Incidence of ventricular arrhythmias related to COVID infection and vaccination in patients with Brugada syndrome: Insights from a large Italian multicenter registry based on continuous rhythm monitoring

INTRODUCTION

Brugada syndrome (BrS) has a dynamic ECG pattern that might be revealed by certain conditions such as fever. We evaluated the incidence and management of ventricular arrhythmias (VAs) related to COVID-19 infection and vaccination among BrS patients carriers of an implantable loop recorder (ILR) or implantable cardioverter-defibrillator (ICD) and followed by remote monitoring.

METHODS

This was a multicenter retrospective study. Patients were carriers of devices with remote monitoring follow-up. We recorded VAs 6 months before COVID-19 infection or vaccination, during infection, at each vaccination, and up to 6-month post-COVID-19 or 1 month after the last vaccination. In ICD carriers, we documented any device intervention.

RESULTS

We included 326 patients, 202 with an ICD and 124 with an ILR. One hundred and nine patients (33.4%) had COVID-19, 55% of whom developed fever. Hospitalization rate due to COVID-19 infection was 2.76%. After infection, we recorded only two ventricular tachycardias (VTs). After the first, second, and third vaccines, the incidence of non-sustained ventricular tachycardia (NSVT) was 1.5%, 2%, and 1%, respectively. The incidence of VT was 1% after the second dose. Six-month post-COVID-19 healing or 1 month after the last vaccine, we documented NSVT in 3.4%, VT in 0.5%, and ventricular fibrillation in 0.5% of patients. Overall, one patient received anti-tachycardia pacing and one a shock. ILR carriers had no VAs. No differences were found in VT before and after infection and before and after each vaccination.

CONCLUSIONS

From this large multicenter study conducted in BrS patients, followed by remote monitoring, the overall incidence of sustained VAs after COVID-19 infection and vaccination is relatively low.

COVID-19 impact on the decision process of the Italian Medicine Agency: a quantitative assessment

Background

Since the COVID-19 pandemic has placed more attention on drugs' approval process and the importance of rapid decision-making in the healthcare sector, it is crucial to assess how time to market (TTM) of drugs varied.

Objective

To estimate the impact of the COVID-19 pandemic on TTM of drugs in Italy.

Methods

An IQVIA database was used to retrieve information on drugs that obtained positive opinion from the Committee for Medicinal Products for Human Use between January 2015 and December 2021. The available observations were divided into three groups (Pre COVID, Partially COVID, and Fully COVID) according to the timing of their negotiation process. Differences in average TTM among the three groups were analyzed in three steps: (1) descriptive statistics; (2) univariate analysis; (3) multivariate analysis, using a matching estimator.

Results

A total of 363 unique combinations of molecule and indication met the inclusion criteria: 174 in the Pre COVID group, 69 in the Partially COVID group, and 123 in the Fully COVID group. Descriptive statistics and univariate analysis found a statistically significant difference in TTM among the three periods, with average TTM increasing during the pandemic (+136 days, p = 0.00) and then decreasing afterward (-23 days, p = 0.09). In the matching analysis, results for the Partially COVID period were confirmed (+108 days, p = 0.00) while results for the Fully COVID period lost significance but maintained a negative sign.

Conclusions

The results suggest that after an adjustment phase in the Partially COVID period, a return to the status quo was reached.

Multivariate tools to investigate the spatial contaminant distribution in a highly anthropized area (Gulf of Naples, Italy)

The Gulf of Naples located in a high anthropized coastal area is subjected to an infrastructural intervention for the installation of a submarine power pipeline. In order to evaluate the distribution of contaminants in the seafloor sediments, a preliminary study has been conducted in the area using multivariate techniques. The statistic approach was performed to gain insights on the occurrence of organic and inorganic contaminants within the area, aiming to identify the relevant hot spots. Three geographical sub-areas influenced by different contaminant association were recognized: Torre Annunziata (TA), Capri (CA), and middle offshore (MO). TA and CA resulted marked by a severe contamination pattern due to anthropogenic pressures. In addition, the influence of the depositional basin in governing the contamination trend has been pointed out. The supervised technique PLS_DA resulted to be a powerful tool in addressing the complexity of the huge dataset acquired during the marine survey, highlighting the main trends in the variability of quality indicators, orienting thus the deeper investigations during follow-up monitoring activities.

Habitat heterogeneity: A confounding factor for the effect of pollutants on macrobenthic community in coastal waters

Discrepancies were found between Ecological Status of sediments evaluated though the analysis of macrobenthic community and chemical analyses along a heavily trafficked and contaminated maritime seaway in Tyrrhenian Sea. Chemical analyses showed some sites highly contaminated by PAHs and metals with values exceeding thresholds for Good Chemical status and representing potential toxicological risk for benthic animals. Conversely, macrobenthic communities were highly rich and diverse, with Ecological Status (through M-AMBI) Good and High at each site. Sampling depth, total organic carbon, and total nitrogen were the major factors influencing biotic indices (AMBI, M-AMBI, S, H), even if concentrations of PAHs and metals (V, As, and Fe) contributed in explaining a part of indices variability. Habitat heterogeneity of sampled sites is likely acting as a confounding factor for two reasons: (1) high variability of environmental parameters leads to high richness and diversity, to which M-AMBI is sensitive, and (2) environmental parameters explained part of the variability of indices, together with contaminants. Our results suggested the importance of considering natural variability as a fundamental step of environmental impact assessment, for the correct interpretation of biotic indices.

