Comparison of in vivo long-term treatment of rats by methylene blue with its in vitro effects on thyroid hormone--nuclear receptor complex formation in liver

The present study was undertaken to investigate both in vitro effects of methylene blue and its long-term in vivo influence on 3,5,3'-L-triiodothyronine nuclear receptor binding characteristics in rat liver. In vitro, methylene blue at 1 nmol/l was found to inhibit (p < 0.05) the 3,5,3'-L-triiodothyronine (T3) specific binding to its cognate nuclear receptors. Methylene blue at 100 nmol/l significantly (p < 0.05) reduced the thyroid hormone receptor (TR) concentration (expressed as the TR maximal binding capacity). The equilibrium association constant (Ka) of that reduced number of TR resulting from 100 nmol/l methylene blue TR treatment was significantly higher (p < 0.05), when compared to samples without methylene blue. Moreover, the T3 was found to dissociate from the TR-T3 complex in the presence of 1 mumol/l methylene blue. In vivo long-term treatment of rats with 0.125%, 0.25% or 0.5% methylene blue for 28 days did not affect either the TR maximal binding capacity (Bmax) or the Ka values in comparison with rats fed a standard laboratory diet. The data based on both in vitro or in vivo experiments suggest that in spite of a direct and quick in vitro effect of methylene blue on liver TR concentration and/or TR-T3 dissociation, a long-term in vivo treatment of rats by three different methylene blue concentrations does not affect the thyroid hormone receptor status (the concentration and the affinity) in the liver.

[Endocrinology 1995-1996]

In a brief review of advances in endocrinology in the last two years the author discusses above all the vain expectations of a drug against obesity-the adipose tissue hormone leptin. Its elevated blood level in human obesity indicates that its secretion depends on the mass of adipose tissue and it is not certain whether leptin reduces the food intake in humans. Perhaps resistance to leptin is involved. New receptor diseases were revealed: mutation of LH receptors leads in both sexes to hypogonadism. Mutation of the calcium receptor in parathyroid cells leads to familial hypocalciuric hypercalcaemia or autosomal dominant hypocalcaemia. The complex regulation of the tonus of the vascular wall by endothelins is still the object of interest. Aquaporin is a renal protein which mediates the action of vasopressin. In the sphere of stress evidence is emerging on the participation of CRH in brain activity and the possibility to influence autoimmune inflammations and perhaps even AIDS by interference with the CRH-proopiomelanocortin-ACTH-cortisol system.

In vivo antiestrogenic activity of mifepristone in the rat

The aim of this study was to find out whether mifepristone, known mainly as a substance with an antiprogesterone and antiglucocorticoid effect, also has an in vivo antiestrogenic activity on the adenohypophysis of the rat. Male Wistar rats were given chronically either estradiol-benzoate (EB, 1 mg s.c. twice a week) for a period of 12 days, or the non steroidal antiestrogen tamoxifen (1 mg/day/rat), or mifepristone (1 mg/day/rat), or EB together with mifepristone or tamoxifen. The hypertrophic effect of the EB on the weight of the adenohypophysis (AP) was significantly suppressed both by tamoxifen and by mifepristone. Mifepristone and tamoxifen reduced the increased content of PRL in the estrogenized adenohypophysis. Mifepristone but not tamoxifen significantly increased the content of the LH in the adenohypophysis of estrogen treated rats. Mifepristone and tamoxifen suppressed the increased concentration of cyclic nucleotides cAMP and cGMP in the estrogenized adenohypophysis. Mifepristone given alone increased serum levels of corticosterone, but when given together with EB deepened inhibiting effect EB on them. The results of our preliminary study show that mifepristone exerts a weak antiestrogenic activity on the level of hypophysis, however the pharmacology is not identical to tamoxifen.

AgNORs in estrogen-induced and lisuride- and thyreoidin-inhibited rat anterior pituitary hyperplasia. Computer image analysis and nonautomated AgNOR typing

OBJECTIVE

A model of estrogen (E)-induced rat anterior pituitary hyperplasia blocked partly by thyroid hormones (estradiol plus thyreoidin [ET]) and nearly completely by lisuride (estradiol plus lisuride [EL]) and thyreoidin plus lisuride combination (estradiol plus thyreoidin plus lisuride [ETL]) was used to test a computer image analysis program, LUCIA, for argyrophilic nucleolar organizer region (AgNOR) evaluation.

STUDY DESIGN

Nuclear and AgNOR area were measured in more than 700 cells in each experimental group. The nucleoli were also typed without the automated procedure.

