An Update on the COGiTATE Phase II Study: Feasibility and Safety of Targeting an Optimal Cerebral Perfusion Pressure as a Patient-Tailored Therapy in Severe Traumatic Brain Injury

INTRODUCTION

Monitoring of cerebral autoregulation (CA) in patients with a traumatic brain injury (TBI) can provide an individual 'optimal' cerebral perfusion pressure (CPP) target (CPPopt) at which CA is best preserved. This potentially offers an individualized precision medicine approach. Retrospective data suggest that deviation of CPP from CPPopt is associated with poor outcomes. We are prospectively assessing the feasibility and safety of this approach in the COGiTATE [CPPopt Guided Therapy: Assessment of Target Effectiveness] study. Its primary objective is to demonstrate the feasibility of individualizing CPP at CPPopt in TBI patients. The secondary objectives are to investigate the safety and physiological effects of this strategy.

METHODS

The COGiTATE study has included patients in four European hospitals in Cambridge, Leuven, Nijmegen, and Maastricht (coordinating centre). Patients with severe TBI requiring intracranial pressure (ICP)-directed therapy are allocated into one of two groups. In the intervention group, CPPopt is calculated using a published (modified) algorithm. In the control group, the CPP target recommended in the Brain Trauma Foundation guidelines (CPP 60-70 mmHg) is used.

RESULTS

Patient recruitment started in February 2018 and will continue until 60 patients have been studied. Fifty-one patients (85% of the intended total) have been recruited in October 2019. The first results are expected early 2021.

CONCLUSION

This prospective evaluation of the feasibility, safety and physiological implications of autoregulation-guided CPP management is providing evidence that will be useful in the design of a future phase III study in severe TBI patients.

Cerebrovascular Autoregulation Monitoring in the Management of Adult Severe Traumatic Brain Injury: A Delphi Consensus of Clinicians

BACKGROUND

Several methods have been proposed to measure cerebrovascular autoregulation (CA) in traumatic brain injury (TBI), but the lack of a gold standard and the absence of prospective clinical data on risks, impact on care and outcomes of implementation of CA-guided management lead to uncertainty.

AIM

To formulate statements using a Delphi consensus approach employing a group of expert clinicians, that reflect current knowledge of CA, aspects that can be implemented in TBI management and CA research priorities.

METHODS

A group of 25 international academic experts with clinical expertise in the management of adult severe TBI patients participated in this consensus process. Seventy-seven statements and multiple-choice questions were submitted to the group in two online surveys, followed by a face-to-face meeting and a third online survey. Participants received feedback on average scores and the rationale for resubmission or rephrasing of statements. Consensus on a statement was defined as agreement of more than 75% of participants.

RESULTS

Consensus amongst participants was achieved on the importance of CA status in adult severe TBI pathophysiology, the dynamic non-binary nature of CA impairment, its association with outcome and the inadvisability of employing universal and absolute cerebral perfusion pressure targets. Consensus could not be reached on the accuracy, reliability and validation of any current CA assessment method. There was also no consensus on how to implement CA information in clinical management protocols, reflecting insufficient clinical evidence.

CONCLUSION

The Delphi process resulted in 25 consensus statements addressing the pathophysiology of impaired CA, and its impact on cerebral perfusion pressure targets and outcome. A research agenda was proposed emphasizing the need for better validated CA assessment methods as well as the focused investigation of the application of CA-guided management in clinical care using prospective safety, feasibility and efficacy studies.

Non-invasive assessment of ICP in children: advances in ultrasound-based techniques

The assessment of intracranial pressure (ICP) in children with neurological disease remains a cornerstone in their routine management. The quest for a reliable, reproducible and radiation-free non-invasive technique for assessing ICP in children remains somewhat of a holy grail for neurosurgery. This work assesses some of the recent advances in ultrasound-based techniques, addressing both novel processes and modifications aimed at improving the accuracy of existing techniques.

Acute ischaemic stroke: challenges for the intensivist

PURPOSE

To provide an update about the rapidly developing changes in the critical care management of acute ischaemic stroke patients.