Sacubitril/valsartan therapy and supraventricular arrhythmias detected through remote monitoring in heart failure patients

Funding Acknowledgements

Type of funding sources: None.

Background

Sacubitril/valsartan (S/V) has demonstrated a significant benefit in decreasing mortality and morbidity in patients with heart failure with reduced ejection fraction (HFrEF) when compared to angiotensin inhibition. Recent studies demonstrated that the benefits of S/V encompass a positive cardiac remodeling, leading to a reduction of ventricular arrhythmias. The effect of S/V on the supraventricular arrhythmic burden is still unknown. 

Purpose

To evaluate the effect of sacubitril/valsartan on the supraventricular arrhythmic burden in HFrEF patients with an implantable cardioverter defibrillator (ICD) or cardiac resynchronisation therapy-defibrillator (CRT-D) and remote monitoring. 

Methods

The SAVE THE RHYTHM is a multicentre, observational, prospective registry is enrolling all patients with HFrEF, ICD or CRT-D actively followed through remote monitoring and starting treatment with sacubitril/valsartan. All patients are followed-up at least one year after sacubitril/valsartan start. The primary endpoint is the number of sustained atrial tachycardia or AF (AT/AF). Secondary endpoints include incidence of AT/AF in the total population, total burden of AT/AF (defined as the percentage of time in AT/AF per day), mean number of premature ventricular contractions (PVC) per hour and percentage of biventricular pacing per day (in patients with CRT-D).  All primary and secondary endpoints are collected through remote monitoring.

Results

At the time of the second ad interim analysis, 188 patients (85.2% male, age 68 ± 10 years) were consecutively enrolled. In patients without permanent AF, treatment with S/V was associated with a reduced incidence of AT/AF episodes,  which changed from 32.6% (before treatment start) to 24.3%, 20.5% and 6.9% according to the sacubitril/valsartan dose (24/26 mg, 49/51 mg and 97/103 mg respectively; p= 0.041). A significant decrease in the median annual number of AT/AF episodes was also seen in these patients (16/year before treatment; 12/year at 24/26 mg; 6/year at 49/51 mg and 1/year at 97/103 mg; p = 0.046). No significant differences were reported in terms of PVC or biventricular pacing (all p = NS). Patients with permanent AF experienced no benefits from sacubitril/valsartan therapy in terms of arrhythmic burden reduction. No new diagnosis of clinical AF was made after starting treatment with sacubitrl/valsartan in all patients.

Conclusions

Preliminary data suggest that therapy with S/V could reduce the episodes of AT/AF in patients with HFrEF and remote monitoring, and the benefit seems related to the maximum tolerated dose of S/V. No positive effect has been noted in patients with permanent AF.

Types, occurrence and distribution of microplastics in sediments from the northern Tyrrhenian Sea

This is the first survey to investigate microplastic contamination in the Northern Tyrrhenian seafloor, along a 31 km-long transect from the port of Piombino (Tuscany) to the port of Portoferraio (Elba Island). Plastics extracted from 58 sediment samples were counted and identified by Fourier-transform infrared spectroscopy (FTIR). Plastic pollution occurred in sites closer to ports as well as in offshore stations. Microplastics (1-5 mm) accounted for over 80% of particles. For all samples, the dominant microplastic type was filaments, followed by fragments and films. Six polymers were identified: nylon, polyurethane, polyethylene, and polyethylene terephtalate were the most common. This part of the Tyrrhenian Sea is a busy shipping route connecting the mainland to the Elba Island, with thousands cargo and passenger ships passing by per year. Our data constitute a baseline for microplastic research in the Tyrrhenian seafloor.

Is the microplastic selective according to the habitat? Records in amphioxus sands, Mäerl bed habitats and Cymodocea nodosa habitats

This study estimated for the first time the total loads of plastic litter (macro- meso- and micro-plastics) in sediments of different habitat types from the Northern Adriatic Sea. Samples were collected in March 2016. The sampling sites were settled in shoreline, on the C. nodosa bottoms, Amphioxus sands, and Mäerl bed habitats. Microplastics items were present in all sampling site and ranging within 137-703 items/kg d.w. from Mäerl bed habitat to the shoreline. In C. nodosa bottoms 170 items/kg d.w. were found, while in Amphioxus sands were recorded on average 194 items/kg d.w. Due to the absence of statistical associations among litter levels and abundance of B. lanceolatum in the study area, this research present the needs to develop a new method and more research to for the evaluation of how much the interrelation between sensible habitats and microplastic exist.