RESULTS

Mean nuclear area was significantly higher in E and lower in T. In all groups with blocked hyperplasia (ET, EL, ETL) the mean nuclear area was lower than in T. Mean AgNOR area was significantly higher in E but also, to a lesser extent, in T. The ET combination produced a partly diminished mean AgNOR area as compared to E; a severe reduction was observed in the EL and ETL groups. In nucleolar typing, thyreoidin, lisuride and their combination inhibited the increase in large nucleoli with finely dispersed AgNORs induced by estradiol.

CONCLUSION

The LUCIA image analysis program for AgNOR evaluation proved able to monitor the slight changes in AgNORs in thyroid hormones- and lisuride-inhibited, estradiol-induced rat anterior pitutary hyperplasia.

[Why is it necessary to study the thyroid gland?]

Pathophysiological and clinical aspects of the thyroid gland include after many decades of intensive studies many yet unresolved problems. The relationship with the gastrointestinal system (iodine accumulation in the stomach and salivary glands), the function of thyroxine as a prohormone (in particular the regulation of the activity of tissues deiodinases, the action of triiodothyronine similar to that of steroid hormones, a mixture of protein anabolic and protein catabolic reactions to thyroid hormones, peculiar immune features of the thyroid gland (presence of immunogenic hyperfunctional and hypofunctional syndrome), sharing of common antigens by the thyroid gland and orbital tissues, new findings on mutations of TSH receptors in the thyroid gland, biphasic dependence of the thyroid gland on iodine - all these problems call for further research. Mutation of the TSH receptor can lead to hypothyroidism (resistance to TSH) and to multinodular goitre. The gene for the iodine transporter in the thyroid gland (Na(+)I symport) was cloned. The thyroid gland is related to malignant free radicals: this is suggested also by the raised thyroxine level in rats after methylene blue administration. The increase is recorded in intact as well as carbimazole medicated animals. All this indicates that the thyroid gland must remain in the foreground of research and clinical work: 4% of the Czech population suffer from some thyroid disorder.

The endogenous digitalis-like factor

Intensive research into the presence of endogenous digitalis-like factor (EDLF) started shortly after identification of the alpha subunit of the Na,K,-ATPase as being receptor for digitalis glycosides. After years of skepticism, present data testify EDLF really exists. Most probably, the EDLF has chemical structure of either ouabain or of one of its isomers. It is secreted by the adrenal cortex, and, under conditions of stress, it's secretion is regulated differently from the secretion of both gluco- and mineralocorticoids. The physiological role of the EDLF has not been fully understood yet. In the newborn's kidneys, the inhibition of the Na,K-ATPase may assist to increase elimination of surplus sodium from the organism. In individuals of any age, the inhibitory influence of EDLF upon Na,K-ATPase in the arterial wall smooth muscle cells increases peripheral vascular resistance and thus, blood pressure. In the tissue culture, direct positive inotropic influences of EDLF upon rat cardiomyocytes was observed. However, the importance of positive inotropic effect of the EDLF upon the heart in clinical medicine remains to be elucidated.

Efficient retroviral infection of mammalian cells is blocked by inhibition of poly(ADP-ribose) polymerase activity

Integration of proviral DNA into the host cell genome is a characteristic feature of the retroviral life cycle. This process involves coordinate DNA strand break formation and rejoining reactions. The full details of the integration process are not yet fully understood. However, the endonuclease and DNA strand-joining activities of the virus-encoded integrase protein (IN) are thought to act in concert with other, as-yet-unidentified, endogenous nuclear components which are involved in the DNA repair process. The nuclear enzyme poly(ADP-ribose) polymerase (PARP), which is dependent on DNA strand breaks for its activity, is involved in the efficient repair of DNA strand breaks, and maintenance of genomic integrity, in nucleated eukaryotic cells. In the present work, we examine the possible involvement of PARP in the retroviral life cycle and demonstrate that inhibition of PARP activity, by any one of three independent mechanisms, blocks the infection of mammalian cells by recombinant retroviral vectors. This requirement for PARP activity appears to be restricted to processes involved in the integration of provirus into the host cell DNA. PARP inhibition does not affect viral entry into the host cell, reverse transcription of the viral RNA genome, postintegration synthesis of viral gene products, synthesis of the viral RNA genome, or the generation of infective virions. Therefore, efficient retroviral infection of mammalian cells is blocked by inhibition or PARP activity.