METHODS

A narrative review was conducted in five general areas of acute ischaemic stroke management: reperfusion strategies, anesthesia for endovascular thrombectomy, intensive care unit management, intracranial complications, and ethical considerations.

RESULTS

The introduction of effective reperfusion strategies, including IV thrombolysis and endovascular thrombectomy, has revolutionized the management of acute ischaemic stroke and transformed outcomes for patients. Acute therapeutic efforts are targeted to restoring blood flow to the ischaemic penumbra before irreversible tissue injury has occurred. To optimize patient outcomes, secondary insults, such as hypotension, hyperthermia, or hyperglycaemia, that can extend the penumbral area must also be prevented or corrected. The ICU management of acute ischaemic stroke patients, therefore, focuses on the optimization of systemic physiological homeostasis, management of intracranial complications, and neurological and haemodynamic monitoring after reperfusion therapies. Meticulous blood pressure management is of central importance in improving outcomes, particularly in patients that have undergone reperfusion therapies.

CONCLUSIONS

While consensus guidelines are available to guide clinical decision making after acute ischaemic stroke, there is limited high-quality evidence for many of the recommended interventions. However, a bundle of medical, endovascular, and surgical strategies, when applied in a timely and consistent manner, can improve long-term stroke outcomes.

Effects of pneumoperitoneum and Trendelenburg position on intracranial pressure assessed using different non-invasive methods

BACKGROUND

The laparoscopic approach is becoming increasingly frequent for many different surgical procedures. However, the combination of pneumoperitoneum and Trendelenburg positioning associated with this approach may increase the patient's risk for elevated intracranial pressure (ICP). Given that the gold standard for the measurement of ICP is invasive, little is known about the effect of these common procedures on ICP.

METHODS

We prospectively studied 40 patients without any history of cerebral disease who were undergoing laparoscopic procedures. Three different methods were used for non-invasive estimation of ICP: ultrasonography of the optic nerve sheath diameter (ONSD); transcranial Doppler-based (TCD) pulsatility index (ICP_PI); and a method based on the diastolic component of the TCD cerebral blood flow velocity (ICP_FVd). The ONSD and TCD were measured immediately after induction of general anaesthesia, after pneumoperitoneum insufflation, after Trendelenburg positioning, and again at the end of the procedure.

RESULTS

The ONSD, ICP_FVd, and ICP_PI increased significantly after the combination of pneumoperitoneum insufflation and Trendelenburg positioning. The ICP_FVd showed an area under the curve of 0.80 [95% confidence interval (CI) 0.70-0.90] to distinguish the stage associated with the application of pneumoperitoneum and Trendelenburg position; ONSD and ICP_PI showed an area under the curve of 0.75 (95% CI 0.65-0.86) and 0.70 (95% CI 0.58-0.81), respectively.

CONCLUSIONS

The concomitance of pneumoperitoneum and the Trendelenburg position can increase ICP as estimated with non-invasive methods. In high-risk patients undergoing laparoscopic procedures, non-invasive ICP monitoring through a combination of ONSD ultrasonography and TCD-derived ICP_FVd could be a valid option to assess the risk of increased ICP.

Non-invasive Monitoring of Intracranial Pressure Using Transcranial Doppler Ultrasonography: Is It Possible?

Although intracranial pressure (ICP) is essential to guide management of patients suffering from acute brain diseases, this signal is often neglected outside the neurocritical care environment. This is mainly attributed to the intrinsic risks of the available invasive techniques, which have prevented ICP monitoring in many conditions affecting the intracranial homeostasis, from mild traumatic brain injury to liver encephalopathy. In such scenario, methods for non-invasive monitoring of ICP (nICP) could improve clinical management of these conditions. A review of the literature was performed on PUBMED using the search keywords 'Transcranial Doppler non-invasive intracranial pressure.' Transcranial Doppler (TCD) is a technique primarily aimed at assessing the cerebrovascular dynamics through the cerebral blood flow velocity (FV). Its applicability for nICP assessment emerged from observation that some TCD-derived parameters change during increase of ICP, such as the shape of FV pulse waveform or pulsatility index. Methods were grouped as: based on TCD pulsatility index; aimed at non-invasive estimation of cerebral perfusion pressure and model-based methods. Published studies present with different accuracies, with prediction abilities (AUCs) for detection of ICP ≥20 mmHg ranging from 0.62 to 0.92. This discrepancy could result from inconsistent assessment measures and application in different conditions, from traumatic brain injury to hydrocephalus and stroke. Most of the reports stress a potential advantage of TCD as it provides the possibility to monitor changes of ICP in time. Overall accuracy for TCD-based methods ranges around ±12 mmHg, with a great potential of tracing dynamical changes of ICP in time, particularly those of vasogenic nature.

