Corneal toxicity of xylazine and clonidine, in combination with ketamine, in the rat.

PURPOSE: To compare the corneal toxicity of xylazine (XYL)/ketamine (KET) with that of clonidine (CLO)/KET in the rat, in the presence or not of the alpha(2)-adrenergic antagonist yohimbine (YOH). METHODS: XYL (10 mg/kg) and CLO (0.15 mg/kg) were administered subcutaneously in the rat in combination with KET (50 mg/kg), in the presence or not of YOH (2 mg/kg). RESULTS: The corneas immediately lost transparency and luster, but recovered within 120 min. By both light and electron microscopy, a marked stromal edema and alterations of all layers were observed. In addition, XYL/KET altered the permeability of the cornea as indicated by the augmented levels of (14)C-indomethacin, topically administered 30 min after the anesthetic combination. CONCLUSIONS: The mechanism of the corneal toxicity of XYL and CLO in the rat is unclear but we speculate that: (a) proptosis and inhibition of normal blinking did not play a major role because topical application of hyaluronic acid did not protect against it; corneal decompensation, edema and opacification could be due to (b) osmotic or (c) mechanical endothelial stress: the first resulting from the sudden increase of the glucose concentration in the aqueous humor due to the well-known inhibition of insulin release by alpha(2)-adrenergic agonists, and the second from the acute elevation of intraocular pressure caused by these alpha(2)-adrenergic mydriatics in the rat; (d) addition, XYL and CLO could act by directly interacting with local alpha(2)- or, possibly, alpha(1)-adrenergic receptors, whose function is still not clear but probably essential for corneal homeostasis.

Two new male contraceptives exert their effects by depleting germ cells prematurely from the testis.

The three currently available male contraceptive approaches are 1) the barrier method such as the condom, 2) hormonal methods by disrupting the pituitary-testicular axis so as to impair spermatogenesis, and 3) immunological methods by preparing vaccines against male-specific antigens. We hereby describe an alternative approach in which attachments of developing germ cells onto the seminiferous epithelium are disrupted, thereby inducing their premature release into the tubular lumen. This in turn leads to infertility. A panel of analogues based on the core structure of 1-(2,4-dichlorobenzyl)-indazole-3-carboxylic acid was synthesized. These compounds were subjected to an in vivo screening assay assessing their effects in inducing the expression of testin, a testicular marker whose expression correlates with the integrity of Sertoli-germ cell junctions. An induction of testin expression in the testis signifies a disruption of Sertoli-germ cell junctions that is followed by depletion of germ cells from the seminiferous epithelium. Two compounds, namely 1-(2,4-dichlorobenzyl)-indazole-3-carbohydrazide (AF-2364) and 1-(2,4-dichlorobenzyl)-indazole-3-acrylic acid (AF-2785), were identified that caused detachment of germ cells, in particular round and elongated spermatids, from the epithelium inducing their premature release into the tubular lumen as confirmed by histological analysis. Adult rats receiving several oral doses of either one of these compounds became infertile within 3-7 wk after the epididymal sperm reserve was exhausted. Depending on the dosing of the administered compound, rats became infertile for 4-14 wk before their fertility gradually bounced back, illustrating the reversibility and efficacy of these new compounds. Also, these compounds did not appear to impair the hypothalamus-pituitary-testicular axis because the serum levels of LH, FSH, and testosterone of the treated animals did not change significantly when compared to control rats. In addition, results of serum microchemistry illustrate that liver and kidney function was not affected in animals treated with both compounds.

Inhibition of heat-induced denaturation of albumin by nonsteroidal antiinflammatory drugs (NSAIDs): pharmacological implications.

