An enzyme-linked antiglobulin test for assessing anti-D immunoglobulin preparations

Two enzyme-linked antiglobulin tests (ELAT) for assessing anti-D IgG preparations are described; one is performed in tubes and the other in microtitre plates. An anti-human IgG alkaline phosphatase conjugate and the substrate p-nitrophenyl phosphate are used. Both methods were sensitive and reproducible, with variations coefficients of 7.8 and 8.6% for enzyme immunoassay in tubes and microplates, respectively. The linear relationship between the amount of red cell-bound anti-D and the optical density shows that the method is suitable for quantitative studies. Results obtained by the two methods show a very good correlation (r = 0.99) in 12 of the 14 samples assayed, and both give good agreement with results obtained in automated haemagglutination. Since microtitre plate ELAT has numerous advantages over the tube method, it could provide an alternative method for assessing anti-D activity of specific IgG preparations in control laboratories.

[Oat cell carcinoma of the esophagus]

Extrapulmonary locations of undifferentiated small cell carcinoma of the "oat cell" type are uncommon. In spite of its rarity, the appearance of this type of tumor has been described in various organs of the economy. Of these, the esophagus is the most common location, constituting 0.05 to 7.6% of esophageal carcinomas. Of uncertain histopathologic origin, these tumors are characterized by their extreme aggressiveness, which carries a poor short term prognosis. Surgery, radiotherapy and chemotherapy, separately or in combination, have produced discouraging results in the treatment of primitive esophageal "oat cell" carcinoma. In this paper are presented four cases of esophageal "oat cell" carcinoma treated in the Hospital de la Santa Cruz y San Pablo in 1979-1988, out of a total of 260 carcinomas in the same location. The clinical evolution and pathological findings of this type of tumor are commented. The literature on this unusual histological type of carcinoma is reviewed.

[IgG anti HSV I antibodies in saliva in a drug dependent population]

It is known the presence of receptors for the morphine products on the Lymphocytes B. These receptors could have a modulator action on the production of antibodies in drug addicts. We have determined the existence of IgG anti-HSV I in saliva and serum in a heroin population. Our results show that here is not significant differences between the heroin population and the control group, when the antibodies are detected in serum. But significant differences do exist between the number of people with antibodies anti-HSV I in saliva.

Surgical outlook regarding leiomyoma of the rectum. Report of three cases

The authors report experience with three patients with leiomyomas of the rectum between the years 1979 and 1987. Since Malassez's first description in 1872, approximately 200 cases have been reported. The diagnosis of these rare tumors is difficult. The authors present the ultrasonic characteristics of rectal leiomyoma by means of endorectal ultrasound, a method which, although not definitive, does delimit and orient the diagnosis in regard to the rectal mass and the follow-up of these tumors. A histologic diagnosis constitutes a dilemma between benign and malignant forms. The authors believe that treatment should always be surgical, realizing local extirpation when the histologic study reveals no signs of malignancy; even though it is mandatory to perform regular follow-up checkups (mainly with endorectal ultrasound) and radical treatment in regard to malignant lesions and local relapse of the anterior forms.

Fertilization in vitro of human oocytes by spermatozoa collected in different stressful situations

It has been shown that semen quality is impaired in couples undergoing in-vitro fertilization (IVF), probably due to stress. A possible effect of stress on the ability of spermatozoa to fertilize human oocytes in vitro was analysed in the present study composed of 26 couples with normozoospermic men undergoing IVF. A semen sample was obtained during the infertility work-up and was cryopreserved (sample 1). A second sample (sample 2) was provided after oocyte retrieval during the IVF cycle. Sample 1 was thawed and both samples were washed and preincubated for oocyte insemination. One-hundred-and-five oocytes were inseminated using thawed sample 1, and 120 with sample 2. Semen parameters such as density, progressive motility and percentage of abnormal forms were compared between sample 1, before and after freezing, and sample 2. Only motility was significantly (P less than 0.01) decreased by cryopreservation in sample 1, but no parameter was significantly different when fresh sample 1 was compared to sample 2. The fertilization rate was 78.6% using sample 1 in comparison to 87.5% when sample 2 was employed (not significant, NS). Cleavage rates were 77.7 and 89.7%, respectively (NS). A group of five patients undergoing IVF who needed donor semen served as a control for the effect of sperm cryopreservation on IVF. In these cases, the donor was asked to provide a fresh sample. Half of this sample was frozen and thawed. Subsequently, fresh and thawed samples were prepared for insemination and oocytes inseminated either with the fresh preparation (n = 24) or the frozen and thawed spermatozoa (n = 22).(ABSTRACT TRUNCATED AT 250 WORDS)

Is the retrieval of high numbers of oocytes desirable in patients treated with gonadotrophin-releasing hormone analogues (GnRHa) and gonadotrophins?

