagulase-negative staphylococci (CoNS) bacteremia in a general hospital at São Paulo city, Brasil

In the last decades, coagulase-negative staphylococci (CoNS), especially Staphylococcus epidermidis have become an important cause of bloodstream infections. In addition, rates of methicillin-resistance among CoNS have increased substantially, leading to the use of glicopeptides for therapy. The objective of this study was to evaluate eleven consecutives clinically relevant cases of oxacillin-resistant CoNS bacteremia in a general hospital localized in São Paulo city, Brazil. Five different species were identified by different phenotypic methods, including S. epidermidis (5), S. haemolyticus (3), S. hominis (1), S. warneri (1) and S. cohnii subsp urealyticus (1). A variety of Pulsed Field Gel Electrophoresis profiles was observed by macrorestriction DNA analysis in S. epidermidis isolates, but two of three S. haemolyticus isolates presented the same profile. These data indicated the heterogeneity of the CoNS isolates, suggesting that horizontal dissemination of these microorganisms in the investigated hospital was not frequent. One S. epidermidis and one S. haemolyticus isolates were resistant to teicoplanin and susceptible to vancomycin. The selective pressure due to the use of teicoplanin in this hospital is relevant.

Relationship between growth hormone concentrations in bovine oocytes and follicular fluid and oocyte developmental competence

In the last few years, several works suggest that Growth Hormone (GH) is involved in follicular development and oocyte maturation. These actions may reflect endocrine roles of pituitary GH and also account for local autocrine or paracrine activities of GH produced in reproductive tissue. This study was aimed to verify whether the developmental competence of bovine female gametes might be related to ovarian GH. We evaluated the localisation and distribution of GH in the cumulus oocytes complexes (COCs) and the concentration of GH in the oocytes and in the follicular fluids (FF) from ovaries classified on the basis of the follicles number. Oocytes retrieved from ovaries with more than 10 follicles of 2 to 5 mm in diameter (High ovaries, Hi) show higher rate of maturation and blastocyst formation than those retrieved from ovaries with less than 10 follicles (Low ovaries, Lo). At the same time we measured Estrogen (E2) and Progesterone (P4) concentrations in FF, to relate oocytes quality, GH concentration and follicle health. GH localization in COCs and oocytes was performed by indirect immunofluorescence and its concentration within the ooplasm was evaluated by microspectrophotometer analysis. GH, E2 and P4 concentrations in FF were measured by an Enzyme Linked ImmunoSorbent assay (ELISA). We observed a positive, diffuse signal at cytoplasmic level in most of the cumulus cells, with no differences between COCs collected from Hi and Lo ovaries. On the contrary, GH level was significantly higher in the oocytes collected from Lo ovaries than in those recovered from Hi ovaries. Finally we found that also GH level in the FF was inversely related to the oocytes developmental capability. We suggest that the increase of GH in the oocytes and in the FF derived from Lo ovaries might be interpreted as attempt of the follicular environment to improve ovarian activity and in turn oocytes developmental competence in a autocrine-paracrine manner. Moreover, E2, and P4 levels in FF suggest that, in our model, atresia processes are also involved in oocyte developmental capability and that the highest level of GH may represent a local reaction to these phenomena.

Heterophile antibody interference in a solid phase sandwich immunoassay for detection of equine growth hormone in plasma

