Photocatalytic and free radical interactions of the heterocyclic N-oxide resazurin with NADH, GSH, and Dopa

Electron donating free radicals NAD(.), (.)CO2(-), MV(.)+, and e(aq)-, generated by pulse radiolysis, reduce resazurin (RNO) with rate constants of 1.9 x 10(9), 2.8 x 10(9), 4.8 x 10(9), and 2.3 x 10(10) M(-1) s(-1), respectively, neutral solution. The semireduced dye (RN(.)-O- disproportionates slowly to RN (resorufin) and RNO. There was little evidence that RN(.)-O- behaves as an oxidizing species capable of initiating chain reactions, for instance via oxidation of NADH to NAD(.). The oxidizing radicals GS(.), (.)OH, and N3(.) interact with RNO via complex consecutive processes, probably by addition-elimination reactions. Stable products generated upon oxidation of RNO by N3(.) exhibit a red-shifted absorption, but GS(.) and (.)OH also cause partial reduction to RN. Neither O2(.)- nor dopa semiquinone nor tyrosine phenoxyl radicals appear to interact with RNO. Radicals formed by reaction of (.)OH with (Gly)3 reduce RNO to RN with stoichiometry near two (gamma-radiolysis), and there is evidence (pulse radiolysis) for direct slow O-atom transfer from RNO to these species. Resazurin is highly photosensitive under anaerobic conditions in presence of H-atom donors like NADH, GSH, or dopa. Under aerobic conditions RNO becomes an efficient catalyst of red light induced photooxidation of these donors; the RN(.)-O- intermediate, formed in the photooxidative process, is apparently recycled to RNO by O2, and by other electron acceptors. Our results suggest that RNO can behave as a photoactive, free radical generating xenobiotic compound.

Synthesis of polymer-bound 6-mercuric carboxylate DOPA precursors and solid phase labelling method of 6-radioiodinated L-DOPA

In order to avoid separating unreacted mercury precursor and other mercury-containing compounds after the halodemercuration of a 6-mercury DOPA precursor, we developed a polymer-bound mercury precursor for the preparation of 6-halogenated DOPA. In this study, polymer-bound 6-mercuric carboxylate DOPA derivatives were synthesized from ion-exchange resin and Merrifield-type resin. Iododemercuration of polymer-bound 6-mercuric carboxylate DOPA derivatives gave higher yields (49-54%) compared with monomeric 6-mercuric trifluoroacetate protected DOPA. The radioiodination of the resin with no-carrier added iodine-125 afforded protected 6-[125I]I-L-DOPA with labelling efficiency of 92-97% with both polymer-bound 6-mercuric carboxylate DOPA derivatives.

Diagnostic studies with intravenous and intranasal growth hormone-releasing peptide-2 in children of short stature

GH secretion is primarily regulated by the hypothalamic-releasing hormones GHRH and somatostatin. Additionally, several neurotransmitters act at the hypothalamus and pituitary to modulate GH release. The agents commonly used in clinical practice to diagnose GH deficiency, such as arginine, insulin and L-dopa, act through the neural GH network. Many children with a poor GH response to conventional agents have a significant serum GH response to iv GHRH. GH-releasing peptides (GHRPs) are synthetic peptides that like GHRH act directly on pituitary somatotrophs to stimulate GH release. GHRP-2, an investigational drug, is one of the most potent members of the GHRP family. It has been shown to be effective in adults via the oral and intranasal as well as the iv route of administration. In this study, GH responses to GHRP-2 were compared with GH responses to other provocative agents in children of short stature. GHRP-2 was administered iv or intranasally to children with short stature. In the same subjects, GHRP-2 was administered iv in combination with GHRH. Twenty-four children undergoing evaluation for GH deficiency received at least one conventional agent (arginine, L-dopa/exercise, insulin) in addition to iv GHRH and GHRP-2. The GH responses to GHRH or GHRP-2 were similar in each child, and both were equally reliable predictors of pituitary reserve. The conventional agents used in GH testing were less likely to predict the capacity of the pituitary to release GH than were either GHRH or GHRP-2. There was no correlation between maximal GH response to standard tests with GH responses to GHRH or GHRP-2. A subset of the group of 21 children who had a robust response to iv GHRP-2 were later administered GHRH+GHRP-2 simultaneously. The GH response to GHRH+GHRP-2 was synergistic in this group of 12 children, similar to previously reported observations in adults of normal stature. Fifteen of the 21 children who had a robust response to the iv GH-releasing factors also received intranasal GHRP-2. All 15 of these children had a significant GH response to intranasal GHRP-2 over a dose range of 5-20 micrograms/kg per dose. The mean peak GH response to 15 micrograms/kg was 31.3 micrograms/L. The intranasal preparation was well tolerated.(ABSTRACT TRUNCATED AT 400 WORDS)