Continuous administration of gonadotrophin-releasing hormone analogues (GnRHa) in patients stimulated for the purpose of IVF might have a direct effect on the ovary. We have evaluated the IVF outcome of patients treated with Buserelin and subsequently with a combination of follicle-stimulating hormone (FSH) and human menopausal gonadotrophin (HMG). Patients were divided into three groups according to the number of oocytes obtained by transvaginal ultrasound-guided follicular aspiration: group 1 (n = 35), in which 1-5 oocytes were retrieved; group 2 (n = 30), in whom 6-10 oocytes were obtained; group 3 (n = 32), in whom greater than or equal to 11 oocytes were collected. Only couples with normal semen samples at oocyte retrieval were included in this study. The dose of Buserelin employed was not different between groups. However, the amount of FSH/HMG necessary to reach an optimal response significantly (P less than 0.01) decreased as follicular development increased. The quality of the oocytes obtained was evaluated based on the appearance of the oocyte-corona-cumulus complex, fertilization rate, morphological appearance of the embryos, and implantation rate. The fertilization rate was significantly (P less than 0.01) decreased in group 3 (57.2%) in comparison with groups 1 (77.1%) and 2 (74.2%). There was no significant difference between the groups in the quality of the embryos obtained or the quality of those replaced into the uterus. The implantation rate per embryo transferred was significantly (P less than 0.05) higher in group 1 (16.5%) in comparison with groups 2 (6.6%) and 3 (8.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

[Cordopexy. Surgical technic and results. 4 years' experience]

We show our experience during four years, with a new technique used in the management of bilateral vocal cord paralysis. We expose clearly the surgical technique, and the obtained results. We have done 15 cordopexy techniques to 10 patients with bilateral vocal cord paralysis, from different etiology, being the thyroid gland surgery, the most frequent.

Detection of bovine herpesvirus type 1 via an immunoperoxidase method, using monoclonal antibodies

The sensitivity and specificity of the immunoperoxidase technique, using monoclonal antibodies, for the detection of bovine herpesvirus type 1 (BHV-1) was assessed and compared with viral isolation methods. In this study, BHV-1 antigens were detected in impression smears of brain obtained from calves in which BHV-1 was isolated. False-positive results were not observed after double-blind examination. Preliminary identification of isolates as antigenic variants was possible by use of 3 monoclonal antibodies reactive with neurotropic and/or pneumotropic strains of BHV-1. Results were consistent with previous work in which characterization was performed by use of immunofluorescense and ELISA. The immunoperoxidase technique, using monoclonal antibodies, was determined to be specific and sensitive, compared with viral isolation, for the diagnosis of BHV-1 encephalitis. In addition, it has operative advantages in that the assay does not require tissue culture facilities, and results can be obtained within hours after specimens are obtained.

Ovarian response and outcome of in-vitro fertilization in patients treated with gonadotrophin-releasing hormone analogues in different phases of the menstrual cycle

Gonadotrophin-releasing hormone analogues (GnRH-a) are currently used in combination with gonadotrophins in ovarian stimulation for in-vitro fertilization (IVF). The present study evaluates follicular recruitment and outcome of IVF in patients treated with GnRH-a, starting in different phases of the menstrual cycle. Ovarian quiescence was achieved by s.c. injection of a GnRH-a (600 micrograms/day). Three groups of patients were randomly established. Patients in group 1 (n = 14) started GnRH-a treatment 4-7 days after ovulation. Women in group 2 (n = 15) started GnRH-a 8-10 days after ovulation. Patients in group 3 (n = 15) began the analogue 1-3 days after the onset of menses. Multiple follicular development was achieved by a combination of pure follicle-stimulating hormone and human menopausal gonadotrophin. Oocyte collection was performed 35 h after administration of human chorionic gonadotrophin. Luteolysis was successfully induced in 15% of cases in group 1 and 40% in group 2. Ovarian arrest was achieved in a significantly (P less than 0.01) shorter period of time in group 3 in comparison to groups 1 and 2. There was no difference between groups in the dose of gonadotrophins necessary to reach an optimal response. Patients in group 1 showed a significant decrease (P less than 0.05) in the number and size of follicles developed in comparison to groups 2 and 3. Fertilization and cleavage rates were similar in all three groups. The pregnancy rate was 40% in group 3, while it decreased to 14.3 and 13.3% in groups 1 and 2, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of thyroidectomy on serum and pituitary FSH in control and orchidectomized rats