Heterophile antibodies (HAs) present in serum recognize animal immunoglobulins and are one of the most unpredictable causes of false results in immunoassays. However, no study has yet reported their interference on the diagnostic reliability of immunochemical analyses on horse plasma. Recently, we developed a sandwich ELISA for detection of equine growth hormone (eGH) in plasma. In a pilot study to measure basal eGH levels (blood samples were drawn from 13 horses every 10 min for 1h), we noted one horse with abnormally high eGH (>100 ng/mL). We demonstrate here that this plasma eGH level was falsely elevated due to interference from HAs. The interfering antibodies were polyspecific immunoglobulins, with fairly broad species-specificity, which affected the eGH immunoassay by bridging the mouse IgG capture antibody and the rabbit IgG conjugate. This produced artificial sandwiches which led to overestimation of the eGH plasma concentration. Spiking horse plasma with pure mouse and rabbit immunoglobulins or whole plasma of several species significantly reduced but did not totally eliminate the HAs interference. Immunoglobulins and whole plasma differed in their ability to block the interference, suggesting that HAs may recognize other proteins beside immunoglobulins in animal sera. To investigate whether HAs have any implications in equine clinical practice, we decided to seek information on the incidence of HAs interference in normal animals. We collected single plasma samples from another 114 horses and we found that 5 of these had plasma HAs. Therefore, in total 6 out of the 127 horses examined (4.7%) had plasma HAs generating falsely elevated eGH measures. In conclusion, this study provides the first evidence of HAs in horse plasma interfering with an immunoassay and indicates that veterinary surgeons and diagnostic laboratory staff should be aware of this potential for interference in tests on horse plasma using monoclonal or polyclonal antibody reagents.

Effects of disease progression and L-dopa therapy on the control of reaching-grasping in Parkinson's disease

The present study aimed to determine whether the bradykinesia of Parkinson's disease (PD) patients during the execution of reaching-grasping movements (i) is related to an impaired implementation of movement parameters and (ii) selectively involves the control of reach and/or grasp movements. We compared the kinematics of reaching to grasp of differently sized objects placed at different positions, among PD patients in the early stage of disease (ESPD), in the advanced stage of disease (ASPD) without L-dopa medication (off-state), and in healthy controls. In addition, we analysed the effects of L-dopa replacement therapy by comparing the kinematics of the patients in the advanced stage of disease after L-dopa administration with those of the other groups. Bradykinesia increased with disease progression, but only in the initial phases of the reach and grasp components. However at both stages of the disease, the kinematics of reaching and grasping responded to extrinsic and intrinsic object properties just as in controls. L-dopa administration improved the performance of PD patients, though this was more evident for the reach than for the grasp. We suggest that the basal ganglia (BG) are involved in implementing kinematic parameters, but neither (or only marginally) in the initial movement parameterization itself, nor in the on-line control of movement. Specifically, the BG dysfunction in PD induces a slowed implementation of movement parameters. The lack of effect of L-dopa administration on grasp kinematics may be because the motor control of distal effectors is less represented in the motor circuitry formed by the supplementary motor area (SMA), thalamus and BG.

Identification of commercial fish species belonging to the orders pleuronectiformes and gadiformes: library of isoelectric focusing patterns

Isoelectric focusing in polyacrylamide gel was used to establish an identification archive of fish species belonging to the orders Pleuronectiformes, or flat fish, and Gadiformes, or gadoid fish. The 2 orders include species of different commercial value and interest that are frequently requested in European fish markets, but are susceptible to substitution either because they are morphologically similar or because they arrive on the markets already filleted or sliced. The sarcoplasmic protein profiles are species-specific and reproducible. The use of densitometry and image analysis coupled with a simple computer program overcomes the subjective evaluation of the patterns, making it possible to identify species correctly.

Amino acid modifications in canine, equine and porcine pituitary growth hormones, identified by peptide-mass mapping

Modified amino acid residues in porcine, canine and equine growth hormones purified from pituitary glands were characterised by tryptic mapping and high-performance liquid chromatography with on-line coupled electrospray ionisation mass spectrometry (HPLC-ESI-MS) detection. Hormones from all three species showed the same changes. Conversion of Asp128 to iso-Asp128 was a component of native hormones, while deamidation of Asn12 and Asn98 to Asp and iso-Asp, oxidation of Met4, and cyclisation to the pyroglutamyl derivative of Gln139, probably occurred in vitro, during isolation, storage or hydrolysis. Porcine and canine hormones had indistinguishable protein fingerprints, confirming the assumption, based on their cDNA sequences, that their mature primary structures are identical.