Maroteaux-Lamy syndrome associated with growth hormone deficiency

Growth retardation is a common feature of mucopolysaccharide storage disorders, mostly considered to be a consequence of skeletal changes, Maroteaux-Lamy disease is a subtype of mucopolysaccharidosis, demonstrating somatic changes and skeletal deformities. We present a case with Maroteaux-Lamy disease associated with growth hormone deficiency. Magnetic resonance imaging study revealed marked signal changes in white matter due to the storage in brain and empty sella appearance in sellar region. In the presence of empty sella syndrome, hypothalamic-pituitary dysfunction due to the storage material may have led to growth hormone deficiency in this patient. Therefore, we recommend patients with mucopolysaccharidosis, especially those who have growth retardation, to be evaluated by hormonal and radiological studies.

Changes in serum levels of IGF-I and IGFBP-3 in children with chronic renal failure

The significance of serum insulin-like growth factor I (IGF-I) and insulin-like growth factor binding protein 3 (IGFBP-3) levels in uremia is still controversial. In this study we measured serum IGF-I by immunoradiometric assay (IRMA) and IGFBP-3 levels by specific radioimmunoassay (RIA) in 28 children (aged 3-16 years) with end-stage (n = 14, on hemodialysis) and pre-terminal renal failure (n = 14) and in 15 age-matched healthy children. Thyroid function of the patients was also investigated and GH-stimulation tests with L-Dopa and insulin were performed. Neither IGF-I nor IGFBP-3 levels significantly correlated with mean height SDS for bone age or for chronological age in either non dialysis patients or pubertal (n = 10) or prepubertal patients (n = 18). These data was consistent with the concept that growth in CRF was not related to abnormalities in serum IGF-I or IGFBP-3 levels.

Pancreatic neuroendocrine tumors: diagnosis with PET

PURPOSE

To evaluate the use of carbon-11-labeled L-dihydroxyphenylalanine (L-DOPA) and hydroxytryptophan (5-HTP) in the diagnosis of pancreatic endocrine tumors with positron emission tomography (PET).

MATERIALS AND METHODS

Twenty-two consecutive patients with clinically and biochemically verified pancreatic endocrine tumors were examined with computed tomography (CT) and PET with L-DOPA alone (n = 16) or both C-11-L-DOPA and C-11-5-HTP (n = 6).

RESULTS

Tumor uptake of L-DOPA was found in 11 patients, eight of whom had metastatic disease. Heterogeneity of tracer uptake was noted among different lesions in the same patient (ie, high uptake in some lesions and low uptake in others). Results in patients examined with both L-DOPA and 5-HTP correlated well, but the uptake levels of 5-HTP were higher in two of three patients with positive findings. In two additional patients, CT enabled detection of tumors not detected at PET.

CONCLUSION

The current PET technique can be a valuable complement to CT in demonstration of functional pancreatic endocrine tumors, in particular, glucagonomas, but is less useful in detection of nonfunctional tumors.

A rapid and accurate method to realign PET scans utilizing image edge information

Movement during or between PET examinations is a common and serious problem. Consequently, there is a great need for rapid, accurate and robust methods to realign image sets.

METHODS

Derivative information from the image sets was used to extract areas containing edge information. Image similarity between a reference dataset and a misaligned dataset was evaluated for these areas. Powell's method for function minimization was used to find the set of translations and rotations along and around the axes that maximized image similarity. The method was validated by realigning image sets with a known misalignment. Image sets used for validation included brain studies using several different tracers and heart studies using labeled acetate or water.

RESULTS

The method was capable of labeled acetate or water.