Non-invasive assessment of intracranial pressure

Monitoring of intracranial pressure (ICP) is invaluable in the management of neurosurgical and neurological critically ill patients. Invasive measurement of ventricular or parenchymal pressure is considered the gold standard for accurate measurement of ICP but is not always possible due to certain risks. Therefore, the availability of accurate methods to non-invasively estimate ICP has the potential to improve the management of these vulnerable patients. This review provides a comparative description of different methods for non-invasive ICP measurement. Current methods are based on changes associated with increased ICP, both morphological (assessed with magnetic resonance, computed tomography, ultrasound, and fundoscopy) and physiological (assessed with transcranial and ophthalmic Doppler, tympanometry, near-infrared spectroscopy, electroencephalography, visual-evoked potentials, and otoacoustic emissions assessment). At present, none of the non-invasive techniques alone seem suitable as a substitute for invasive monitoring. However, following the present analysis and considerations upon each technique, we propose a possible flowchart based on the combination of non-invasive techniques including those characterizing morphologic changes (e.g., repetitive US measurements of ONSD) and those characterizing physiological changes (e.g., continuous TCD). Such an integrated approach, which still needs to be validated in clinical practice, could aid in deciding whether to place an invasive monitor, or how to titrate therapy when invasive ICP measurement is contraindicated or unavailable.

Intraoperative non invasive intracranial pressure monitoring during pneumoperitoneum: a case report and a review of the published cases and case report series

Non-invasive measurement of ICP (nICP) can be warranted in patients at risk for developing increased ICP during pneumoperitoneum (PP). Our aim was to assess available data on the application of nICP monitoring during these procedures and to present a patient assessed with an innovative combination of noninvasive tools. Literature review of nICP assessment during PP did not find any studies comparing different methods intraprocedurally and only few studies of any nICP monitoring were available: transcranial Doppler (TCD) studies used the pulsatility index (PI) as an estimator of ICP and failed to detect a significant ICP increase during PP, whereas two out of three optic nerve sheath diameter (ONSD) studies detected a statistically significant ICP increase. In the case study, we describe a 52 year old man with a high grade thalamic glioma who underwent urgent laparoscopic cholecystectomy. Considering the high intraoperative risk of developing intracranial hypertension, he was monitored through parallel ONSD ultrasound measurement and TCD derived formulae (flow velocity diastolic formula, FVdnICP, and PI). ONSD and FVdnICP methods indicated a significant ICP increase during PP, whereas PI was not significantly increased. Our experience, combined with the literature review, seems to suggest that PI might not detect ICP changes in this context, however we indicate a possible interest of nICP monitoring during PP by means of ONSD and of TCD derived FVdNICP, especially for patients at risk for increased ICP.

Respiratory failure due to upper airway obstruction in children: use of the helmet as bridge interface

Upper airway obstruction (UAO) can cause severe respiratory distress in young children by increasing inspiratory muscle load and decreasing alveolar ventilation, ultimately resulting in hypercapnia and hypoxemia which have long term negative cardiovascular effects. Although non-invasive continuous positive airway pressure (CPAP) improves gas exchange in these patients, use of conventional interfaces (nasal mask, nasal pillow and facial mask) may cause significant discomfort and lead to CPAP intolerance. We report five cases of children affected by UAO who experienced CPAP intolerance via application of conventional interfaces. Alternatively, we acutely applied helmet-CPAP which resulted in improved breathing pattern and gas exchange. Thereafter, patients received training with respect to a nasal CPAP interface, allowing successful long term treatment. In conclusion, these five clinical cases demonstrate that helmet-CPAP can be used acutely in children with UAO if compliance to conventional modalities is problematic, allowing for sufficient time to achieve compliance to nasal-CPAP.