Triiodothyronine attenuates estradiol-induced increases in dopamine D-2 receptor number in rat anterior pituitary

Estrogens promote adenohypophyseal enlargement and tumor transformation, and thyroid hormones antagonize these effects. Hormone-induced pituitary enlargement may be mediated by alterations in pituitary dopaminergic function. The present study examined the effects of chronic (20 days) administration of estradiol benzoate (EB), triiodothyronine (T3), or EB and T3 (T3 + EB) on dopamine (D-2) receptors in rat anterior pituitary. D-2 receptor number increased after EB without altered receptor affinity. T3 alone did not affect D-2 receptor number in the anterior pituitary but significantly attenuated the effect of EB. T3 administration also inhibited EB-induced anterior pituitary hyperplasia. D-2 receptor upregulation by EB more likely could reflect a compensatory response to decreased receptor occupation. The present results suggest that D-2 receptors could play an important role in estrogen-induced adenohypophyseal tumor formation and hyperprolactinemia and that thyroid hormones may inhibit estrogen-induced pituitary tumor development via adenohypophyseal D-2 receptors.

[Methylene blue as an endocrine modulator: interactions with thyroid hormones]

Methylene blue (MB) is a thiazine dye used in the treatment of methemoglobinemia. Since it was shown to scavenge free radicals, it is now being examined clinically in reperfusion syndrome and septic shock. We tested methylene blue in a series of experimental endocrine situations, in which this scavenging effect could play a role. Indeed, we observed that MB partly inhibited the increase in adenohypophyseal weight and cAMP and prolactin levels after the administration of estrogens in male rats. MB also inhibited the increase of another scavenger of free radicals, the metalloenzyme ceruloplasmin in the blood of estrogenized rats. MB also inhibited the stimulation of bone mass after estradiol in male rats. In this respect, it behaved as an antiestrogen. In the bones, MB also prevented the increase of bone minerals induced by estradiol. MB also produced a decrease in adenohypophyseal ascorbic acid content an potentiated the effect of estradiol in the same direction. Surprisingly, blood thyroxine levels increased consistently in rats after MB treatment. An interaction of MB with thyroid hormone synthesis and/or actions thus should be evaluated. This idea is supported by our observation of an antagonistic action of MB in carbimazole-induced rise in thyroid weight and decrease in thyroxine blood levels. (Ref. 14.).

An increase in the blood thyroxine level after methylene blue in rats: the interaction with carbimazole

Anterior pituitary (AP) weight, thyroid weight, the serum thyroxine (T4) level, the thyroid T4 and cAMP content, the serum TSH level and the TSH and cAMP content of the AP and thyroid were measured in control rats, rats given methylene blue (MB) in their food, rats given the thyroid-blocking agent carbimazole (CARB) and rats fed both MB and CARB. AP weight fell slightly after MB in both intact and CARB--fed animals. Thyroid weight rose strongly after CARB, MB partly inhibited this increase. The cAMP content of the thyroid rose after CARB; this increase was likewise blocked by MB, MB alone had no effect on the thyroid cAMP concentration. Previous observations showing that MB produced an increase in the blood T, were confirmed. The T4 level fell, of course, after CARB and the decrease was partly inhibited by MB. The T4 content of the thyroid also fell after CARB, this decrease was completely reversed by MB. The blood TSH level fell slightly after MB and rose 7--fold after a CARB blockade of the thyroid; this increase was completely inhibited by MB. The TSH content of the AP fell after MB in both intact and CARB--fed animals. The cAMP content of the AP fell after MB, it was unaffected by CARB. Thus, in some way, MB raised the blood thyroxine level in both intact and CARB--fed animals and strongly depressed the TSH content in the serum and the AP given alone or with CARB. The mechanism of this action should be a result of MB interaction in thyroid hormone metabolism and their binding activity on specific regulatory elements. It is a problem for future experiments.

Lasp-1 (MLN 50) defines a new LIM protein subfamily characterized by the association of LIM and SH3 domains

MLN 50 was previously identified in a cDNA library of breast cancer metastasis. In this study, we show that MLN 50, which is expressed at a basal level in normal tissues, is overexpressed in 8% of human breast carcinomas most often together with c-erbB-2. MLN 50 cDNA encodes a putative protein of 261 residues, named Lasp-1 (LIM and SH3 protein) since it contains a LIM motif and a domain of Src homology region 3 (SH3) at the amino- and the C-terminal parts of the protein, respectively. Thus, Lasp-1 defines a new LIM protein subfamily.