Small plastic debris in sediments from the Central Adriatic Sea: Types, occurrence and distribution

This is the first survey to investigate the occurrence and extent of microplastic contamination in sediments collected along a coast-open sea 140km-long transect in the Central Adriatic Sea. Plastic debris extracted from 64 samples of sediments were counted, weighted and identified by Fourier-transform infrared spectroscopy (FT-IR). Several types of plastic particles were observed in 100% of the stations. Plastic particles ranged from 1 to 30mm in length. The primary shape types by number were filaments (69.3%), followed by fragments (16.4%), and film (14.3%). Microplastics (1-5mm) accounted for 65.1% of debris, mesoplastics (5-20mm) made up 30.3% of total amount, while macro debris (>20mm) accounted for 4.6% of total plastics collected. Identification through FT-IR spectroscopy evidenced the presence of 6 polymer types: the majority of plastic debris were nylon, polyethylene and ethylene vinyl alcohol copolymer. Our data are a baseline for microplastic research in the Adriatic Sea.

Primary pigmented micronodular disease of the adrenals

Primary pigmented micronodular disease is a peculiar form of ACTH-independent Cushing's syndrome characterized by the familial occurrence, the frequent association with malformations and the pathological adrenocortical picture consisting in micronodules with cellular deposition of lipofuscinic pigment. We describe here a case occurring in a 14-year-old girl.

Growth hormone responses to pyridostigmine in normal adults and in normal and short children

There is evidence indicating that the cholinergic system positively modulates GH release probably by inhibiting somatostatinergic tone. In the present study, the effects of cholinergic enhancement by pyridostigmine, (PD), a cholinesterases inhibitor, on GH release in normal adults (n = 14) (NA) and in both normal (n = 5) (NC) and short children (n = 19) (SC) with familial short stature (n = 7) or constitutional growth delay (n = 12) were studied. In SC the insulin hypoglycaemia (IH)-induced GH increase was also studied. In both NC and SC 60 mg orally PD induced a significant GH increase with mean peak at 90 min (mean +/- SEM 11.0 +/- 2.2 ng/ml in NC and 11.2 +/- 2.3 ng/ml in SC). The GH areas under response curve (AUC) were 379.3 +/- 76.6 and 327.8 +/- 43.2 ng/ml/h in NC and SC respectively. In NA 120 mg orally PD induced a significant GH increase with mean peak at 120 min (5.1 +/- 1.1 ng/ml) which was significantly lower (P less than 0.05) than that observed in both NC and SC. This statistical difference was strengthened by evaluating AUC (NA:205.6 +/- 33.7 ng/ml/h, P less than 0.05 vs NC and SC). The correlation of drug dosage with body area ruled out that this difference could be related to the different PD dose in adults and children. In SC, IH induced a GH increase significantly lower than that observed after PD (GH peak 7.8 +/- 0.6 vs 16.4 +/- 1.9 ng/ml P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Enhancement of cholinergic tone by pyridostigmine promotes both basal and growth hormone (GH)-releasing hormone-induced GH secretion in children of short stature

Increased cholinergic tone induced by pyridostigmine (PD) increases basal plasma GH levels and potentiates the GH response to GHRH in normal adults. In this study the effects of PD (60 mg, orally) on both basal and GHRH (1 microgram/kg)-induced GH secretion in seven children with familial short stature (FSS), six with GH deficiency (GHD) and 10 with constitutional growth delay (CGD) were studied and compared with results obtained by stimulation with insulin-induced hypoglycemia (IH) and GHRH alone. The mean peak plasma GH levels were variable, but individual values were frequently low in all groups after both IH [FSS, 9.7 +/- 1.3 (+/- SEM) ng/mL; GHD, 1.6 +/- 0.4 ng/mL; CGD, 7.0 +/- 0.8 ng/mL] and GHRH (FSS, 23.8 +/- 6.6 ng/mL; GHD, 11.1 +/- 5.8 ng/mL; CGD, 15.1 +/- 4.5 ng/mL) administration. PD induced GH responses (FSS, 14.5 +/- 1.6 ng/mL; GHD, 3.8 +/- 0.8 ng/mL; CGD, 18.3 +/- 3.2 ng/mL) that in many children in the FSS and CGD groups were higher than those after IH and GHRH treatment. PD clearly increased the GH response to GHRH in all children [FSS, 69.5 +/- 9.4 ng/mL (P less than 0.01 vs. other stimuli); GHD, 18.0 +/- 7.5 ng/mL; CGD, 50.0 +/- 8.5 ng/mL (P less than 0.01 vs. other stimuli)]. We conclude that in children with short stature, as in adults, enhancement of cholinergic tone increases both basal and GHRH-induced GH secretion, and that PD plus GHRH is the best provocative stimulus for evaluating the somatotroph response.