The influence of hypothyroidism on both pituitary and serum FSH has been studied in male rats thyroidectomized in early stages of development. To know whether FSH alterations are produced by changes of the gonadal feed-back system or by a direct effect of thyroid hormones upon pituitary synthesis, estradiol, testosterone and testicular weight were measured. The result showed a decrease of biological and immunological activity of pituitary FSH in thyroidectomized rats. Serum FSH levels were also low. The deficiency of FSH production cannot be attributed to an alteration of the gonadal feed-back systems, since (1) in thyroidectomized rats, estradiol and testosterone were lower than in the controls, (2) signs of tubular atrophy were found in the testes and hence it could be expected that inhibin is low, and (3) in the absence of gonadal factors (induced by orchidectomy) thyroidectomized rats also showed a decrease of pituitary FSH. The present data suggest that the decrease of FSH can be attributed to a direct effect of thyroid hormones on pituitary FSH production.

Postnatal development of the renin-angiotensin system in thyroidectomized rats

Postnatal changes in plasma renin activity (PRA), plasma renin concentration (PRC), plasma renin substrate (PRS) and plasma angiotensin II concentration (AII) were studied in young thyroidectomized rats from the 4th to the 10th week of life. Although there were no differences in the PRA pattern between thyroidectomized and euthyroid animals, an increase in PRC from the 6th week of life, together with a reduction of the glomerular filtration rate (GFR) and an increase in the fractional excretion of sodium (FENa) from the 8th week of life, was observed in young hypothyroid animals. Moreover, in thyroidectomized animals, PRS and AII declined until the 10th week of age, while in euthyroid animals an increase of PRS and AII was observed between the 8th and 10th weeks of life. These results show that the changes in sodium renal handling following thyroidectomy could have an influence on the RAS components.

Evaluation of patients and partners 1 to 4 years after penile prosthesis surgery

One to 4 years after penile prosthesis implantation 52 men and 22 partners were interviewed personally. All except 4 patients were having intercourse on a regular basis. A quarter of the patients reported restriction in intercourse positions, possibly because of a smaller penis postoperatively, and 15 per cent reported decreased orgasm intensity. Six men had an undiagnosed prosthesis malfunction or they used an inadequate pumping technique, suggesting that prosthesis patients should be followed on a continuing basis. The 52 men had experienced 10 malfunctions with the prosthesis. Partial erections were reported by 69 per cent of the patients but this could be confirmed in only 1 of 10 with visual sexual stimulation testing. It is suggested that differences between prosthesis models are more a result of psychological, relationship and health factors than mechanical factors. Of the patients 79 per cent would undergo the operation again but only 59 per cent of the partners had no hesitations. The longer the postoperative period the more hesitations. A satisfaction score was used to measure patient satisfaction.

Effect of thyroid hormones on angiotensinogen production in the rat in vivo and in vitro