[Endocrinology 1994-1995]

In a brief review of advances made in endocrinology during the past two years surprisingly the receptors for TSH and thyroid hormones occupy the foremost position. Mutations of the TSH receptor may cause congenital hyperthyroidism or resistance to TSH (mutation of the gene for TSH-receptor). An interaction of thyroid hormone receptor with a conserved transcriptional mediator was discovered. The reports on the treatment of neonatal respiratory distress syndrome with TRH are still controversial. CRH deficiency reveals neonatal but not adult glucocorticoid need--at least in mice. The concept of receptors was challenged by the discovery of "inverse agonists", i.e. ligand binding by (already) activated receptors. To make endocrinology even more complicated it was shown, that the congenital lipoid adrenal hyperplasia may be caused not by a deficiency in an adrenal cortex enzyme, but by a mutation of the mitochondrial transport protein (StAR), steroidogenic acute protein). The gene for X-linked congenital adrenal hypoplasia (DAX-1) was isolated, its mutation can cause a hypogonadotropic hypogonadism, too. Animals lacking functional estrogen receptor develop osteoporosis--this is true even in humans. Nitric oxide (NO) has more jobs in the body than previously thought-e.g. for maintenance of diurnal rhythms. The interest in endogenous cannabinoids is still flourishing, especially in the brain. Clinical implications of basic research are best documented by the discoveries of G-protein roles in clinical syndromes (e.g. pseudohypoparathyroidism, McCune-Albright syndrome, acromegaly and "testitoxicosis"). It should be emphasized that Nobel prize for medicine and physiology for the year 1994 was awarded to A. G. Gilman and M. Rodbell for the discovery of G-proteins.

A dominant-negative mutant of human poly(ADP-ribose) polymerase affects cell recovery, apoptosis, and sister chromatid exchange following DNA damage

Poly(ADP-ribose) polymerase [PARP; NAD+ ADP-ribosyltransferase; NAD+:poly(adenosine-diphosphate-D-ribosyl)-acceptor ADP-D-ribosyltransferase, EC 2.4.2.30] is a zinc-dependent eukaryotic DNA-binding protein that specifically recognizes DNA strand breaks produced by various genotoxic agents. To study the biological function of this enzyme, we have established stable HeLa cell lines that constitutively produce the 46-kDa DNA-binding domain of human PARP (PARP-DBD), leading to the trans-dominant inhibition of resident PARP activity. As a control, a cell line was constructed, producing a point-mutated version of the DBD, which has no affinity for DNA in vitro. Expression of the PARP-DBD had only a slight effect on undamaged cells but had drastic consequences for cells treated with genotoxic agents. Exposure of cell lines expressing the wild-type (wt) or the mutated PARP-DBD, with low doses of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) resulted in an increase in their doubling time, a G2 + M accumulation, and a marked reduction in cell survival. However, UVC irradiation had no preferential effect on the cell growth or viability of cell lines expressing the PARP-DBD. These PARP-DBD-expressing cells treated with MNNG presented the characteristic nucleosomal DNA ladder, one of the hallmarks of cell death by apoptosis. Moreover, these cells exhibited chromosomal instability as demonstrated by higher frequencies of both spontaneous and MNNG-induced sister chromatid exchanges. Surprisingly, the line producing the mutated DBD had the same behavior as those producing the wt DBD, indicating that the mechanism of action of the dominant-negative mutant involves more than its DNA-binding function. Altogether, these results strongly suggest that PARP is an element of the G2 checkpoint in mammalian cells.

Early and delayed effects of hydrocortisone and onapristone on intestinal brush-border enzymes and their sialylation and on thymus growth in suckling rats

The antigestagen-antiglucocorticoid onapristone (ZK 98.299) was tested on three glucocorticoid-sensitive systems after hydrocortisone (HC) administration to suckling male rats, by determining onapristone (ZK)-induced inhibition of HC-provoked (1) increase of activities of intestinal brush-border enzymes, (2) desialylation of brush-border components and (3) thymolysis. HC acetate (75 mg/kg body weight (b.w.)) was injected s.c. on postnatal days 9 and 10, and ZK (150 mg/kg b.w.) on days 9, 10 and 11. The animals were killed on day 12 for assessing the early effect, or on days 15-17 for determining the delayed effect of HC and ZK. In all three systems the glucocorticoid effects were antagonized by ZK. The most sensitive to HC were systems 1 and 3, which exhibited both the early and the delayed effects. The most sensitive to the counteraction of ZK against administered HC was system 1, where HC was antagonized in both its early and delayed effects, whereas only delayed antagonistic action against administered HC was found in system 2. ZK alone had an early inhibitory effect on the activities of several brush-border enzymes and produced an early increase in thymus weight, accompanied by an increased DNA-protein ratio. No delayed effects of ZK alone on the three systems were observed.