Effects of complexation with in vivo enhancing monoclonal antibodies on activity of growth hormone in two responsive cell culture systems

We describe the properties of three monoclonal antibodies (MAbs) to ovine GH, two of which have previously been shown to enhance, in vivo, the biological activity of bovine and ovine growth hormone. We have examined the effects of these MAbs on GH activity in two appropriate GH-responsive cell culture systems, investigating both acute signalling effects (Janus-activated kinase (Jak)-2 tyrosine phosphorylation -5 min) and longer-term (MTT-formazan production -24 h) effects of hormone-antibody complexes. In the 3T3-F442A pre-adipocyte cell line (which has been demonstrated to be GH responsive), we show that complexation of recombinant bovine (rb) GH with either of the two enhancing anti-ovine GH MAbs (OA11 and OA15) and the non-enhancing MAb, OA14, attenuates the ability of GH to stimulate tyrosine phosphorylation of Jak-2 at a 5-min time point. Using the mouse myeloid cell line, FDC-P1, stably transfected with the full-length ovine GH receptor (oGHR), we demonstrate that rbGH causes a dose-dependent increase in MTT-formazan production by these cells. Further, we demonstrate that OA11 and OA14, but not OA15, cause a decrease in this stimulatory activity of rbGH over a hormone concentration range of 5-50 ng/ml at both 24 and 48 h. We conclude that the different in vitro activities of the two in vivo enhancing MAbs are most probably related to the time-courses over which these two assays are performed, and also to the relative affinities between antibody, hormone and receptor. In addition, the in vitro inhibitory activity of the enhancing MAb OA11 in both short- and long-term bioassay lends further support to an exclusively in vivo model for MAb-mediated enhancement of GH action.

Binding and signalling properties of a growth hormone enhancing monoclonal antibody

We have used a sequential, qualitative biosensor based assay to demonstrate that OA15, a monoclonal antibody which enhances in vivo the activity of bovine growth hormone (bGH) does not disrupt the interaction between bGH and its cognate receptor (as represented by recombinant bovine GH binding protein -rbGHBP). We have confirmed this using a classical cell-based radio-receptor assay with the GH-responsive mouse pre-adipocyte cell line 3T3-F442A. The fact that OA 15 binding to bGH still allows hormone to interact with its receptor, allows us to test the hypothesis that there is any amplification of signalling events following hormone-MAb treatment of 3T3-F442A cells. We have used as a reporter of GH activity the rapid stimulation of JAK-2 tyrosine phosphorylation which is a critical first step in GH signalling events. We demonstrate that binding of rbGH by OA15 attenuates hormone stimulation of JAK-2 tyrosine phosphorylation. We conclude that although OA15 does not disrupt GH-GH receptor (GHR) interactions it does interfere with subsequent GH activity at the molecular and cellular level. We further speculate therefore that the biological enhancing activity of this antibody is most likely due to an in vivo effect as presentation of antibody-hormone complexes to a GH-target cell inhibits hormone activity.

Plasma levels of GH and PRL and concentrations in the fluids of bovine ovarian cysts and follicles

Prolactin and GH have been detected within the ovary, and it has become increasingly evident that they have a role as intrafollicular regulatory factors. The aim of the present work was to gain an insight into the elements influencing intraovarian GH and PRL in bovine species and to see whether cystic degeneration was accompanied by abnormal bovine GH (bGH) and PRL (bPRL) plasma patterns. We followed the relationships between plasma and ovarian fluid bGH and bPRL concentrations over an entire year in Friesian cows whose ovaries showed distinct types of structures. To assess the presence of bGH and bPRL within ovarian cells, we assayed selected ovarian structures by immunohistochemistry. The results demonstrated that: 1) plasma and ovarian fluid hormonal concentrations were independent, and their ratio was independent of the ovarian structure classes, subclasses and period of the year; 2) in the majority of the cows the concentration of bGH in ovarian fluid was no more than 80% of the level in plasma, whereas in about half the animals bPRL concentrations were higher in the ovary than in peripheral plasma; 3) mean bPRL concentrations in ovarian fluids were significantly higher in summer than in winter; 4) immunoreactive bGH and bPRL were present within granulosa and luteal cells. Thus, it is suggested that in the cow bGH and bPRL levels in the ovary might be regulated in some way independently of the pituitary.