The influence of thyroid hormones on angiotensinogen production was studied in vitro and in vivo. In the in-vitro system, angiotensinogen production rate (APR) of monolayer cultures of rat hepatocytes in response to tri-iodothyronine (T3) and thyroxine (T4) was assayed. In the in-vivo system, plasma angiotensinogen concentration (PAC) and liver angiotensinogen content (LAC) were measured in hyper- and hypothyroid rats. In both thyroid dysfunctions, a significant decrease of PAC was found compared with that in control animals; however, LAC showed a significant increase in hyperthyroidism and a marked decrease in hypothyroidism. As PAC is dependent upon both angiotensinogen production by the liver and angiotensinogen degradation by renin, the decrease in PAC observed in hyperthyroidism could be due to an increase in plasma renin concentration, which would overcome the increased synthesis of liver angiotensinogen observed in these animals. In fact, addition of various concentrations of T4 or T3 to monolayer cultures of adult rat hepatocytes significantly enhanced APR. This increase was greater and started earlier with T3 (1196.1 +/- 143.7 (S.D.) pg/mg protein per 6-h incubation; significant differences at the third hour of incubation) than with T4 (858.3 +/- 88.2 pg/mg protein per 6-h incubation; significant differences at the sixth hour of incubation). In addition, a close dose-response relationship was found in the cultures supplemented with T3. The different time-course in the response elicited by T3 and T4 on APR could be a consequence of the necessary transformation of T4 into T3 to acquire biological activity.

Effect of various components of the renin-angiotensin-aldosterone system on angiotensinogen production in a monolayer culture of adult rat hepatocytes

A monolayer culture of adult rat hepatocytes was used to study the effect of various components of the renin-angiotensin-aldosterone system (angiotensin II, aldosterone and angiotensinogen), and intracellular sodium depletion (by ouabaine addition) on the angiotensinogen production rate. Normal hepatocytes synthesized linearly angiotensinogen for 6 h at a mean rate of 110 pg angiotensin I generated/mg intracellular protein each h. The addition of hydrocortisone (0.1 microM) to the culture medium significantly enhanced the angiotensinogen production after 2 h of incubation (P less than 0.05), being about 2-fold higher than normal control values at the 6th h of incubation. In contrast to this increase, the addition of angiotensin II (70 nM) to the medium produced a higher stimulatory effect on angiotensinogen synthesis, being the differences with the control significants after 1 h of incubation (P less than 0.01). At the 6th h of incubation, angiotensin II enhanced the angiotensinogen production over 2 fold in relation to the control group. No change in the angiotensinogen production rate was observed in monolayer culture of hepatocytes in the presence of aldosterone (1 microM), angiotensinogen (0.1 microM) or ouabaine (10 microM). These results provide further evidence that angiotensinogen synthesis is subject to a positive feed-back mechanism by angiotensin II, indicating that this mechanism takes place at physiological levels of plasma AII.

Postnatal development of renin-angiotensin system in rats

The changes occurring in several components of the rat renin-angiotensin system (RAS) were studied for the brief postnatal period, between the fourth and tenth week of life. The parameters were: plasma renin activity (PRA), plasma renin concentration (PRC), plasma renin substrate (PRS) and the plasma angiotensin II concentration (AII). A gradual decrease in PRA with age was noticed. Between the fourth and the eighth weeks of life, this was attributed to a corresponding decline in both PRC and PRS. However, between the eighth and tenth weeks, no changes in PRA could be detected, but PRC and PRS increased, perhaps as a consequence of the changes in renal function and the AII increase observed. In this second period, simultaneously with the RAS changes described, there was reduced sodium chloride excretion as the glomerular filtration rate (GFR) stabilized. The data presented suggest that this postnatal period is critical, in rats, for the maturation of the RAS component control mechanisms; they appear to be closely related to the development of the renal function.

Specific [3H]gamma-aminobutyric acid binding to vestibular membranes of the chick inner ear

To support a postulated neurotransmitter character of gamma-aminobutyric acid (GABA) in the vertebrate vestibule, [3H]GABA binding was measured in a crude membrane preparation of chick inner ear ampullary cristae. In the absence of divalent cations bound [3H]GABA was displaced by unlabeled GABA, muscimol or bicuculline, but it was not displaced by (+/-)-baclofen. A single population of [3H]GABA binding sites with an equilibrium constant of 19.4 nM and a maximum binding capacity of 0.58 pmol/mg protein was found. These results suggest the possible existence of a synaptic GABAA receptor in the chick inner ear membranes and sustain the neurotransmitter role of GABA in the chick vestibule.