The activity of nonsteroidal antiinflammatory drugs (NSAIDs) in rheumatoid arthritis is not only due to the inhibition of the production of prostaglandins, which can even have beneficial immunosuppressive effects in chronic inflammatory processes. Since we speculated that these drugs could also act by protecting endogenous proteins against denaturation, we evaluated their effect on heat-induced denaturation human serum albumin (HSA) in comparison with several fatty acids which are known to be potent stabilizers of this protein. By the Mizushimas assay and a recently developed HPLC assay, we observed that NSAIDs were slightly less active [EC50 to approximately 10(-5)-10(-4) M] than FA and that the HPLC method was less sensitive but more selective than the turbidimetric assay, i.e. it was capable of distinguishing true antiaggregant agents like FA and NSAIDs from substances capable of inhibiting the precipitation of denatured protein aggregates. In conclusion, this survey could be useful for the development of more effective agents in protein condensation diseases like rheumatic disorders, cataract and Alzheimers disease.

Analysis of lonidamine in rat serum and testis by high performance liquid chromatography.

A HPLC method for the determination of lonidamine in serum and testis, suitable for pharmacological studies in the rat and other mammals, has been developed. Briefly, 0.5 mL of serum or about 0.2 g of testicular tissue were extracted with ethyl acetate and evaporated to dryness under nitrogen. The residue was redissolved in methanol and an aliquot was injected onto a C18 column eluted with a mobile phase consisting of acetonitrile:water (51:49, v/v), containing 0.1% trifluoroacetic acid. The eluate was monitored at 230 nm with a sensitivity of 0.05 AUFS. By this method, the pharmacokinetics and the serum and testicular levels of the drug up to 120 h after the administration of one single dose (100 mg/kg body weight) of lonidamine to Sprague-Dawley rats have been studied. Results were highly variable, as previously reported, but a very good linear correlation was found between the serum and the testicular levels, suggesting that, in the rat, and possibly in the human, testicular levels could be estimated based on the serum concentrations.

Changes of lipocalin type prostaglandin D-synthase in the seminal plasma of subfertile man.

It was proposed that lipocalin type prostaglandin D synthase (L-PGD-S), a bifunctional protein both synthesizing PGD2 and transporting retinoids and other lipophilic ligands, could be involved in the development and the maturation of sperm. In the present study, the seminal plasma (SP) of 59 adult males was analyzed by standard WHO methods and immunoblotting, using a monospecific polyclonal antibody directed against L-PGD-S. Briefly, aliquots of SP (2.5 microl), were fractionated by polyacrylamide electrophoresis in the presence of sodium dodecyl sulfate, the blots were stained and densitometrically analyzed. To obtain quantitative data, the aliquot of SP was selected within the linear part of the dose/band intensity curve and a proper quality control was analyzed in all blots to normalize the intensity of the bands of different experiments. A significant reduction (p<0.05) of the L-PGD-S levels was observed in severe oligozoospermic patients compared to normozoospermic subjects and a significant correlation between L-PGD-S levels and sperm concentration was found, as reported by other authors. Further studies are warranted to evaluate the possible diagnostic and pharmacological applications of these observations.

Relaxant effects of Hydrastis canadensis L. and its major alkaloids on guinea pig isolated trachea.

Hydrastis or goldenseal, one of the most popular medicinal herbs in the U.S.A., is used in mild pathological conditions like cold and flu, based on the pharmacological properties of its active components, berberine (anticholinergic, antisecretory, and antimicrobial) and beta-hydrastine (astringent). We previously reported the relaxant effect of a total ethanolic extract of hydrastis on carbachol precontracted isolated guinea pig trachea, and with the present study, using the same experimental model, we aimed at evaluating the contribution of its major alkaloids, berberine, beta-hydrastine, canadine and canadaline to the total effect. Furthermore, using specific pharmacological tools, like timolol and xanthine amine congener, we attempted to elucidate its mechanism of action. The EC50 of berberine, beta-hydrastine, canadine and canadaline, were 34.2+/-0.6, 72.8+/-0.6, 11.9+/-1.2 and 2.4+/-0.8 microg/ml, respectively. Timolol effectively antagonized the effect of canadine (EC50 = 19.7+/-3.0 microg/ml) and canadaline (EC50 = 17.1+/-1.2 microg/ml) but not that of berberine and beta-hydrastine, while xanthine amine congener antagonized the effect of beta-hydrastine (EC50 = 149.9+/-35.3 microg/ml) and canadaline (EC50 = 26.1+/-3.0 microg/ml) but not that of berberine and canadine. Besides, the hydrastis extract, at concentrations between 0.01 and 0.1 microg/ml, potentiated the relaxant effect of isoprenaline on carbachol-precontracted isolated guinea pig trachea. These data, which are insufficient to draw definite mechanistic conclusions, indicate that the aforementioned alkaloids may act by interacting with adrenergic and adenosinic receptors.