Effects of a new long-acting form of bromocriptine on tumorous hyperprolactinemia

Recently, a new long-acting form of bromocriptine (Parlodel LA, Sandoz) has been developed and it has already been found to be effective in lowering plasma PRL levels in normal volunteers and postpartum women. This work reports the clinical, hormonal and radiological effects of a single 50 mg dose of long-acting bromocriptine in 10 patients with tumorous hyperprolactinemia (2 microprolactinomas, 6 macroprolactinomas, 1 acromegaly and 1 nonsecreting macroadenoma). A rapid and long-lasting (28 days) normalization of PRL levels was observed in patients with microprolactinoma, acromegaly and nonsecreting adenoma. None of the 6 patients with macroprolactinoma underwent normalization of plasma PRL, but the latter was markedly reduced (61-80% of basal levels). A second injection of the drug in 5 macroprolactinoma patients induced a further reduction of plasma PRL levels in 2 of them. No changes in the tumor size were observed either after the first or the second injection of long-acting bromocriptine in any of the patients. This injectable form of bromocriptine induced nausea and/or mild hypotension lasting a few h in 4 of the 10 patients and was better tolerated than the oral form as regards both the duration and intensity of the side effects. Thus, as this drug has proved to be efficacious and well tolerated by the patients, this long-acting form of bromocriptine may be a valid therapeutical approach for initiating medical treatment of patients with prolactinoma.

Long term treatment with oral single administration of bromocriptine in patients with hyperprolactinemia

In the treatment of hyperprolactinemia bromocriptine is generally administered in 3 daily doses during the day. Due to the limited compliance of patients under this long term regimen, in 16 hyperprolactinemic patients we investigated the efficacy and tolerability of the treatment with this dopaminergic drug administered as a single evening dose. This dose was the same which the patients had been assuming previously on a tid basis. Chronic treatment (4-12 months) with an oral single evening dose of bromocriptine is able to control plasma PRL at least as well as the traditional tid regimen (2.8-21.6 ng/ml vs 1.2-31.8 ng/ml). Furthermore, during this single dose regimen the side effects were of lesser intensity and extent. Since the compliance of the patients with the single dose regimen was very good and the efficacy the same in reducing plasma PRL and controlling the clinical manifestations with a lower rate of side effects, we suggest to extend this regimen to all patients with hyperprolactinemia treated with bromocriptine after successful reduction of plasma PRL levels is obtained.

Potentiation of cholinergic tone by pyridostigmine bromide re-instates and potentiates the growth hormone responsiveness to intermittent administration of growth hormone-releasing factor in man

It is known that in normal subjects repeated administration of the growth hormone-releasing factor (GRF) induces a state of partial refractoriness of the somatotropes to GRF. Studies were conducted to verify whether the cholinergic system plays a role in the mechanism(s) underlying the reduced GH responsiveness to the neuropeptide. In five healthy men, the GH response to three consecutive injections of GRF (50 micrograms iv), administered at 2 h intervals, was considerably blunted after the second and third GRF bolus. Administration of the inhibitor of cholinesterase, pyridostigmine bromide (120 mg orally) 30 min before the second GRF bolus, not only restored but greatly potentiated the GH responsiveness to the second GRF bolus. The GH response to the third GRF bolus was not apparently influenced by pre-treatment with pyridostigmine. These data reinforce the view that cholinergic neurotransmission plays an important role in the control of GH secretion in human.

Comparison between pituitary computed tomographic findings and tests of hypothalamo-pituitary function in 72 patients with hyperprolactinaemia

To verify the diagnostic capacity of some dynamic tests of the prolactin (Prl) secretion, the findings obtained by high-resolution computed tomography (CT) were compared with results obtained from tests using nomifensine (NOM) domperidone (DOM) and thyrotrophin-releasing hormone (TRH) in 72 patients with pathological hyperprolactinaemia. None of the patients with tumours had a positive Prl response to NOM or to DOM administration; however, a positive response to these tests was present in only 24 and 41%, respectively, of the patients with normal CT picture. The results of TRH testing were similar to those obtained with DOM. Different neuroendocrine patterns were disclosed by comparing pituitary Prl and thyrotrophin (TSH) responses to DOM: 1) some subjects had a reduced Prl response together with an exaggerated or normal TSH response to DOM; they comprised patients with tumour, empty sella, and normal CT picture; 2) other patients with normal CT picture had a positive Prl and a normal TSH response to DOM. These results demonstrate that a negative Prl response to NOM and DOM characterizes all patients with adenoma; however, the tumour-like responses in patients with no visible tumours seem to reduce the diagnostic value of these tests, unless the latter may predate the radiological appearance of an adenoma. On the other hand, a positive Prl and a normal TSH response to DOM exclude the presence of a pituitary tumour. This diagnostic finding is strengthened by the positive response also to NOM. Whatever may be the diagnostic validity of dynamic tests, they provide sound information on the functional state of dopamine neurotransmission.