RESULTS

The method was capable of realigning brain datasets using the same tracer with an accuracy of 0.2 mm and 0.2 degrees along and around all axes. The same accuracy was obtained for datasets with as few as a total of 800,000 counts. Brain studies utilizing different tracers with markedly dissimilar regional uptake patterns were realigned with an accuracy of 1.5 mm and 1.5 degrees. Heart studies using water or acetate were realigned with an accuracy of 0.2 mm and 0.4 degrees along and around all axes. Realignment of a heart study containing a large focal uptake defect against a dataset without defect produced errors no greater than 1.0 mm and 1.0 degree.

CONCLUSION

The use of derivative information provides a useful method to accurately realign PET image sets. It is rapid and noise-insensitive enough to allow for its routine use in dynamic studies.

Early diagnosis of Parkinson's disease

Early diagnosis of Parkinson's disease is often difficult. The insidious onset of the disease, its slow progression and the lack of laboratory tests to confirm the diagnosis contribute to this difficulty. Nevertheless, early diagnosis can be greatly facilitated by the systematic application of diagnostic clinical criteria and the selective use of radiological and laboratory tests.

[Disturbance of hypothalamic-pituitary hormone secretion in familial chorea-acanthocytosis]

An endocrinological study was performed dopaminergic regulation of the hypothalamic-pituitary axis of 3 patients with familial chorea-acanthocytosis (females, 38 to 47 years of age). All 3 patients exhibited low basal levels of triiodo-thyronine (T3), and 2 patients had a slightly elevated baseline plasma prolactin (PRL) level. The patients had a delayed plasma thyroid stimulating hormone (TSH) response and plasma PRL excessive response to thyrotropin releasing hormone (TRH), and a low plasma growth hormone releasing hormone (GRF) response to L-dopa. These TSH, PRL and GRF responses represent a secretion pattern due to a hypothalamic disorder, suggesting impaired regulation of hormone secretion by the dopaminergic system, primarily in the hypothalamus. In addition, an increased growth hormone (GH) response secretion following TRH (paradoxical response) was observed in 2 patients, suggesting that the pituitary was also involved. An oral glucose tolerance test (75g-OGTT) revealed a diabetic pattern in all 3 patients, indicating frequent association with impaired glucose tolerance.

Value and limits of pharmacological and physiological tests to diagnose growth hormone (GH) deficiency and predict therapy response: first and second retesting during replacement therapy of patients defined as GH deficient

There is currently a debate about the use of pharmacological and physiological tests to define GH deficiency and predict response to GH therapy. In addition, a good response to therapy has also been described in subjects without GH deficiency. For further information, we reevaluated GH secretion during replacement therapy in a group of children defined as GH deficient and examined response to therapy in the subjects subdivided according to secretion. One hundred eighty four children (113 boys and 71 girls) initially diagnosed with GH deficiency by means of pharmacological (peak < 8 micrograms/L after arginine and L-dopa tests) and physiological tests (mean nocturnal concentration < or = 3.3 micrograms/L during sleep test) underwent the same tests 2.8 +/- 1.1 yr after start of GH therapy. Sixty eight patients were retested 1.5 +/- 0.4 yr after first retesting. At diagnosis 122 subjects had pathological pharmacological and physiological tests (group A), 30 subjects normal sleep test with pathological pharmacological tests (group B), and 32 subjects pathological sleep test with normal pharmacological tests (group C). At diagnosis 140 subjects were prepubertal and 44 pubertal. To evaluate response to therapy in relation to GH secretion at diagnosis and at both retestings, a number of auxological parameters were calculated during treatment. At first retesting, 107 subjects (58.1%) changed initial group of diagnosis, 34 of whom (18.5%) presented normal secretion in both pharmacological and physiological tests (group D). At second retesting, 31 of the 68 subjects reexamined (45.6%) changed first test results, and 33 (48.5%) reverted to the initial group of diagnosis; none of the 6 subjects of group D maintained normal secretion. Although the percentage of normalized subjects was higher in pubertal subjects (36.4%; P = 0.0003) than prepubertal subjects (8.9%), puberty did not prevent a reduction of secretion in some subjects. Response treatment during the first year of therapy was similar in the various groups. GH secretion seems to change in both prepubertal and pubertal children diagnosed with GH deficiency when pharmacological and physiological tests are repeated over time. Moreover, such tests may not represent a reliable tool for predicting response to treatment. GH secretion normalization at retesting may not necessarily represent the end of a transient secretory defect.