Changes of acute-phase proteins in streptozotocin-induced diabetic rats.

Quantitative and qualitative changes of serum proteins, apart from glycation, have not been sufficiently studied in streptozotocin-induced diabetic rats (D), the most common experimental model for diabetes. Thus, we decided to analyze the serum of diabetic rats by concanavalin A-blotting in comparison with rats with acute inflammation induced by fermented yeast (Y), in which characteristic alterations of serum proteins have been described. Two months after the streptozotocin treatment, the blood glucose levels were highly elevated (456+/-24 vs. 124+/-10 mg/dl, p<0.001, n=12), the body weight was significantly lower than normal (279+/-10 vs. 392+/-6 g, p<0.001, n=12), and serum proteins appeared to be highly glycated (p<0.001) when analyzed by the fructosamine assay, without any significant change in the total serum protein concentration. Analysis by concanavalin A-blotting, revealed a significant decrease of alpha1-inhibitor-3 (alpha1-I3, p<0.05) and an increase of the beta chain of haptoglobin (beta-Hp, p<0.05) in both D and Y rats (n=3) compared with control animals. However, acute inflammation caused a marked rise of two prominent acute phase proteins, alpha2-macroglobulin and hemopexin, which did not change appreciably in diabetic rats. Further work will be necessary to evaluate the physiopathological significance of these phenomena which could result from changes of both concentration and glycosylation of the aforementioned proteins.

Effects of lonidamine on testicular and epididymal proteins in the rat.

The mechanism responsible for the antispermatogenic activity of lonidamine (LND) [1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid], a drug with low systemic toxicity and lack of significant hormonal effects, is still unclear but may be related to alterations of Sertoli cell proteins. Here, we confirmed that a single oral dose of LND (100 mg/kg b.w.) to sexually mature Sprague-Dawley rats causes shrinkage and weight reduction of the testes after 48 h. These macroscopic changes correlated with histologic alterations revealed by light microscopy, consistent with partially reversible inhibition of spermatogenesis. When the testes and the epididymides of animals treated with or without LND were homogenized and analyzed by the Bradford assay, a significant increase of total protein content was observed after 24 and 48 h. When these homogenates were analyzed by concanavalin blotting, specific changes of the major rat macroglobulins, i.e. alpha(1)-inhibitor-3, alpha(2)-macroglobulin, and alpha(1)-macroglobulin, were noted. In particular, LND caused a decrease of testicular alpha(1)-inhibitor-3, but not an increase of testicular alpha(2)-macroglobulin, indicating a mild local inflammatory response to the drug.

Aflatoxins inhibit prolactin secretion by rat pituitary cells in culture.

Acute effects of aflatoxins (AF), and in particular hormonal actions, have not been examined as much as chronic toxicity. Thus, we studied the effects of specific AF on prolactin (PRL) secretion by rat pituitary cells in culture. AFB1 and AFQ1 (1 x 10(-4) M) reduced the stimulating effect of dimethyl sulfoxide on PRL secretion by cultured rat pituitary cells. The mechanism responsible for this action is still unknown, but it did not seem to be a non specific toxic effect, because AFB1, at the same concentration, did not significantly alter cell viability, as indicated by the Trypan blue dye-exclusion test.

Stimulation of guinea pig isolated atria by aflatoxins.