Clinical outcome of adjuvant endocrine treatment according to PR and HER-2 status in early breast cancer

Patients with estrogen receptor (ER)+/progesterone receptor (PR)- and/or HER-2 overexpressing breast carcinomas may derive lower benefit from endocrine treatment. We examined retrospectively data from 972 breast cancer patients who received tamoxifen (725), tamoxifen + Gn-RH analogs (127) and aromatase inhibitors (120) as adjuvant treatments. ER+/PR- versus ER+/PR+ tumours were characterised by larger size (P = 0.001), higher tumour grade (P = 0.001), higher Ki-67 expression (P = 0.001) and lower mean ER (P = 0.000) and HER-2 expression (P = 0.000). At univariate analysis, tumour grading [hazard ratio (HR) = 4.0; 95% confidence interval (CI) = 1.4-11.1; P = 0.007], nodal status (HR = 3.4; 95% CI 1.2-5.7; P = 0.000), tumour diameter (HR = 2.9; 95% CI 1.7-4.7; P = 0.000) lack of PR expression (HR = 2.1; 95% CI 1.3-3.4; P = 0.002) and HER-2 overexpression (HR = 1.9; 95% CI 1.0-3.5; P = 0.03), as well as Ki 67 expression (HR = 1.7; 95% CI 1.0-2.7; P = 0.04) were associated with shorter disease-free survival (DFS). At the multivariate analysis, nodal status (HR = 3.6; 95% CI 1.9-6.8; P = 0.0001), lack of PR expression (HR = 2.3; 95% CI 1.3-4.0; P = 0.003) and tumour diameter (HR = 2.1; 95% CI 1.1-3.8; P = 0.018) retained their prognostic significance, whereas HER-2 overexpression was associated with a trend towards shorter DFS that was of borderline statistical significance (HR = 2.0; 95 % CI 1.0-3.9; P = 0.05). Our data suggest that lack of PR expression and HER-2 overexpression are both associated with aggressive tumour features, but the prognostic information of PR status on the risk of recurrence in endocrine-treated breast cancer patients is stronger.

Erythrocyte Na+,K+,Cl- cotransport and kidney function in essential hypertension

OBJECTIVE

To determine whether essential hypertensive patients with high Na+,K+,Cl- cotransport (COT) display alterations of some indices of kidney tubular reabsorption similar to those observed in Milan hypertensive (MHS) rats, which have high COT in both erythrocytes and kidney tubular cells, and hypertension caused by a primary increase of tubular reabsorption.

DESIGN

Two sets of experiments were performed. First, renal function in two subgroups of hypertensive patients (one with 'high' and one with 'normal' COT was compared with that in normotensive controls. Secondly, the natriuretic and diuretic effects of a single oral dose of frusemide (25 mg) were analysed in six high- and in six normal- COT hypertensive patients.

RESULTS

Compared with normotensives and with normal-COT hypertensives, high-COT hypertensives had lower fractional uric acid excretion and plasma renin activity with similar glomerular filtration rate and urinary sodium and potassium excretion. COT was negatively correlated with fractional uric acid excretion in the essential hypertensive patients but not in the normotensives. The diuretic natriuretic response to frusemide was much higher in high- than in normal-COT hypertensives.

CONCLUSION

These results are consistent with the hypothesis that patients with high COT have abnormal renal handling of sodium similar to that observed in MHS rats.

Genetics of renal damage in primary hypertension

Little is known of the genetics of glomerular damage in essential hypertension in humans. The prevalence of end-stage renal disease due to primary hypertension varies from 20% to 30% of all cases of renal failure to as low as 0.002%. This depends not only on differences in diagnostic criteria but also on different racial susceptibility to the disease as well as on different genetic backgrounds in different subsets of individuals of the same race. A review of the literature is provided, together with an example of how a point mutation that causes hypertension in Milan hypertensive rats can provide a model to analyze this issue correctly.