X-ray characterization of melanins--I

The intrinsic local structure characterization of natural sepia melanin and L-dopa and tyrosine synthetic melanin powder has been carried out by X-ray diffraction using synchrotron radiation. The derived structure factor, S(q), shows six significant diffuse peaks within the q-range from 0.3 A-1 to 16 A-1 in the reciprocal space (q = (4 pi sin theta)/lambda, 2 theta is the scattering angle). The Fourier transform of S(q), which yields the radial distribution function (RDF), gives us information in real space of a 1.42 A distance averaged over the C-C, C-O and C-N bond lengths as well as peaks at 2.40-2.41 A, 3.67-3.71 A and 4.67-4.70 A discrete neighbor distances. There is a great similarity in the scattering intensity profiles of the natural and synthetic melanins indicating that the synthetically prepared material may be essentially similar to "real" melanin in its local atomic arrangements. An evidence of a prepeak at q congruent to 0.45 A-1 has been confirmed which indicates a preferred length scale of approximately 13-20 A that corresponds to the initial particle size in colloidal melanin solutions.

Excitotoxic lateral pallidotomy does not relieve L-dopa-induced dyskinesia in MPTP parkinsonian monkeys

We attempted to relieve the marked overactivity known to occur in the lateral segment of the globus pallidus (GPL) in L-DOPA-induced dyskinesia (LID) by unilateral stereotaxic ibotenic acid lesioning of the GPL in 4 monkeys with MPTP-induced parkinsonism. Two already dyskinetic animals were pallidotomized to counteract LID once established, while 2 L-DOPA-naive MPTP-treated animals were pallidotomized before L-DOPA was ever administered in an attempt to prevent the development of the process conductive to LID. Acutely after the lesion, more prominent akinesia (particularly in the contralateral limbs) with contraversive body deviation and circling behavior were seen for 48 h. Flexor posturing of the contralateral forelimb persisted to a variable degree. When L-DOPA treatment was resumed or instituted 1 week postoperatively, ipsiversive circling behavior occurred in all animals and contralateral dyskinesia worsened in 3, whether L-DOPA or a selective dopamine D2 agonist was administered. Lesions in these 3 cases were fairly restricted to the GPL histologically. One monkey kept L-DOPA-naive before pallidotomy never developed LID contralaterally to the lesion despite treatment for several months. The lesion this time involved the entire GP. The fact that ablation of the GPL worsened LID suggests that a complex rearrangement of the balance of functional capacity between the GP and the subthalamic nucleus takes place in LID which is not amenable to correction merely by a lateral pallidotomy. Our observations also suggest that functional redundancy exists in striatopallidal circuits and that no single pathway is responsible for LID.

Circulating growth hormone isoforms in girls with Turner's syndrome

To evaluate the presence of different GH isoforms in serum of girls with Turner's syndrome, we measured the serum GH content using RIAs with three different site-specific monoclonal antibodies (MAbs). We compared the results to those obtained with authentic GH and GH isoforms. Compared to pituitary GH (mol wt, 22K daltons) as the standard for all three MAbs, serum from girls with Turner's syndrome did not displace tracer [125I]GH equally with all three MAbs. The relative amounts of GH-immunoreactive material found in Turner's syndrome were different from the amounts observed in normal adults and most children with idiopathic short stature. The presence of GH, other than 22K GH, in serum from girls with Turner's syndrome was confirmed by affinity chromatography. The existence of different isoforms of GH, as shown by different cross-reactivity patterns with different MAbs to GH, may explain the conflicting results reported for GH secretion in girls with Turner's syndrome.