The effect of an anti-glucocorticoid (ZK 98299) on thymus evolution and on hydrocortisone-induced thymolysis, intestinal brush-border enzymes and their desialylation in suckling rats

1. The action in Onapristone infant male rats displays short-term and delayed effects. 2. Suppression of intestinal brush-border enzymes and increase of thymus mass were observed only immediately after 3-day treatment with Onapristone. After an additional 3 days its effect disappeared. There was no immediate or delayed effect of Onapristone on the desialylation of brush-border enzymes. 3. In the short-term and delayed effects, Onapristone suppressed the HC-provoked induction of several intestinal brush-border enzymes, especially alpha-glycosidases. In the delayed effect the drug also suppressed thymolysis induced by the exogeneously given glucocorticoid, and suppressed the HC-induced desialylation of a brush-border enzyme DP IV, which serves as a marker of the desialylation process. 4. These experiments seem to support a conclusion that the postnatal development of intestinal brush-border enzymes and the development of thymus in infant rats are controlled by endogeneously secreted glucocorticoids. 5. The control of sialylation of intestinal brush-border proteins by endogeneously secreted glucocorticoids during the postnatal development of the rat remains debatable.

Poly(ADP-ribose) polymerase: structure-function relationship

Dissection of the human poly(ADP-ribose) polymerase (PARP) molecule in terms of its structure-function relationship has proved to be an essential step towards understanding the biological role of poly(ADP-ribosylation) as a cellular response to DNA damage in eukaryotes. Current approaches aimed at elucidating the implication of this multifunctional enzyme in the maintenance of the genomic integrity will be presented.

A eukaryotic expression vector for the study of nuclear localization signals

We describe a new vector designed to produce beta-galactosidase fusion proteins which can be used to assess subcellular localization of target peptide fragments or proteins in eukaryotic cells. The vector was constructed in such a way as to produce the peptide of interest in fusion via a short linker of proline residues to the N terminus of the reporter protein. Efficiency of the transport machinery is optimized using this particular protein fusion construction. This vector has potential uses for readily testing putative nuclear localization sequences and identifying their crucial amino-acid residues.

Kin17, a mouse nuclear zinc finger protein that binds preferentially to curved DNA

Kin17 is a 45 kDa protein encoded by the KIN17 gene located on mouse chromosome 2, band A. The kin17 amino acid sequence predicts two domains, which were shown to be functional: (i) a bipartite nuclear localization signal (NLS) that can drive the protein to the cell nucleus, (ii) a bona fide zinc finger of the C2H2 type. The zinc finger is involved in kin17 binding to double-stranded DNA since a mutant deleted of the zinc finger, kin17 delta 1, showed reduced binding. Single-stranded DNA was bound poorly by kin17. Interestingly, we found that kin17 protein showed preferential binding to curved DNA from either pBR322 or synthetic oligonucleotides. Binding of kin17 to a non-curved DNA segment increased after we had inserted into it a short curved synthetic oligonucleotide. Kin17 delta 2, a mutant deleted of 110 amino acids at the C-terminal end, still exhibited preferential binding to curved DNA and so did kin17 delta 1, suggesting that a domain recognizing curved DNA is located in the protein core.

Methylene blue inhibits the stimulation of bone mass by high doses of estradiol in male rats

To elucidate the effect of methylene blue on bone metabolism we examined the rats treated with estradiol, with methylene blue alone and with estradiol and methylene blue. The mineral bone mass in the femurs of the animals was measured quantitatively. A significant increase of bone density and bone mineral content was found in the estradiol treated animals compared to animals without estradiol. The rise in bone mineral content after estradiol was inhibited by methylene blue. Methylene blue alone did not affect bone mineral mass. From our work the possibility arose that beside well known effect of estradiol on osteoblast receptors also other mechanism of estrogen action exists which possibly may include the effect of estrogen on cytosolic guanylate cyclase producing cGMP.