Cholinergic involvement in the growth hormone releasing hormone-induced growth hormone release: studies in normal and acromegalic subjects

To throw light onto the mechanism(s) by which the cholinergic system influences growth hormone (GH) release, the effects of two muscarinic receptor blockers, pirenzepine and atropine, and of an acetylcholinesterase inhibitor, pyridostigmine bromide, on the GH response to GHRH-44 were studied in 19 normal volunteers. Moreover, the effects of pirenzepine administration on plasma GH levels both in basal conditions and after stimulation by GHRH-44 and TRH were studied in 9 acromegalics. Both pirenzepine (0.6 mg/kg i.v., 5 min before GHRH) and atropine (1 mg i.m., 15 min before GHRH) blunted the GH response to GHRH (1 microgram/kg i.v. bolus) (area under the response curve, AUC: 81.3 +/- 17.3 vs. 481.2 +/- 211.3 ng/ml/h for pirenzepine and 100.2 +/- 27.0 vs. 364.7 +/- 81.0 ng/ml/h for atropine; p less than 0.01). Pyridostigmine (120 mg orally, 30 min before GHRH) induced a variable but significant (p less than 0.02) rise in basal plasma GH levels and, furthermore, an unequivocal potentiation of the GH response to GHRH (AUC: 1044.6 +/- 245.3 vs. 481.2 +/- 211.3 ng/ml/h; p less than 0.01). In all but one acromegalics 0.6 mg/kg i.v. pirenzepine was unable to modify the basal GH levels whilst it showed a variable inhibitory effect on the GH response to GHRH. The GH response to TRH (200 micrograms i.v. bolus) was instead unmodified by pirenzepine. In conclusion, muscarinic receptor blockade inhibits while cholinergic potentiation seems to positively modulate the GH response to GHRH. Therefore, the cholinergic system seems to positively modulate the GHRH effect on somatotrophs.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolactin and TSH responses to both domperidone and TRH in normal and hyperprolactinaemic women after dopamine synthesis blockade

A study of the effect of alpha-methyl-1-tryosine (metyrosine) blockade (2 g/d for 2 d) of dopamine (DA) synthesis on the PRL and TSH response to domperidone (DOM) and TRH in normal women and subjects with pathological hyperprolactinaemia is reported. In the normal subjects, there was a marked increase in basal PRL (51.7 +/- 11.1 vs 5.7 +/- 1.0 ng/ml) and the PRL and TSH responses to DOM were abolished. The PRL response to TRH was also reduced. In the hyperprolactinaemic subjects, metyrosine had no effect on basal PRL nor on the virtually non-existent PRL response to DOM, whereas it abolished the exaggerated TSH response. The conclusion is drawn that the response of both PRL and TSH to DA receptor blockers is really dependent upon DA inhibitory tone. A fall in this tone can also be postulated as responsible for the hyporesponsiveness of PRL to DOM frequently observed in pathological hyperprolactinaemia. In addition, the fact that metyrosine also abolished the exaggerated TSH response to DOM shows that the latter is totally dependent on enhanced DA inhibition of the thyrotrophs. Lastly, the reduced PRL response to TRH after metyrosine indicates that DA partly determines the ability of the lactotrophs to respond to TRH.

Effect of metoclopramide, domperidone and apomorphine on GH secretion in children and adolescents

The way in which the dopaminergic system controls GH secretion in infancy and adolescence was investigated by studying the effects on GH of a specific dopaminergic agonist apomorphine, and two antagonists, metoclopramide (MC), which can and domperidone (DOM), which cannot cross the blood-brain-barrier, (BBB), in 14 males and 6 females aged 8-17 years. Treatment with both antagonists was followed by a marked increase in Prl, whereas only MC stimulated GH secretion, suggesting that this action must occur inside the BBB if it is linked to antidopaminergic properties. GH secretion was also stimulated by apomorphine, which acts at the central level. The paradox posed by the presence of a central effect on GH secretion derived from both an agonist and an antagonist of the dopaminergic receptors is discussed.

Effect of naloxone on gonadotropin secretion before and after testosterone in Klinefelter's syndrome

A study was performed on eight subjects with Klinefelter's syndrome to assess the relation between gonadal hormones and opioid inhibition of gonadotropin secretion through comparison of their gonadotropin response to naloxone (NAL) (0.3 mg/kg; 1/3 bolus iv. at time 0 and 2/3 iv. for 120 min) before and after testosterone propionate (TP) 100 mg/day im. for 5 days. Under basal conditions, NAL failed to induce a significant change in LH levels. After TP, however, despite unchanged basal LH levels (mean +/- S.E.M.: 27.0 +/- 3.4 vs 21.2 +/- 3.21 microU/ml), LH significantly increased in response to NAL. FSH did not respond to NAL either before or after TP administration, though FSH levels were significantly reduced by TP. These findings suggest that in man, as in animals, gonadal hormones regulate opioid inhibition of LH secretion. The negative feedback of testosterone and its ability to activate opioid inhibiting tone may be dissociated, in keeping with the view that gonadal hormones control gonadotropin secretion through the activation of distinct, albeit concomitant, mechanisms.

Blockade of hp-GRF-40-induced GH release in normal men by a cholinergic muscarinic antagonist

In five healthy young men, pretreatment with the cholinergic muscarinic antagonist pirenzepine (0.6 mg/kg iv) almost completely abolished the rise in plasma growth hormone (GH) elicited by an iv bolus injection of 1 microgram/kg human pancreatic GH-releasing factor 1-40 (hp-GRF-40). These data demonstrate that cholinergic receptor sites involved in GH-releasing mechanisms do not interact with GRF-secreting structures in the central nervous system. A mechanism mediated via hypothalamic release of somatostatin or, alternatively, a direct pituitary site of action, can be postulated for the blocking effect of pirenzepine.