Structure and function of bovine growth hormone. Bovine growth hormone as an experimental model for studies of protein-protein interactions

Growth hormone (GH) is a polipeptide that controls the differentiation, growth and metabolism of many cell types, and is secreted from the hypophysis of all vertebrate species tested so far. Despite the overlapping evolutionary, structural, immunological and biological properties, it is well-known that GHs from distinct mammalian species have significant species-specific characteristics. The main purpose of this review is to highlight bovine GH (bGH) structural features related to its species-specific properties. Novel interest in bGH is also aroused by the advent of biotechnological methods for production of recombinant proteins. In fact recombinant bGH will have a great importance in veterinary medicine research and as a 'high tech' drug that needs to be monitored in zootechnical productions.

Growth hormone stimulates the secretion of insulin-like growth factor binding protein-2 (IGFBP-2) by monolayer cultures of sheep costal growth plate chondrocytes

Using monolayer cultures of costal chondrocytes established from four week old Clun Forest lambs, we have demonstrated that, under serum free conditions the cells release three IGFBPs (32, 29 and 21 kDa) into the medium. The most abundant of these--the 32 kDa BP--was shown to be IGFBP-2 by Western blotting. Furthermore we demonstrate that the levels of IGFBP-2 in conditioned medium are acutely increased (6, 12 and 24 h time points) following treatment of cells with bovine GH (1-100 ng/ml). In a parallel set of experiments, using ovine fibroblasts (derived from dermis) we show that IGFBPs of Mr 32, 29 and 21 kDa are also secreted by this cell type. However the relative abundance of these BPs differed from that seen in the chondrocyte cultures, with the 21 kDa species now the most abundant. In addition, prolonged exposure of autoradiographs indicated that fibroblasts secreted a higher Mr IGFBP (most probably ovine BP-3) that was not detected in any of our chondrocyte cultures. Most significant however was the demonstration that bGH did not dramatically affect the levels of IGFBPs in fibroblast cell cultures. We conclude that GH stimulates BP-2 production from chondrocytes and this is a cell-type specific effect in as much as it is not replicated in cultures of dermal fibroblasts.

Growth hormone but not prolactin concentrations in the fluid of bovine ovarian cysts are related to the cystic stage of luteinization

Regulation of follicular growth and ovulation as well as steroid production by the ovary depends principally on gonadotropins. However nonsteroid systemic hormones and autocrine and paracrine factors contribute to the regulation of ovarian function. The objectives of the present work were 1) to asses the presence of growth hormone (GH) and prolactin (PRL) in fluid drawn from normal bovine ovarian follicles, cysts or cystic corpora lutea; 2) to relate the stage of luteinization of the cyst with the GH and PRL concentrations in fluids; and 3) to asses the feasibility of providing a defined nonsteroid hormone marker to distinguish between normal and pathological ovarian structures. Cysts were classified according to histological and morphological appearance as follicular or luteal. Concentrations of GH, PRL, estrogens (E2), progesterone (P4) and testosterone (T) were measured in follicular and cystic fluids. On the basis of the E2 to P4 ratio, ovarian formation classes were further divided into two subclasses (E2 dominant and P4 dominant). The results provide evidence of 1) the presence of immunoreactive GH and PRL in all the follicular and cystic fluids assayed, 2) an increasing concentration of GH correlated to the stage of luteinization of the cyst and a direct correlation between GH and P4 concentrations, 3) a significant variability of intraovarian fluid PRL concentration not related to the histological class of the cyst nor to the concentrations of steroid hormones examined, and 4) the possibility of distinguishing 6 different ovarian formation classes by merely measuring GH, P4, E2 and T concentrations in fluids. These data contribute to a better understanding of the endocrine milieu of bovine ovarian cystic degeneration.