Twenty-four-hour osteocalcin, carboxyterminal propeptide of type I procollagen, and aminoterminal propeptide of type III procollagen rhythms in normal and growth-retarded children

The relationships between spontaneous variations in serum 24-h osteocalcin (OC), carboxyterminal propeptide of type I procollagen (PICP), and aminoterminal propeptide of type III procollagen (PIIINP) concentrations and GH secretion, measured as GH response to provocative pharmacologic stimuli and spontaneous GH secretion during 24 h, were evaluated in prepubertal normal children and in GH-deficient and GH-secreting short normal children (SNC). All the subjects showed a circadian rhythm in smoothed 24-h OC and PICP mean data with higher nocturnal values in comparison with diurnal values. Conversely, serum PIINP concentrations did not vary throughout the day. In children with classic GH deficiency and nonclassic GH deficiency, mean 24-h serum levels and smoothed 24-h mean data for OC, PICP, and PIIINP were significantly reduced (p < 0.001) with respect to age-matched controls. SNC showed mean 24-h OC concentrations similar (p = NS) to those we found in age-matched controls, but they had significantly lower (p < 0.001) diurnal 12-h mean data in comparison with controls. SNC also showed both 24-h PICP and PIIINP mean data and smoothed 24-h PICP and PIIINP mean data significantly lower (from p < 0.02 to p < 0.001) at all the time points of measurement in comparison with controls. Twenty-four-hour PICP and PIIINP mean data were positively related to spontaneous 24-h GH concentrations (r = 0.77, p < 0.005 and r = 0.69, p < 0.005, respectively) and growth velocity (r = 0.85, p < 0.005, and r = 0.70, p < 0.005, respectively), whereas 24-h OC mean data were not.(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical and fluorodopa positron emission tomographic findings in an asymptomatic carrier of the gene for dopa-responsive dystonia

We report cerebrospinal fluid monoamine metabolite analyses and 6-[18F]fluoro-1-dopa positron emission tomography (FD-PET) from an asymptomatic carrier of the gene for dopa-responsive dystonia. Cerebrospinal fluid homovanillic acid, tetrahydrobiopterin, and neopterin concentrations were reduced in this man and in his affected children. His FD-PET was normal, as we have previously found in dopa-responsive dystonia. Neurological function and FD-PET may be normal despite marked abnormality in dopamine metabolism.

Growth hormone and IGF1 profile in short children with osteopetrosis

Osteopetrosis is commonly associated with short stature. To identify the cause, 8 children with osteopetrosis and short stature were studied. One showed evidence of renal tubular acidosis, none showed evidence of anaemia, and all were clinically and biochemically euthyroid. Growth hormone profile was assessed using night sampling (8 patients), growth hormone provocative testing using insulin-induced hypoglycaemia (6 patients), and L-dopa-propranolol (8 patients). The mean nocturnal growth hormone values taken at 60 and 90 min after onset of sleep and at 4 a.m. were 5.5, 12.8, and 11.5 mu/L respectively. The peak stimulated growth hormone mean values with the insulin-induced hypoglycaemia (glucose 1.6-3.0 mmol/L, mean = 2.2) was 14 mu/L (range 7.3-24.5 mu/L) and with the L-dopa-propranolol was 25.6 mu/L (range 12.3-49 mu/L). IGF1 levels taken at 0 and 120 min of insulin-induced hypoglycaemia (0 min for L-dopa-propranolol), and at 120 min of L-dopa-propranolol, showed normal values for age. We conclude that: (1) growth hormone profiles in these children are normal; (2) tissue unresponsiveness to growth hormone and/or IGF1 is not likely to be the cause of short stature in children with osteopetrosis; and (3) osteopetrosis per se is not an indication for assessment of growth hormone status.

Growth hormone releasing hormone 1-44 NH2 and 1-40 OH levels in normal subjects during growth hormone stimulation tests

OBJECTIVE

Little is known about the relative circulating concentrations of growth hormone releasing hormone (GHRH) 1-44 NH2 and 1-40 OH in response to dynamic GH stimulation. We therefore studied the concentrations of growth hormone-releasing hormone (GHRH) 1-44 NH2 and 1-40 OH in the peripheral plasma of normal male subjects during GH stimulation tests.

DESIGN

Tests were performed at 0900 h after an overnight fast. Stimulation tests, commenced at 0 minutes, included alpha-adrenergic activation with adrenaline (10 micrograms/min from 0 to 30 minutes) following beta-blockade with propranolol (1.5 mg/min from -10 to 0 minutes), alpha 2-adrenergic activation with clonidine 150 micrograms i.v., insulin hypoglycaemia (0.15 U/kg soluble insulin), L-arginine infusion (30 g from 0 to 30 minutes), L-dopa (500 mg orally) and oral glucose (100 g).

SUBJECTS

Groups of healthy male volunteers aged 20-42 years, all within 10% of ideal body weight.