Acute effects of aflatoxins (AF), and in particular cardiac actions, have not been examined as much as chronic toxicity. Thus, in the present study we evaluated the effects of specific AF on isolated guinea pig atria. Isoprenaline (ISO, 4x10(-9)), AFB(1) (3x10(-6) and 6x10(-5) M) and AFG(1) (3x10(-6) and 6x10(-6) M) contracted the isolated guinea pig atria, leaving the preparation hyperresponsive to ISO. These properties of AF are of interest as they could be responsible of certain cardiotoxic effects described in the literature.

Relaxant effects of aflatoxins on isolated guinea pig trachea.

Dyspnea is one of the symptoms of acute aflatoxicosis. Contrary to expectations, we observed that naturally occurring aflatoxins (AF) AFB(1), AFB(2), AFG(1), and AFG(2) and their major metabolites AFM(1), AFM(2), AFP(1), AFQ(1), and AFG(2a) relaxed carbachol (C) precontracted guinea pig trachea to different degrees. The efficacies but not the potencies of AFB(1), AFB(2), AFG(1), and AFG(2) were similar to that of the beta-agonist, isoprenaline, whose activity was potentiated by the AF. Their mechanism of action is not clearly understood but several mechanistic indications were obtained with AFB(1): 1) its effect was not influenced by the beta-blocker, timolol, indicating that a direct interaction with beta(2)-adrenergic receptors was not involved. 2) AFB(1) potentiated PGE(1) and PGE(2), two relaxant prostaglandins, and its activity was reduced by indomethacin. 3) The cAMP level in the guinea pig trachea relaxed by AFB(1) increased, possibly due to inhibition of phosphodiesterase; direct interaction with PG receptors; and/or interaction with A(2) adenosinic receptors, suggested by the inhibitory activity of XAC, a specific antagonist. 4) Finally, since tetrodotoxin reduced the relaxant activity of AFB(1), it is speculated that this mycotoxin could stimulate inhibitory nonadrenergic, noncholinergic nerves (i-NANC). In conclusion, the symptoms of acute aflatoxicosis do not seem to be due to a direct activity on the tracheal muscle, but rather, to the well-known pro-inflammatory activity of the aflatoxins, which are capable of releasing arachidonic acid from cell membranes.

Simultaneous determination of hydrocortisone, dexamethasone, indomethacin, phenylbutazone and oxyphenbutazone in equine serum by high-performance liquid chromatography.

Ethyl acetate extracts of equine serum, containing 0-5 microg/ml of hydrocortisone (HYD), dexamethasone (DEX), oxyphenbutazone (OPB), indomethacin (IND), phenylbutazone (PB) and probenecid as internal standard, were evaporated with nitrogen, resuspended in methanol and analyzed by HPLC, using a C-18 column equilibrated with 51:49 acetonitrile-water, 0.1% trifluoroacetic acid, at 1 ml/min. The eluate was monitored at 254 nm. The selectivity (inter-assay C.V.<4%), sensitivity (limits of quantitation of 0.25 microg/ml for HYD, DEX and IND, 0.5 microg/ml for PB and 1 microg/ml for OPB, despite the occurrence of significant degradation of OPB and PB during the analysis) and precision (intra-assay and inter-assay C.V.'s of about 3-6 and 9-15%, respectively) of the method appeared appropriate for anti-doping control of racehorses.

Inhibition of heat-induced aggregation of beta- and gamma-crystallin by alpha-crystallin evaluated by gel permeation HPLC.

The capability of alpha-crystallin (alpha-C), a known molecular chaperon, of protecting beta-C and gamma-C against heat-induced aggregation was studied by gel permeation high performance liquid chromatography. The activity was calculated using a formula based on the changes in the areas under the chromatographic peaks of these proteins, which appeared well separated. When heat-induced aggregation was studied in the range 22-90 degrees C, beta-C appeared more stable than gamma-C. The activity of alpha-C in stabilizing gamma-C but not beta-C was already relevant at 60 degrees C, but the maximum activity was higher (about 35%) for beta-C than for gamma-C. This method could be useful for studying the effect of drugs with potential anti-cataract activity on heat-induced aggregation of individual lens proteins.

Micropurification of beta- and gamma-crystallins from rabbit aqueous humor.