Structure and function of poly(ADP-ribose) polymerase

Poly(ADP-ribose) polymerase (PARP) participates in the intricate network of systems developed by the eukaryotic cell to cope with the numerous environmental and endogenous genetoxic agents. Cloning of the PARP gene has allowed the development of genetic and molecular approaches to elucidate the structure and the function of this abundant and highly conserved enzyme. This article summarizes our present knowledge in this field.

[Endocrinology 1992-1993]

In a brief review of advances made in endocrinology during the past two years, focused on steroid hormones, the author discusses findings on mineral corticoid and glucocorticoid receptors and their interaction with hormone responsive elements in nuclei of target cells. The antimicrobial action of some steroid hormones and general characteristics of the cell reaction to stress (proteins of heat shock) are also new findings. In the region of peptide hormones the author mentions findings pertaining to the mechanisms of development of adenohypophyseal adenomas, probably by the action of GHRH. It is assumed that some derivatives of prostaglandins will have an antiviral and anti-tumorous effect. An endogenous ligand for tetra-hydro-cannabinol receptors was isolated. Preventive administration of insulin protects relatives of patients with diabetes mellitus type I from the development of the disease.

[New findings on endogenous drug receptor ligands]

Since the discovery of endogenous ligands for opiate receptors, endorphins and enkephalins some 30 years have elapsed. The fact that one of the breakdown products of the common precursor (proopiomelanocortin, POMC) ACTH and opioid peptides, i.e. ACTH 1-24 has a saluretic effect (balancing perhaps sodium retention after activation of the adrenal cortex) was not generally accepted yet although MSH as well as some fragments of the ACTH molecule have a natriuretic effect. The endogenous digitalis-like immunoreactive factor, DLF (even ACTH displays some DLF activities) which inhibits NaK-ATPase originates from the adrenals and is probably identical with ouabain, although I have doubts on conclusive evidence. The physiological function of DLF is not known either. Endogenous benzodiazepines ("endozepins") probably play a part in the modulation of cerebral activity: their excess may be associated with a nosological entity, idiopathic recurrent stupor. Nitric oxide, a mediator of vasorelaxing reactions, caused by acetylcholine, has already penetrated into general clinical thinking. There are at least ten diseases where NO plays a part. It is not only an endogenous factor which imitates more perfectly the action of organic nitrates but also a nervous mediator and it shares this function with another gaseous mini-hormone, carbon monoxide (CO). Endogenous ligands of drug receptors comprise also endogenous substances which interreact with receptors for calcium inhibitors (inhibitors of calcium channels). Here are important clinical perspectives not only in cardiology. There are moreover endogenous ligands for receptors for marihuana (tetrahydrocannabinols) in particular a derivative of arachidonic acid anandamide (substance of "inner bliss").(ABSTRACT TRUNCATED AT 250 WORDS)

An analog of MIF, alaptide: effect on serum prolactin, dopamine receptors and growth of rat adenohypophysis

Alaptide is a drug chemically derived from prolyl-leucyl-glycin amide (PLG) which is effective after oral administration. We studied the effect of long term treatment with alaptide and estradiol-benzoate on serum prolactin, growth reactivity and dopamine DA-2 receptors in the anterior pituitary of male rats. Alaptide reduced adenohypophyseal weight when given alone, but only nonsignificantly reduced growth reactivity of the anterior pituitary (AP) raised by estradiol-benzoate (EB). Alaptide significantly decreased the serum level of prolactin but, on the other hand, significantly increased the binding of 3H-spiperone to dopamine DA-2 receptors in AP membrane preparations, without affecting affinity. The administration of alaptide plus EB together resulted in an additional increase of dopamine DA-2 binding sites. We assume that alaptide has a weak dopaminergic activity on the AP of male rats.

Long-term results of uncemented alumina acetabular implants

We report the clinical and tribological performance of 67 ceramic acetabular prostheses implanted between 1976 and 1979 without bone cement. They articulated with ceramic femoral heads mounted on mental femoral stems. After a mean elapsed period of 144 months, 59 sockets were radiographically stable but two showed early signs and six showed late signs of loosening. Four of the loose sockets have been revised. Histological analysis of the retrieved tissue showed a fibrous membrane around all the implants, with fibrocartilage in some. There was no bone ingrowth, and the fibrous membrane was up to 6 mm thick and infiltrated with lymphocytes, plasma cells, and macrophages. Intra- and extracellular birefringent wear particles were seen. Tribological analysis showed total wear rates in two retrieved alumina-on-alumina joints of 2.6 microns per year in a stable implant and 68 microns in a loose implant. Survival analysis showed a revision rate of 12.4% at 136 months.