Monoclonal antibodies against recombinant human growth hormone as probes to study immune function

Monoclonal antibodies were raised against human recombinant growth hormone (rhGH) and those that did not cross-react with other human recombinant proteins like prolactin (PRL), interleukin 2 (IL-2), insulin, or bovine pituitary growth hormone were selected. The selected hybridoma supernatants were studied for their ability to influence T lymphocyte proliferation when induced either by a mitogen, such as phytohemagglutinin (PHA), or by alloantigen. All supernatants inhibited proliferation. Three MAbs were then purified by several passages on antimouse IgG (or IgM)-agarose columns, and characterized. These MAbs recognized three different epitopes, as revealed by competition study, although their inhibitory effect on PHA-induced T cell proliferation was quite similar. The data demonstrate that the MAbs were not cytolytic, that they did not interfere with the PHA binding to T cell membranes, and, as revealed by FACS analysis, did not bind to the membrane. Finally, these MAbs immunoprecipitated a 44-kDa molecule from PHA-activated T cell-concentrated supernatants. These data indicate that the MAbs recognized a soluble factor that plays a central role in T cell proliferation and that is probably the immune growth hormone.

Inverse control of growth hormone and prolactin secretion in clonidine-stimulated dairy cattle

Clonidine is a specific alpha-2-adrenoreceptor agonist that stimulates growth hormone (GH) release in animals and humans. This drug was used to study the GH and prolactin (PRL) secretory response in dairy cows and heifers. An i.v. infusion of 10 micrograms/kg body weight induced GH release to a peak concentration after 30-60 min, while 2 micrograms/kg had no effect on GH secretory patterns. Plasma PRL decreased significantly (P < 0.01) starting 15-60 min after both doses of clonidine, this effect lasting up to 6 h. Clonidine significantly lowered plasma insulin (P < 0.01) and raised plasma glucose (P < 0.01). The changes in plasma GH, PRL, insulin and glucose differed significantly between doses, the 10 micrograms/kg dose being more effective (P < 0.01). The results of our investigation in dairy cattle provide evidence of (i) an increase in GH release after 10 micrograms/kg clonidine; (ii) a concomitant decrease in PRL secretion, hence GH and PRL secretion in cattle appear inversely controlled; (iii) a significant difference between the effects of the 2 and 10 micrograms/kg doses and (iv) no relationship between the changes in plasma GH and PRL after clonidine and plasma hormone levels before treatment.

Matrix-assisted laser desorption mass spectrometry for the detection of recombinant bovine growth hormone in sustained-release form

We employed matrix-assisted laser desorption mass spectrometry (LD-MS) to detect recombinant bovine growth hormone (r-bGH) in sustained-release preparations. After preliminary extraction in phosphate buffer, LD-MS provided a precise determination of the molecular mass (M(r)) of the r-bGH contained in 38 sustained-release preparations. The hormone was characterised using enzyme immunoassay, immunoblotting and amino acid sequencing. Rapid detection is essential for analysing large numbers of samples, and for monitoring the use of r-bGH in zootechnical productions and its administration as a "high-tech" drug for therapeutic purposes.

Monoclonal antibodies can reveal immunoreactivity differences between pituitary and recombinant bovine growth hormone

Monoclonal antibodies (MAbs) to pituitary bovine growth hormone (bGH) were used to assay the immunoreactivity of a recombinant form of bGH. The recombinant hormone used differed from the pituitary principally in the presence of a short amino acid sequence starting with methionine added to the N-terminal end of the molecule. Monoclonal antibody 1D2 recognized the recombinant hormone with greater affinity than the pituitary hormone, whereas MAb 5G1 bound the recombinant molecule with a lower strength than the pituitary. The other MAbs showed different behavior depending on the type of immunoassay used. Results indicate that the recombinant bGH molecule has been altered in its immunological structure, and suggest a possible interaction of the added N-terminal fragment with the three-dimensional structure of the hormone.