Estrogenic treatment does not modify the TSH and PRL responses to domperidone and TRH in patients with tumoral hyperprolactinemia

To verify if the low estrogen regimen could condition the TSH hyperresponsivity and PRL hyporesponsivity to antidopaminergic drugs seen by us and others in patients bearing prolactinoma, the effect of ethynilestradiol treatment (50 micrograms/day/14 days) on TSH and PRL responses to domperidone in 6 women with tumoral hyperprolactinemia and hypoestrogenemia were studied. Estrogenic treatment was unable to modify the TSH and PRL responsiveness either to domperidone and TRH. These data do not support the hypothesis that hypoestrogenemia could cause the peculiar TSH and PRL pattern in response to antidopaminergic drugs, in patients bearing prolactinoma. Also the TRH releasable pool of TSH and PRL in these patients seems to be unaffected by estrogenic treatment.

Defective regulation of prolactin secretion after successful removal of prolactinomas

The PRL response to nomifensine (Nom), an indirect DA agonist; domperidone (Dom), a DA receptor antagonist; and TRH, which directly stimulates the PRL-secreting cells, was evaluated 2-53 months after surgery in 13 patients in whom successful removal of a prolactinoma had resulted in normal serum PRL levels and return of regular menses or libido and potency. In addition, the pattern of TSH secretion in response to Dom and the spontaneous rise in plasma PRL of 6 cured patients during pregnancy were evaluated. Nom induced an inconsistent decrease in basal PRL levels, a pattern contrasting with that in healthy women in whom plasma PRL was markedly suppressed after administration of the drug. Dom and TRH elicited a significant rise of basal PRL levels, but the rise was markedly lower than that occurring in the control group. The TSH increment after Dom treatment was lower than that before surgery, though higher than that in the controls. Evaluation of individual patients showed that only one patient had a normal PRL response to either Nom or Dom, while the TSH response to the latter returned to normal in five of seven patients. During pregnancy, plasma PRL rose inconsistently in the patients, and PRL levels were generally lower than those in normal pregnant women. These results suggest the presence of an abnormality in the dopaminergic mechanism(s) of PRL control before and after adenomectomy or, less likely, the existence of impaired pituitary function or reserve.

Effects of naloxone on the insulin and GH responses to alpha-adrenergic stimulation with clonidine

To find if endorphins can influence hormonal responses mediated by noradrenergic pathways, we examined the effects of naloxone, an opiate receptor blocker, on the GH and insulin responses to clonidine, a drug which acts by stimulation of alpha-adrenergic receptors. Intravenous clonidine (0.15 mg in 10 min) induced a significant fall of plasma insulin and a marked increase of plasma GH. Intravenous naloxone (bolus of 1.6 mg followed by 50 micrograms/min) did not change the insulin response to clonidine, and seemed to induce only a slight delay in the GH response.

Glucagon-induced increase in plasma potassium levels in type 1 (insulin-dependent) diabetic subjects

To investigate the hypothesis that in Type 1 (insulin-dependent) diabetes the increase in plasma potassium during decompensation may be due to a rise in glucagon concentrations, we have measured plasma glucose, potassium and glucagon levels in five diabetic patients during two tests with 0.154 mol/l saline or somatostatin (500 micrograms/h) performed on two successive days. The patients were maintained normoglycaemic overnight by means of a continuous insulin infusion. After insulin withdrawal during the saline infusion, glucose and potassium levels rose markedly (delta maximum: glucose, 12.0 +/- 1.5 mmol/l; potassium, 0.73 +/- 0.12 mmol/l), while glucagon showed a slight, but significant increment (delta maximum: 10.6 +/- 1.0 pmol/ml, p less than 0.05). The potassium increment was not mediated by a reduction in blood pH. Somatostatin abolished the rise in glucagon concentration and simultaneously markedly inhibited the rise in potassium and glucose levels. It is concluded that in acute insulin deficiency, glucagon could be one of the factors that contributes to hyperkalaemia.

Reciprocal pattern of the TSH and PRL responses to dopamine receptor blockade in women with physiological or pathological hyperprolactinaemia

The TSH and PRL responses to administration of the two dopamine (DA) receptor antagonists sulpiride and domperidone, were studied in fifteen normoprolactinaemic subjects, twenty-two post-partum women and sixteen subjects with presumptive evidence of (six subjects) or surgically confirmed (ten subjects) prolactinomas. Sulpiride (100 mg i.m.) or domperidone (10 mg i.v.) elicited a slight increase in basal TSH levels in both normoprolactinaemic and post-partum women, but induced a clear-cut TSH rise in subjects with a tumour. Conversely, sulpiride and domperidone strikingly stimulated PRL secretion in normoprolactinaemic and post-partum women, but only slightly enhanced base-line PRL levels in women with prolactinomas. The reason for the reciprocal pattern of TSH and PRL responsiveness to DA receptor blockade of post-partum women and subjects with prolactinomas is presently obscure. Since baseline PRL levels in the two hyperprolactinaemic states overlapped widely, it would appear that hyperprolactinaemia per se is not responsible for such behaviour.