Long-term trophic effect of sodium restriction on the rat adrenal zona glomerulosa. I. Its partial independence of the renin-angiotensin system

The mechanism of the trophic effect of chronic sodium restriction on the zona glomerulosa of the rat adrenals was investigated by combined morphometric and biochemical techniques. In the normal rats, prolonged sodium deprivation caused a significant hypertrophy of the zona glomerulosa and its parenchymal cells, coupled with a conspicuous rise in the plasma concentration of aldosterone. Analogous results were observed in animals simultaneously administered captopril and maintenance doses of angiotensin II. However, in this last case, the changes were significantly lower than those observed in the normal rats. These findings are compatible with the view that the activation of the renin-angiotensin system is not the sole mechanism involved in the stimulation of the growth and steroidogenic capacity of rat adrenal zona glomerulosa induced by chronic sodium restriction.

Long-term trophic effect of sodium restriction on the rat adrenal zona glomerulosa. II. The possible involvement of the inhibition of the dopaminergic system

The effects of chronic administration of metoclopramide or bromocriptine (two drugs which act as antagonist and agonist of dopamine receptors) on the zona glomerulosa of captopril-treated rats administered maintenance doses of angiotensin II, were investigated by combined morphometric and biochemical techniques. It was found that metoclopramide provoked a significant hypertrophy of the zona glomerulosa and its parenchymal cells, coupled with a persistent rise in the plasma concentration of aldosterone, only in rats fed a normal diet. Conversely, bromocriptine exerted an evident inhibitory effect on the zona glomerulosa growth and steroidogenic capacity only in chronically sodium-deprived animals. These findings strongly suggest that sodium balance modulates the activity of the dopaminergic system, whose chronic suppression may be involved in the mechanism underlying the extra-angiotensin adrenoglomerulotrophic effect of prolonged sodium restriction.

Effects of prolonged treatment with cyanoketone on the zona fasciculata of rat adrenal cortex. A combined morphometric and biochemical study

The effects of a 7-day administration of cyanoketone (CKT) on the adrenal zona fasciculata were examined in "normal" and dexamethasone/ACTH-infused rats. The drug caused a 48-56% decrease in the blood concentration of corticosterone, coupled with a 53-58% lowering in the activity of 3 beta-hydroxysteroid dehydrogenase (3 beta HSD), in both groups of animals. In the "normal" rats, CKT induced a significant hypertrophy of the zona fasciculata and its parenchymal cells, due to an increase in volume of the mitochondrial compartment and to proliferation of the smooth endoplasmic reticulum (SER), as well as a notable rise in both the volume of the lipid-droplet compartment and the intracellular concentration of total cholesterol. The activity of 11 beta-hydroxylase was conspicuously enhanced. All these responses of zona fasciculata cells to CKT did not occur in dexamethasone/ACTH-treated animals, and therefore they were considered to be non-specific and mediated by the augmented secretion of ACTH following lowering of the corticosterone level in the blood. In the dexamethasone/ACTH-infused rats, the only morphological change induced by CKT was a significant decrease in the surface area per cell and surface density of the SER, which was interpreted as the morphological counterpart (not masked by the increased level of circulating ACTH) of the drug-induced inhibition of the microsomal 3 beta HSD.