Circadian and circannual plasma secretory patterns of growth hormone and prolactin in Fresian heifers: hormonal profiles and signal analysis

The circadian and circannual secretory patterns of growth hormone (GH) and prolactin (PRL) in Fresian heifers were analysed to identify the significant pulses, the shape and the periodic components of the pulsatile signal that may be relevant to intercellular communication. The possible influence of temperature and photoperiod over these hormonal secretions has also been investigated. In the bovine GH (bGH) secretory patterns the basal levels and number, magnitude and amplitude of significant secretory peaks seem to be independent and not affected by seasonal changes. All the bGH circadian patterns show two periodic components with distinct frequencies. The bovine PRL (bPRL) circadian secretion shows basal levels, number and magnitude of the secretory peaks greater in summer than in winter; the periodic components are only one in winter, but two in summer. There is a significant increase of plasma bPRL in the May-July period and a correlation of the circannual hormone profile with both temperature and daylength.

An immuno-dominant sequential epitope recognized by mouse anti-recombinant bovine growth hormone antisera

The sequential epitopes on bovine growth hormone (bGH) recognised by five polyclonal mouse antisera have been identified by scanning with multiple pin-bound peptides. Four main epitopes were identified at residues 29-40, 101-110, 139-152 and 181-191. Of these, only epitope 139-152 is recognised by all five mouse antisera indicating that, for the mouse, this may represent an immuno-dominant region of the bGH molecule.

Chemical modification of functional arginyl residues in beef kidney D-aspartate oxidase

Chemical modification of beef kidney D-aspartate oxidase by phenylglyoxal is a biphasic process involving the transient formation of an enzymatic species with a decreased activity versus dicarboxylic substrates, an increased activity versus D-proline and a new activity versus other monocarboxylic D-amino acids which is absent in the native protein. Prolonged incubation with the modifier causes complete inactivation of the enzyme. The presence of the competitive inhibitor L-tartrate in the incubation mixture prevents enzyme inactivation. Kinetic and structural data suggest that complete loss of activity is paralleled by modification of eight arginine residues, of which two are critical for the specificity and the activity of the enzyme. We propose that the two essential arginine residues are located in the substrate binding site of D-aspartate oxidase.

Binding characteristics of monoclonal antibodies raised against bovine growth hormone

Monoclonal antibodies have been raised against pituitary bovine growth hormone using the hybridoma procedure. The binding characteristics of the seven selected monoclonal antibodies toward the antigen molecule in its native, chemically or enzymatically treated form have been studied. The reactivities of the monoclonal antibodies with growth hormones from other species and bovine prolactin have also been investigated. The epitopes recognized by four of the produced monoclonal antibodies are conformational, whereas two other monoclonal antibodies bind to sequential determinants. Three antibodies define immunological sites located between residues 6-124 of the bovine growth hormone molecule, and one of this antibody shows higher affinity to human than bovine growth hormone. The immunoreactivity of one monoclonal antibody is enhanced by the previous binding of the antigen to polyclonal antibodies, probably because of a localized conformational change of the bovine growth hormone molecule. This antibody also shows cross-reactivity with all the homologous hormones tested, indicating to recognize a highly conserved antigenic determinant.

Purification to homogeneity of bovine prolactin by high-performance ion-exchange chromatography

Homogeneous bovine prolactin (bPRL) has been obtained using a procedure based on high-performance anion-exchange chromatography. The procedure enables up to 6 mg of 99.4% pure bPRL to be obtained per hour, with a recovery of 32.4%. The purity of the protein was checked by N-terminal sequencing and sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The highly purified bPRL obtained with this method is suitable for complete structural and immunochemical studies.

High-performance liquid chromatographic determination of D-amino acid oxidase activity

A new procedure for the assay of D-amino acid oxidase activity has been developed. alpha-Ketoisovaleric acid, derived from D-valine, was estimated by high-performance liquid chromatography after reaction with o-phenylenediamine to give the corresponding quinoxalinol derivative. alpha-Ketovaleric acid was used as an internal standard to ensure the reproducibility of the method. As an example of application, kidney cortex homogenates were analyzed for their D-amino acid oxidase activity. The advantages of the presented procedure for the determination of the enzymatic activity in biological samples compared with previously reported procedures are discussed.