Impaired prolactin responsiveness to dopamine antagonists in acromegaly

Prolactin (PRL) and growth hormone (GH) secretion have been evaluated in 17 acromegalic patients following acute administration of two dopamine (DA) receptor antagonists, i.e. sulpiride (SULP) and domperidone (DOM). Six patients had persistent hyperprolactinemia. In 8 normoprolactinemic patients, i.m. injection of 100 mg SULP elicited only a slight rise iN plasma PRL, which was strikingly lower than that SULP induced in control subjects. Likewise, an i.v. bolus injection of DOM (4 mg) was barely effective to raise plasma PRL in the 11 normoprolactinemic and the 6 hyperprolactinemic patients. DOM was instead capable of inducing a clear-cut rise in plasma PRL in normoprolactinemic controls and in a group of subjects with puerperal hyperprolactinemia. Neither drug affected GH secretion in acromegalic patients. It is proposed that a defective tuberoinfundibular DA function or, alternatively, a diminished PRL reserve due to a decrease pituitary lactotroph mass may be responsible for the blunted PRL responsiveness of acromegalics. However, standing the paucity of present knowledge on the pituitary PRL secretory pool in acromegalics, neither hypothesis seems capable to account satisfactory for the reported results.

The risk of pronounced hyperkalaemia after arginine infusion in the diabetic subject

Following previous work showing that i.v. arginine induces a fall in blood phosphorus and an increase in blood potassium in normal subjects, investigation of the mechanism underlying these metabolic changes was extended to a group of 14 insulin-dependent diabetics and a further 6 normal volunteers. In the diabetics, arginine (0.5 g/kg body weight) in 30 min caused a slight, but significant fall in blood phosphorus (delta = -0.40 +/- 0.04 mg/ml p less than 0.01). This was well below the fall noted in the normal subjects, which, as demonstrated in the earlier study, is to a great extent mediated by insulin. The increase in blood potassium was much more marked than in the normal subjects (delta = + 1.42 +/- 0.15 mEq /l; p less than 0.001) and rose to pathological levels (5.6 to 6.5. mEg/l) in 9 out of 14 patients. There were no significant changes in blood pH, plasma osmolality, or plasma aldosterone. Inhibition of the glucagon response to arginine by means of a priming dose of 250 micrograms somatostatin, followed by infusion of 1,500 micrograms/hr, did not abolish the rise in blood potassium. These findings indicate that insulin protect against arginine-induced hyperkalaemia and that this metabolic alteration does not depend on glucagon, acidosis, enhance plasma osmolality, nor the suppression of aldosterone secretion. Persons with low insulin secretion due, for example, to stress or diabetes, run the risk of pathological hyperkalaemia if subjected to i.v. infusion of arginine.

Dicentric Y chromosome in a patient with gonadal dysgenesis and seminoma

A male patient with ambiguous external genitalia developed a seminoma in the left inguinal region; his internal genitalia included a streak gonad on the right and a small uterus. Cytogenetic studies demonstrated a dicentric Y chromosome with unstable behavior during cell division, which resulted in 45,X/46,X,dic(Y)/47,X,dic(Y),dic(Y) mosaicism. Immunogenetic studies allowed the identification of the male-determining H-Y antigen on both leukocytes and red cells of the patient. The significance of these results is discussed with respect to recent data on the genetic control of H-Y antigen.

Increased thyrotrophin and prolactin secretion induced by domperidone in hypothyroid subjects

The thyrotrophin (TSH) and prolactin (Prl) releasing effects of domperidone, a recently developed antidopaminergic drug which does not cross the blood-brain barrier, were investigated in 8 women affected by primary hypothyroidism, and were compared to those elicited by another antidopaminergic drug, sulpiride. Domperidone (4 mg iv) induced a clear-cut and sustained rise in both plasma TSH and Prl, with peak levels occurring 15 and 30 min post-injection, respectively. The increments in plasma Prl after domperidone were significantly higher than those in plasma TSH. The TSH and Prl responses induced by domperidone were almost superimposable to those provoked in the same subjects by sulpiride (100 mg im). In view of the inability of domperidone to penetrate into the central nervous system (CNS), these findings imply a 'peripheral' site(s) of action (i.e. anterior pituitary and/or median eminence) for the effect of antidopaminergic drugs on TSH secretion, and, re-iterate the notion that the same 'peripheral' sites are involved in the Prl-releasing effect of these compounds.