Effects of ACTH and aminoglutethimide administration on the morphological and functional responses of rat adrenal zona fasciculata to a prolonged treatment with 4-aminopyrazolo-pyrimidine

The prolonged administration of the hypocholesterolaemic drug 4-APP induced morphological changes in rat zona fasciculata cells (AER hypertrophy, peroxisome proliferation and lipid droplet depletion), enabling them to synthesise their own cholesterol and to maintain an adequate level of corticosterone output. Chronic ACTH administration provoked, in zona fasciculata cells of 4-APP-treated rats, a further increase in the AER and the volume of peroxisome compartment, coupled with a significant rise in the volume of the mitochondrial compartment and in the surface area per cell of mitochondrial cristae; the volume of the lipid droplet compartment did not change, whereas the plasma level of corticosterone significantly increased. These findings indicate that the modified adrenocortical cells of 4-APP-treated rats possess a good functional reserve, being still able to enhance their growth and steroidogenic capacity in response to ACTH. Aminoglutethimide, a drug blocking cholesterol utilisation in steroid synthesis, lowered the blood level of corticosterone in 4-APP/ACTH-administered rats; it increased the intra-adrenal concentration of cholesterol, but did not provoke lipid droplet accumulation in zona fasciculata cells. This result may suggest that in adrenal lipid droplets is stored only exogenous cholesterol taken up from plasma lipoproteins.

Investigations on the possible involvement of the dopaminergic system in the modulation of the growth and steroidogenic capacity of the rat adrenal zona glomerulosa: a coupled morphometric and biochemical study

The effects of metoclopramide (MTC) and bromocriptine (BRC) (two drugs which act as antagonist and agonist of DOPA-receptors, respectively) on the zona glomerulosa of dexamethasone/ACTH-treated rats were investigated by coupled biochemical and morphometric techniques. Short-term (1-h) MTC administration significantly increased the plasma concentration of aldosterone, while long-term (7-day) MTC administration, as well as short- and long-term treatment with BRC did not cause any apparent change. Long-term MTC administration was found to significantly potentiate both the rise in the plasma level of aldosterone and the hypertrophy of the zona glomerulosa and its parenchymal cells induced by a prolonged treatment with angiotensin II (AII), but not those evoked by a chronic sodium deprivation alone or combined with AII infusion. Long-term BRC administration notably counteracted the effects of sodium restriction (coupled or not with AII infusion), but not those induced by the administration of AII alone. Long-term MTC administration partially reversed both the lowering of the plasma concentration of aldosterone and the atrophy of the zona glomerulosa and its parenchymal cells caused by a prolonged sodium-loading (combined or not with captopril infusion), but not those produced by the administration of captopril alone. On the other hand, long-term BRC treatment induced a further significant reduction in the blood level of aldosterone and the volume of zona glomerulosa and its cells only in captopril-treated animals. These findings are consistent with the view that the dopaminergic system exerts a maximal tonic inhibitory effect not only on the secretory activity, but also on the growth and steroidogenic capacity of the rat zona glomerulosa. Furthermore, they suggest that the activity of the dopaminergic system is in turn controlled by the sodium balance, being almost completely suppressed by a prolonged sodium deprivation.

Effects of a prolonged treatment with aminoglutethimide on the zona fasciculata of rat adrenal cortex: a morphometric investigation

The effects of a 7-day administration of aminoglutethimide (AG) on the adrenal zona fasciculata were examined in "normal" and dexamethasone/ACTH-treated rats. There was a 70-74% decrease in the concentration of corticosterone in blood, but no conspicuous qualitative changes suggesting cell degeneration occurred. Morphometry showed that AG induced a significant hypertrophy of the zona fasciculata and its parenchymal cells only in "normal" animals, which was due to an increase in the volume of the mitochondrial compartment and to proliferation of the smooth endoplasmic reticulum. This response to AG was considered to be non-specific and mediated by the enhanced secretion of ACTH following the decrease in the blood level of corticosterone. AG administration significantly increased the volume of the lipid-droplet compartment and the number of intramitochondrial lipid-like inclusions in both groups of animals. These changes were interpreted as the morphological counterpart of the AG-induced block of cholesterol utilization in steroid synthesis.