Heterogeneity of thyroxine binding by serum albumins in normal subjects and patients with familial dysalbuminemic hyperthyroxinemia

The nature and properties of the T4-binding albumins in the sera of normal subjects and patients with the syndrome of familial dysalbuminemic hyperthyroxinemia (FDH) were investigated by means of isoelectric focusing in polyacrylamide gels. Albumins isolated from normal sera and sera of patients with FDH displayed multiple protein bands, with isoelectric points between 4.65 and 5.75, and protein patterns were the same in the two groups. In normal albumin, [125I]T4 was consistently localized in two bands, termed B1 and B2, whose isoelectric points (pIs) were 5.44 +/- 0.03 and 5.31 +/- 0.02 (mean +/- SE), respectively. Occasionally, binding of far smaller proportions of [125I]T4 was seen in two additional bands of lower pI (5.22 +/- 0.03 and 4.97 +/- 0.07), termed B3 and B4, respectively. In FDH albumin, [125I]T4 was also localized in four bands whose PIs were almost identical to those of B1-B4 in normal albumin. In FDH albumin, however, bands corresponding to B1 and B2 bound only a minor fraction of [125I]T4, the great majority being bound by bands corresponding to B3 and B4, especially the latter. Identity of the four T4-binding albumins in normal and FDH albumin was suggested by their virtually identical pIs in both types of albumin, by the emergence or intensification of the B3 band in both after extraction of endogenous T4, and by the finding that an 125I-labeled derivative of T4 used in a commercial one-step assay for serum free T4 was bound by the B4 band in both normal and FDH albumin, though more intensely in the latter. Treatment of FDH albumin with increasing concentrations of dithiothreitol (DTT; 0.1-5.0 mM) caused a progressive loss of [125I]T4 binding by B3 and B4, leaving [125I]T4 bound by B1 or B2, and had little effect on the binding of [125I]T4 by B1 and B2 in normal albumin. These effects of DTT appeared to correlate well with earlier dialysis studies at physiological pH which revealed that the same concentrations of DTT decreased or abolished the high affinity binding of T4 in FDH albumin but had little effect on the residual lower affinity binding of T4 in FDH albumin or that characteristic of normal albumin. These findings suggest that T4 binding patterns evident during isoelectric focusing of albumin at low pH have relevance to binding of T4 by albumins at physiological pH.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of two different experimental situations of hypothyroidism on serum aldosterone concentration and plasma renin in rats

When hypothyroidism is induced surgically in early steps of development in the rat, an increase in serum aldosterone concentration (AC), in absence of changes in plasma renin activity (PRA), is observed. In contrast, in propylthiouracil (PTU) induced hypothyroidism, in adult animals, both AC and PRA decrease. Potassium iodide (KI) or triiodo-L-thyronine (T3) administration to thyroidectomized rats restores AC to normal levels, increasing PRA during the latter treatment. A close relationship between AC and plasma renin concentration (PRC) is observed in these experimental situations. The decrease in urinary aldosterone concentration (ACu), and the relation found between AC/ACu ratio and T3 concentration, suggest that metabolic clearance of aldosterone might be related to peripheric T3 levels in thyroidectomized animals, treated with KI or T3. These observations support the hypothesis, previously reported, which suggests different mechanisms involved in the control of aldosterone and renin release during the two different types of hypothyroidism.

Moxalactam disodium-induced pulmonary hemorrhage

Fatal pulmonary hemorrhage occurred on the eighth day of moxalactam therapy. No other pharmacologic agent or obvious cause could be attributed to the hemoptysis. Moxalactam-induced pulmonary hemorrhage should be included in the differential diagnosis of an infiltrate when moxalactam is being administered.

Familial dysalbuminemic hyperthyroxinemia: a syndrome that can be confused with thyrotoxicosis

We investigated 15 euthyroid patients from eight families with a recently recognized syndrome, familial dysalbuminemic hyperthyroxinemia (FDH), that could be mistaken for thyrotoxicosis. The syndrome is characterized by elevations in serum thyroxine and the free-thyroxine index (FT4l), which are due to an abnormal serum albumin that preferentially binds thyroxine. This albumin has an abnormal binding site with a much greater affinity for thyroxine (relative to its affinity for triiodothyronine) than that of the hormone-binding site on thyroxine-binding globulin. Results of thyrotropin-releasing hormone and thyroid-suppression tests, as well as direct measurements of the free-thyroxine concentration by equilibrium dialysis, are normal in these patients, although the serum triiodothyronine concentration may be slightly elevated. Although its prevalence is uncertain, FDH may be more common than suspected; we have seen 26 cases within the past year.