Tests of prolactin secretion in the diagnosis of hyperprolactinemic states: nomifensine and domperidone

Forty-one subjects with hyperprolactinemia underwent testing on separate occasions with nomifensine, an indirectly acting dopamine agonist, and domperidone, a dopamine receptor-blocking agent. Nomifensine (200 mg orally) did not significantly modify plasma levels of prolactin (PRL) in 17 subjects in whom the existence of a pituitary tumor had been established at surgery (12 subjects) or was highly probable (5 subjects). Of the remaining 24 patients with hyperprolactinemia of uncertain etiology, 6 had PRL responsiveness to nomifensine (decrease of baseline PRL levels greater than or equal to 30%) and 18 had PRL unresponsiveness to the drug. The administration of domperidone (4-mg bolus injected intravenously) showed in 36 of the 41 patients the existence of a homogeneity between PRL responsiveness to nomifensine and PRL responsiveness to domperidone. In only five patients was failure of nomifensine to lower plasma PRL levels associated with an increase in plasma PRL levels after domperidone administration (at least doubling of baseline PRL levels). The combined application of nomifensine and domperidone tests holds promise of being a useful method for distinguishing among hyperprolactinemic subjects those with a prolactinoma.

Partial remission of hyperprolactinemic amenorrhea after bromocriptine-induced pregnancy

Clinical and/or biological improvement has been observed in 7 out of 17 patients with hyperprolactinemic amenorrhea followed for 6-15 months after the successful outcome of bromocriptine (Parlodel, Sandoz)- induced pregnancy. The ovulatory cycle was resumed in 2 out of these 7 patients (with subsequent spontaneous conception in 1); in 3 others the medroxyprogesterone acetate test became positive. In all cases, post-partum prolactin values were considerably reduced. The possible causes of this improvement are discussed, examining the present data and those in the literature. Regressive lesions, due for example to vascularization defects or hemorrhage occurring in the prolactin-secreting tissue, as a result of the hyperplastic stimulus of estrogens during pregnancy, are suggested as a possible explanation.

Influence of glucagon on plasma levels of potassium in man

To investigate the role played by glucagon in the regulation of plasma potassium, we have examined the behaviour of this ion during four 2 h infusions of saline, glucagon (200 ng/min), cyclic somatostatin (priming dose of 50 microgram followed by 5.8 microgram/min) and somatostatin plus glucagon in 6 normal volunteers. Glucagon alone produced no change in potassium, despite an increase in insulin. Somatostatin, in addition to depressing insulin, produced a slight but significant (P < 0.01) increase in potassium (delta max: 0.2-0.8 mmol/1: mean +/- SEM, 0.4 +/- 0.1). Infusion of somatostatin together with glucagon suppressed the glucagon-induced increase in insulin and greatly augmented the increase in blood glucose. Potassium rose significantly more (P < 0.02) than after somatostatin alone (delta max: 0.5-1.3 mmol/l; mean 0.9 +/- 0.1), indicating that hyperkalaemia results from hyperglucagonaemia in the absence of insulin. Evidence is presented that this last phenomenon is not mediated by hyperglycaemia or by a reduction in aldosterone secretion. It is suggested that low blood insulin and increased glucagon could be one of the mechanisms that underlie or magnify the hyperkalaemia observed in cases of serious stress or decompensated diabetes.

Effect of sulpiride on plasma prolactin levels in women with puerperal or pathological hyperprolactinaemia

The effect of 100 mg im sulpiride on plasma Prl levels was studied in 10 normal females, 21 patients with galactorrhoea and normal plasma Prl, 10 women with puerperal hyperprolactinaemia and 27 patients with amenorrhoea-galactorrhoea and high plasma Prl levels. The response to sulpiride in patients with galactorrhoea but normal PRL was slightly higher (P < 0.05) than that observed in normal women, but only if expressed in per cent. Women with puerperal hyperprolactinaemia respond to the drug with a marked increase in Prl (mean +/- SEM: 563.0 +/- 142.8%), even though their baseline values are already very high (mean +/- SEM: 133.6 +/- 23.8 ng/ml). By contrast, there is a lower or no response to sulpiride in 13 women with pituitary tumour. The same was true in 11 patients with hyperprolactinaemia of uncertain aetiology but also 10 of these subjects presented signs suggestive of a tumour. In the last 3 patients with pathological hyperprolactinaemia in whom a consistent Prl increase after sulpiride was observed, hyperprolactinaemia was probably not of tumourous origin. On the basis of these results, the sulpiride test appears promising for discriminating between organic and 'functional' cases of enhanced Prl secretion.

Hormone patterns during bromocriptine-induced pregnancy in hyperprolactinemic patients

Plasma prolactin (PRL) and human placental lactogen (HPL), and urinary estriol and pregnanediol were studied during pregnancies induced with bromocriptine (Parlodel, Sandoz) in 10 cases of hyperprolactinemia. Previous selective adenomectomy or intrasellar implantation of radioactive gold (198Au) failed to induce a complete remission in 3 of these subjects. PRL rapidly increases after bromocriptine withdrawal, reaching values higher than those in normal women in the same stage of pregnancy within a few weeks. At term, pathological PRL levels occurred in 3 subjects only (with distinct alterations of the sella turcica). Estriol, pregnanediol and HPL were normal in all cases. These findings suggest that PRL levels higher than those normally observed during pregnancy do not alter fetoplacental endocrine function.