Soluble crystallins are normally present in the aqueous humor, originating from the lens, and their concentration may increase in certain conditions such as cataract, possibly contributing to aqueous outflow pathway obstruction, leading to glaucoma. Whether the stability and the tendency of aqueous crystallins to aggregate are different in patients with certain forms of open-angle glaucoma has not so far been established, mainly due to the lack of a suitable purification procedure from this fluid in which crystallins are present at very low concentration together with dozens of other proteins. About 4 microg each of beta- and gamma-crystallins were obtained from 20 ml of rabbit aqueous humor by C8 reversed-phase high-performance liquid chromatography (HPLC) and high-performance electrophoresis chromatography (HPEC). The identity of the proteins was confirmed by amino acid analysis following sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and electrophoretic blotting onto polyvinylidene fluoride membranes, with or without previous digestion with Staphylococcus aureus protease V8.

Micromethods for the analysis of tear proteins in pharmacological studies.

Although it is well established that ocular mucins and other proteins are essential for tear film stability, whether certain drugs, like non steroidal antiinflammatory drugs (NSAIDs), could cause ocular dryness by inhibiting their secretion is not known. To perform these and other studies of pharmacological interest, we evaluated several micromethods for the analysis of tear samples. The major proteins of the tear fluid collected in capillaries, i.e. IgA, lactoferrin, tear specific prealbumin and lysozyme, were analyzed by SDS-PAGE and gel permeation HPLC, using 2.5-5 microliters of sample. Gastric mucin (PGM), examined as a standard, was analyzed by solid phase assays based on previously described histochemical staining methods: dot blot assays were performed using small disks of polyvinylidene difluoride or nylon membranes, prepared by an ordinary paper punch, which were coated with PGM and stained by Alcian blue or the periodic acid Schiff's reagent. The densitometric analysis was carried out using an ordinary flat scanner controlled by a personal computer equipped with an inexpensive software. The sensitivity of these simple assays was low (100-500 micrograms) but considered sufficient for certain studies. A more sensitive assay (5-20 micrograms) was developed by immobilizing PGM in small agarose gels (100 microliters), prepared in the wells of 96-well microplates, which could by stained by stains-all and analyzed by an automatic plate reader at 595 nm.

Development of an enzyme-linked immunosorbent assay, using a monoclonal antibody against alpha2-macroglobulin, for the diagnosis of systemic lupus erythematosus.

OBJECTIVES: To develop an enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody (mab) directed against abnormally glycosylated serum alpha2-macroglobulin (alpha2-M) from patients with systemic lupus erythematosus (SLE). DESIGN AND METHODS: Serum alpha2-M purified by HPLC from patients with SLE was injected in a Balb/c, CB6 F1 female mouse and hybrid cell lines were screened using alpha2-M Glu-C fragments derived from SLE and normal donors (NHS). A mab was selected and used to develop an ELISA by which sera from NHS (n = 14), SLE (n = 34), rheumatoid arthritis (n = 15), Sjögren's syndrome (n = 11), mixed connective tissue diseases (n = 12), and liver diseases (n = 11) were analyzed. RESULTS: The affinity of the mab for alpha2-M from SLE, but not from the other diseases, was higher compared to NHS, as demonstrated by immunoblotting and ELISA. CONCLUSIONS: The ELISA was capable of recognizing changes of glycosylation of alpha2-M in SLE and may be useful for its differential diagnosis.

Changes in concanavalin A-reactive proteins in neurological disorders.

Changes of glycosylation of cerebrospinal fluid proteins such as alpha2-macroglobulin, and prostaglandin D synthase were studied by lectin blotting, using concanavalinA, in multiple sclerosis (n = 42) and neuropathies (n = 20) in comparison to neurological controls (n = 22). The concanavalinA-reactivity of alpha2-macroglobulin, which was increased in the neuropathies but not in multiple sclerosis compared to controls, correlated with the total concanavalinA-reactivity in controls and neuropathies but not in multiple sclerosis, indicating that the protein could be abnormally glycosylated in the latter disease. Although the concentration and the concanavalinA-reactivity of prostaglandin D synthase were not significantly different in the three groups, the two parameters correlated only in neuropathies but not in controls or multiple sclerosis, probably due to the high heterogeneity of the protein. These changes deserve to be studied in further detail in view of their potential clinical applications.