MEASUREMENTS

Serum GH and plasma GHRH 1-44 NH2 and 1-40 OH were measured at intervals for between 60 and 390 minutes, depending on the stimulation test.

RESULTS

There were no significant changes in either GHRH 1-44 or 1-40 following alpha-adrenergic activation with propranolol/adrenaline infusion, alpha 2-adrenergic activation with i.v. clonidine, insulin-induced hypoglycaemia or arginine infusion despite the expected rise in GH levels. After oral glucose, GH was initially suppressed with a late rise. There were no changes in GHRH 1-44 or 1-40 levels during either phase of this response. After L-dopa GH levels peaked at 90 minutes, 24.5 +/- 11.0 mU/l (mean +/- SEM). At 0 minutes GHRH 1-44 and 1-40 levels were 3.25 +/- 0.89 and 4.93 +/- 1.28 pmol/l respectively and rose in both cases, peaking at 60 minutes at 4.23 +/- 1.01 and 7.55 +/- 1.80 pmol/l (P < 0.05). At no time was there any evidence of differential secretion of GHRH 1-44 or 1-40.

CONCLUSIONS

We have confirmed previous studies demonstrating a small rise in GHRH before the GH response to L-dopa. However, in all other situations of pharmacological stimulation of GH release we were unable to detect any significant changes in GHRH 1-44 or 1-40 levels. It seems most likely that peripheral GHRH does not reflect hypothalamic secretion. As yet there is no evidence for differential release of GHRH 1-44 and 1-40.

Neuroendocrine responsivity to monoaminergic system probes in generalized social phobia

We examined neuroendocrine correlates of central monoamine function in patients with the generalized type of social phobia compared to healthy volunteers in order to test hypotheses of dopaminergic, noradrenergic, and/or serotonergic dysregulation in patients with this disorder. A double-blind, placebo-controlled, neuropharmacological challenge study was performed using probes for the serotonergic (fenfluramine), dopaminergic (levodopa), and noradrenergic (clonidine) systems. Twenty-one patients with DSM-III-R social phobia (generalized type) and 22 "never mentally ill" volunteers participated in the study after providing informed consent. Patients with social phobia had an augmented cortisol response to fenfluramine administration compared to the volunteers. In contrast, we found that neither the prolactin response to fenfluramine, the growth hormone or norepinephrine response to clonidine, nor the prolactin or eye-blink responses to levodopa, differed between patients with social phobia and healthy volunteers. The findings suggest that patients with social phobia may exhibit selective supersensitivity of serotonergic systems, but that dopaminergic and noradrenergic function appear normal. Further challenge studies with more specific serotonin probes before and after treatment may assist in the clarification of the pathophysiology of social phobia.

Improved tyrosinase activity stains in polyacrylamide electrophoresis gels

Mammalian tyrosinase exists in a variety of subcellular locations and maturation states that result from a complex post-translational processing with possible regulatory implications. So far, SDS-PAGE has proven to be the method of choice for the resolution of tyrosinase isoforms. However, the relatively poor sensitivity of the currently available specific activity stain based on incubation of the gels with L-dopa until the formation of melanin has severely limited the use of electrophoresis in regulation studies. Two alternative staining procedures are presented and discussed. The first one involves the fluorographic detection of radioactive melanin after incubation of the gels in the presence of L-[3-14C]-dopa. A similar method has already been used by others (Tsukamoto et al., 1992, Pigment Cell Res. [Suppl.] 2:84-89), but its performance has not yet been compared to the one of the dopa procedure. The sensitivity of this method can be varied by adjusting the isotopic dilution of the tracer and/or the time of exposure of the gel, but it is at least ten times higher than the one of the colorimetric stain. Moreover, the intensity of the bands is proportional to the initial tyrosinase activity over a wide range. Using this procedure, the activity present in the different subcellular fractions of melanocytes in culture can be easily detected. The second procedure involves the formation of a colored adduct between dopaquinone and MBTH.(ABSTRACT TRUNCATED AT 250 WORDS)

Diminished growth hormone responses to L-dopa in polycystic ovarian disease

OBJECTIVE

To investigate the GH secretion capacity in polycystic ovarian syndrome (PCOS).

DESIGN

Prospective.