An enzyme-linked immunosorbent assay for the determination of bovine prolactin in plasma

Highly purified pituitary bovine prolactin (bPRL) has been used in a sensitive non-competitive enzyme-linked immunosorbent assay of prolactin (PRL) concentrations in plasma. In this assay affinity purified polyclonal antibodies were immobilized to the solid phase in order to capture the antigen, and were also used biotinylated as the detector antibody. The method was found to be reproducible (3% variability between calibration curves) and has been optimized for measuring bPRL concentration in plasma samples, giving an intra-assay coefficient of variation of about 5% and an interassay coefficient of variation of about 9%. The sensitivity of the assay was found to be as low as 0.1 ng/ml of bPRL.

A biotin-avidin sandwich enzyme-linked immunosorbent assay of growth hormone in bovine plasma

Purified pituitary bovine growth hormone (bGH) has been used to develop a homologous sandwich enzyme-linked immunosorbent assay in which affinity-purified antibodies are immobilized on microtiter plates. Bovine GH bound to specific antibody is then revealed with a second anti-bGH antibody labeled with biotin and peroxidase-conjugated avidin. The method requires only 48 h, including the coating step, and has a sensitivity as low as 0.25 ng/ml of bGH. Statistical analyses (test of parallelism, cross-reactivity among bGH and GH of various species and bovine prolactin, recovery test, within- and between-assay variation, comparison with radioimmunoassay) confirm the high specificity and reproducibility of the method.

Detection of desamido forms of purified bovine growth hormone

Tryptic peptide mapping and amino acid sequencing were used for the identification of desamido forms of bovine growth hormone. The major desamido forms of bovine growth hormone resulted from deamidation of asparagine in position 13, 148 and glutamine 140. These forms did not seem to be produced by prolonged treatment of bovine growth hormone in tryptic hydrolysis.

Studies on analogues of succinic semialdehyde as substrates for succinate semialdehyde dehydrogenase from rat brain

The methyl ester of succinic semialdehyde (SSA) was examined as a substrate for succinate semialdehyde dehydrogenase (SSADH) from rat brain. It was found that the ester can be oxidized by the enzyme. Values of Km for SSA-Me were higher than for those for SSA, and for this substrate the enzyme showed a substrate-dependent inhibition. This finding suggests that the carboxylate group of SSA is not essential in the process of inhibition of SSADH by the substrate. Cyclopropyl analogues of SSA, cis- and trans-1-formyl-cyclopropan-2-carboxylic acids, were also individually tested as substrates of SSADH. Only the trans isomer was found to be oxidized to the corresponding dicarboxylic acid; it inhibited the enzyme in the same range of concentrations as SSA. The above data suggest that, as for gamma-aminobutyric acid, SSA is present in an unfolded, transoid conformation at the active site of SSADH.

C5a fragment of bovine complement. Purification, bioassays, amino-acid sequence and other structural studies

C5a and des-Arg-C5a have been purified from bovine serum in milligram amounts. The progress of the purification was followed by measuring the chemotactic activity of the complement fragments. The two polypeptides induce activation of neutrophil-oriented locomotion and secretion with very similar dose/response effects. After preparing a rabbit antiserum to bovine C5a/des-Arg-C5a, a competitive enzyme-linked immunosorbent assay (ELISA) was set up for the detection of C5a from 5 ng/mol to 1 microgram/ml. The complete primary structure of bovine C5a, which consists of 74 amino acids, has been determined by sequence analysis of the tryptic peptides, aligned by peptides derived from a chymotryptic digest, and by partially sequencing the intact molecule. Bovine C5a has a sequence homology of 78% and 70% with porcine and human C5a, respectively, reacts with an antiserum to porcine C5a and is recognized by cell surface receptors on human neutrophils. Finally, the secondary structure of bovine C5a was investigated by circular dicroic spectroscopy and predicted from the amino acid sequence. A comparison of the content and distribution of alpha-helical and/or hydropathic regions, suggests that the three-dimensional structure of C5a might be modeled from the known crystal structure of the homologous C3a molecule.

Immunopathology of the eye: purification of canine retinal "S" antigen

Canine retinal S antigen has been purified to study the retinal progressive atrophy of the dog. The purified antigen will be used to detect, by the ELISA technique, specific autoantibody in dogs with ocular diseases.