Differential changes in alpha2-macroglobulin and hemopexin in brain and liver in response to acute inflammation.

Changes in serum and cerebrospinal fluid (CSF) proteins following generalized acute inflammation induced by fermented yeast in the rat was examined by concanavalin A-blotting, immunoblotting, and radioimmunoassay. Using alpha2-macroglobulin (alpha2-M) and hemopexin (HPX) as marker proteins, the concentration alpha2-M was found to increase in serum and CSF by 150- and 5-fold, respectively, whereas the concentration of HPX increased by about 4-fold in both fluids following yeast-induced inflammation. The lesser increase in alpha2-M in the CSF versus the systemic circulation is not likely to be the result of changes in the permeability of the blood--brain barrier, since no change in the total protein content of CSF was detected in inflamed rats when compared to control animals. These results, however, illustrate the regulation of the same protein, such as alpha2-M, in two separate organs within the same animal can be drastically different. These results also suggest a possible protective role of alpha2-M in the brain during acute inflammation. Moreover, these observations are consistent with the previous observation that there is a differential response in the level of alpha2-M between the testis and the systemic circulation during inflammation.

Interaction of hyaluronic acid with mucin, evaluated by gel permeation chromatography.

Hyaluronic acid (HA) is known to increase the ocular bioavailability of ophthalmic drugs not only for its viscous properties but also for its specific affinity for ocular mucins. This phenomenon, called bio- or mucoadhesion, can be evaluated in vitro by mechanical tests which, however, require considerable amounts of mucin (M) that are difficult to obtain from ocular surfaces. Thus, we developed an alternative method, based on gel permeation liquid chromatography, to examine the interaction of HA with microgram quantities of mucin. HA (from human umbilical cord or rooster comb) were fractionated using a Sepharose CL-4B column, before and after incubation with porcine gastric mucin (PGM), and the fractions were analyzed by a specific assay based on the histological dye Stains-all. PGM interacted with high molecular weight (M.W). HA, causing the displacement of low M.W., non-covalently bound, HA fragments, which were eluted under a distinct chromatographic peak. By quantitating the relative area of this peak, an evaluation of the mucoadhesion of HA could be obtained. This method could be useful to study the interaction between HA and microgram quantities of ocular M (mucin), obtained from individual patients or normal subjects.

Quantification of prostaglandin D synthetase in cerebrospinal fluid: a potential marker for brain tumor.

Prostaglandin D synthetase (PGD-S; prostaglandin-H2 D-isomerase, EC 5,3,99,2), a 30 kDa glycoprotein also known as beta-trace protein that catalyzes the formation of prostaglandin D2 (PGD2) from PGH2, was purified to apparent homogeneity from human cerebrospinal fluid (CSF) using a two-step procedure involving HPLC on a Vydac C8 reversed-phase column and high performance electrophoresis chromatography (HPEC) using a 10% T SDS-polyacrylamide gel. The purity of PGD-S isolated from CSF was confirmed by silver stained SDS-polyacrylamide gel and direct protein microsequencing (NH2-APEAQVSVQPNFQ). A highly specific polyclonal antibody was prepared against this protein for immunoassay development. Using an ELISA, it was found that the concentration of PGD-S in CSF did not alter significantly in different pathological conditions of the central nervous system (CNS). These include dementia (n = 9), hydrocephalus (n = 4), neuropathy (n = 11), optic neuritis (n = 4), multiple sclerosis (n = 11), and demyelinating syndrome (n = 11), when compared to normal individuals (n = 12); however, the level of PGD-S in the CSF obtained from patients with brain tumor (n = 11), was reduced by as much as 2-fold when compared to control samples (n = 12) illustrating PGD-S is a potentially useful marker for brain tumor.