SETTING

Reproductive endocrinology unit.

PATIENTS

Nineteen women with clinical and endocrinologic signs of PCOS were compared with 10 healthy weight-matched volunteers with normal menstrual rhythm and no history of endocrine or reproductive abnormality.

INTERVENTIONS

Standard GH reserve estimates were affected in all subjects using oral L-Dopa. The test was carried out after an overnight fast on cycle days 5 to 8 in menstruating subjects; the test was done randomly in patients with amenorrhea.

RESULTS

Both PCOS and control groups responded to L-Dopa over a 3-hour period with significant elevations in GH concentrations. The control group showed significantly higher values than the PCOS group at 90, 120, and 180 minutes.

CONCLUSION

The findings indicate that PCOS patients demonstrate a relative deficiency in GH reserve.

[Reevaluation of the I-dopa test in acromegaly: anatomo-clinical and prognostic correlations]

It is known that in acromegalic patients the GH secretion exhibits a pattern of response to various stimuli that differs from that observed in normal subjects. We have evaluated the paradoxical GH response to 1-Dopa in acromegaly, in order to clarify the relationships between this datum and the tumour size, the basal GH secretion, the GH response to TRH and the long-term prognosis. MATERIALS AND METHODS. 34 acromegalic patients, 12 men and 22 women, aged 35-70 yr, participated in this study. They were divided in 4 classes, according to Hardy's classification of pituitary neoplasias: (1) intrasellar microadenomas, < 10 mm (n = 8); (2) intrasellar macroadenomas, > 10 mm (n = 14); 3) adenomas with local expansion (n = 9); (4) adenomas with extrasellar expansion (n = 3). All patients underwent a 1-Dopa-test; 18 of them underwent a TRH-test. Basal postoperative GH and basal pre- and postoperative PRL levels were also determined. RESULTS. The basal preoperative GH values in all patients ranged between 16 and 278 ng/ml. 22 patients showed a paradoxical response to 1-Dopa, 12 were non-responders. The following results were observed in the different classes: [table: see text] Moreover, 10 subjects (56%) were TRH-responders (9 of them were also 1-Dopa-responders, 1 was non-responder) and 8 were TRH non responders (6 were 1-Dopa non-responders, 2 were 1-Dopa responders). Basal postoperative GH values were > 5 in 17 1-Dopa responders and in 9 non responders. Basal preoperative PRL levels were > 25 ng/ml in 7 1-Dopa responders and in 2 non responders. After surgery, basal PRL became normal in 5 responder patients. DISCUSSION. In a previous work we have correlated the paradoxical GH response to TRH with tumour size and GH levels, observing a higher percentage of paradoxical response in patients in class I and II and, postoperatively, lower GH levels in preoperative TRH responders. So, we have underlined the good prognostic feature of a preoperative paradoxical response. In this paper we have evaluated the paradoxical GH response to 1-Dopa in the different Hardy's classes and compared it with the GH levels and the GH response to TRH. The results show that a paradoxical response can be observed more frequently in small (class I) adenomas than in greater size ones, and in presence of lower GH basal levels. Moreover, a concordance between 1-Dopa and TRH tests can be observed. CONCLUSIONS. The results clearly indicate that the responses to dynamic GH tests should be evaluated considering the anatomic characteristics of the neoplasias. It could be suggested that the paradoxical response can be expressed only when hypothalamus-pituitary interactions are intact.

Effect of nondopaminergic drugs on L-dopa-induced dyskinesias in MPTP-treated monkeys

A group of four monkeys was rendered parkinsonian with the toxin MPTP. They were then treated chronically with L-DOPA/benserazide 50/12.5 mg/kg given orally daily for 2 months. This dose produced a striking antiparkinsonian effect, but all animals manifested dyskinesia. A series of agents acting primarily on neurotransmitters other than dopamine were then tested in combination with L-DOPA to see if the dyskinetic movements would be modified. Several drugs, including clonidine, physostigmine, methysergide, 5-MDOT, propranolol, and MK-801, markedly reduced the dyskinetic movements but at the cost of a return of parkinsonian symptomatology. However, yohimbine and meperidine reduced predominantly the dyskinetic movements. Baclofen was also useful in one monkey against a more dystonic form of dyskinesia. Atropine converted the dystonic movements into chorea.