[Comparison of adsorption capacity for FSH between kaolin and montmorillonite. Biological and immunological activity relation (author's transl)]

The adsorption capacity of urinary FSH has been studied comparatively with kaolin and montmorillonite, a new type of bentonite, never used before in gonadotrophin adsorption. To measure adsorption capacity, two different assay methods were used: bioassay (for biological activity of the kaolin and montmorillonite extracts) and radioimmunoassay (RIA) for the immunological activity of FSH in both extracts. From the present results a biological activity increase was observed in montmorillonite extracts, while no significant differences between immunological activity of FSH were found in either extract. These findings suggest that montmorillonite could replace kaolin in gonadotrophins extraction and purification methods.

[Infectious bovine rhinotracheitis (VHB-1). II. Physico-chemical properties of strain L-114]

The thermal stability, density gradient and morphological features of a recently isolated L-114 strain of infectious bovine rhinotracheitis virus were determined. Morphology studies showed an enveloped virus with 200 nm of total diameter, a core diameter of 90 nm and an icosaedral-type structure; purified preparations contained both complete and empty viral particles. More than 90% of the infectivity was lost after 15 hours at 37 degrees C; at 56 degrees C, inactivation was much faster, with a 3 log titer reduction, in 24 minutes. Density gradient studies in cesium chloride, carried out with virus concentrated on sucrose gradient, gave an estimated density of 1.25 g/ml for the purified virus, which fits with light herpesviruses.

Primeros datos sobre la duración del periodo de incubacion de los huevos de Tarentola mauritanica en Cordoba (sur de España)

Abstract

The time it takes the Tarentola mauritanica eggs to hatch in a locality in the South of Spain, counted from the moment of laying, has been much less than quoted in this respect so far for this species. The following results have been obtained: 4, 5, 8, 10 and 12 days (maximum). The possible generalization of this reproductive strategy is being discussed, as well as the possible advantages that it presents over the classical oviparity model.

N-Chloroacetyl 5-methoxytryptamine (isamide): a selective antagonist of 5-hydroxytryptamine in the rat uterus

Isamide, the N-chloroacetyl derivative of 5-methoxytryptamine, produced a dose-dependent competitive blockade of uterine contractions in vitro induced by 5-HT. The pA2 value for the 5-HT-isamide interaction was 4.42. The blockade was short-lasting and reversible; after recovery, a dose-dependent increase in the uterine sensitivity to 5-HT was found. The blockade proved to be selective to the 5-HT receptor. The simultaneous application of 5-HT plus isamide partially prevented the 5-HT-induced auto blockade phenomenon. In addition, isamide did not affect the contractile responses of the uterus to oxytocin or bradykinin or the contractile effects of the rat vas deferens to adrenaline.

Myoadenylate deaminase deficiency

Myoadenylate deaminase (adenosine monophosphate deaminase--AMPDA) was recently shown to be deficient in a group of patients by use of a histochemical and biochemical method based on the elaboration of ammonia by this enzyme as it deaminates 5' AMP. We have confirmed the utility of this histochemical method and the existence of persons deficient in AMPDA through the use of an unrelated assay technique. The lack of enzyme activity is not associated with any inhibitory activity in the muscles of patients with this disorder. The clinical diversity of these patients suggests that this lack may represent a normal variant or a subclinical state rather than an actual disease. The occurrence of AMPDA deficiency in both sexes points to possible autosomal inheritance.

[Infectious hepatitis. I. Presence of HBs antigen]

A prospective study in 268 patients of different pediatric ages affected with icteric hepatitis is presented, with a longitudinal follow-up of one year minimum. Different types of clinical evolution are described and related to the presence of HBs antigen. In 34 of the 268 patients HBs antigen was positive; in 20 of 28 patients with acute and long evolution, positivity of the antigen was transitory with an average of 46 days; in the remaining 8 of 28 patients it extended from 6 months to less than 2 years. The presence of HBs antigen is a risk that may be correlated with the tendency to extend the prolonged.

Increased disrupting effects of haloperidol on a conditioned avoidance response after 6-hydroxydopamine treatment

The influence of prior catecholamine depletion was studied on the behavioral depressant effects of haloperidol using a conditioned avoidance response. The butyrophenone disrupting effects on the avoidance behavior were significantly increased by 6-hydroxydopamine pretreatment.