Long-term trophic action of alpha-melanocyte-stimulating hormone on the zona glomerulosa of dexamethasone -or captopril-treated rats, with or without maintenance doses of ACTH or angiotensin. II: Stereology and plasma hormone concentrations

The effects of a long-term (7 days) administration of alpha-melanocyte-stimulating hormone (alpha-MSH) on the zona glomerulosa were investigated in "normal" rats and in animals in which the hypothalamic-hypophyseal-adrenal axis and the renin-angiotensin system had been pharmacologically interrupted. alpha-MSH caused a notable hypertrophy of the zona glomerulosa and its parenchymal cells, as well as a significant increase in the plasma concentration of aldosterone, in rats infused with dexamethasone, dexamethasone plus ACTH or captopril plus angiotensin II, but not in animals treated with captopril alone. These findings indicate that alpha-MSH is directly involved in the stimulation of the growth and steroidogenic capacity of rat zona glomerulosa, and that this action of alpha-MSH requires a normal level of circulating angiotensin II.

Short- and long-term effects of angiotensin II on the rat adrenal zona glomerulosa. A coupled stereological and enzymological study

Long-term angiotensin II administration induced a time-dependent increase in the volume of rat zona glomerulosa cells and in the plasma concentration of aldosterone. Cell hypertrophy is coupled with comparable increases in the surface area per cell of mitochondrial cristae and in the activity per cell of 18-hydroxylase. 11 beta-hydroxylase activity was not affected. These findings allow to suggest that the angiotensin-II-enhanced growth of rat zona glomerulosa is associated with the de novo synthesis of 18-hydroxylase.

Long term effects of the hypocholesterolaemic drug 4-aminopyrazolo-pyrimidine on the zona fasciculata of the rat adrenal cortex

Prolonged 4-APP administration to dexamethasone/ACTH-treated rats was found to lower both plasma and intra-adrenal gland cholesterol concentrations. Morphological examination showed that zona fasciculata cells underwent a severe lipid droplet depletion, and a conspicuous increase of agranular endoplasmic reticulum and peroxisomes. The blood level of corticosterone remained unchanged. A high cholesterol diet completely reversed the effects of 4-APP treatment. The hypothesis is discussed that these morphological changes are the expression of a compensatory response enabling rat adrenocortical cells to maintain an adequate level of hormone output even in the absence of a normal supply of exogenous cholesterol.

Investigations on the effects of long-term administration of a methionine-enkephalin analogue on the adrenal zona fasciculata of rats treated with dexamethasone or dexamethasone and ACTH

Prolonged (7 days) methionine-enkephalin (DALA) treatment provoked a dose-dependent increase in the volume of zona fasciculata cells of dexamethasone-administered rats, along with a notable rise in the plasma concentration of corticosterone and the activity of 11 beta-hydroxylase. Comparable dose-dependent effects were observed after chronic administration of ACTH to dexamethasone-suppressed rats. The chronic administration of the maximum dose of DALA (500 micrograms/kg/day) was found to significantly further the trophic action of ACTH on the zona fasciculata of dexamethasone-treated animals. It is suggested that enkephalins act independently of and synergistically with ACTH in stimulating the growth and steroidogenic capacity of the rat adrenal zona fasciculata.

Further studies on the effects of prolonged prolactin administration on the zona glomerulosa of the rat adrenal cortex

The effects of a prolonged treatment with prolactin on the morphology and hormone secretion of adrenal zona glomerulosa of gonadectomized testosterone-replaced rats were investigated by coupled morphometric and radioimmunologic techniques. The dexamethasone/captopril-induced atrophy of zona glomerulosa cells (-42%) and fall in the blood level of aldosterone (-37%) were partially counteracted by chronic prolactin administration: the values had increased by about 15% and 17%, respectively, but remained lower than in the control animals. The prolonged treatment with prolactin of dexamethasone/captopril-administered ACTH/angiotensin II-replaced rats provoked a striking increase in the zona glomerulosa cell volume (24%) and in the blood level of aldosterone (33%) above the control values. The possibility is discussed whether prolactin may be directly involved in the stimulation of the growth and steroidogenic capacity of rat zona glomerulosa, without interacting with the gonads and interfering with the hypothalamo-hypophyseal axis and the renin-angiotensin system.

Long-term trophic action of alpha-melanocyte-stimulating hormone on the zona glomerulosa of the rat adrenal cortex

The effects of alpha-melanocyte-stimulating hormone (alpha-MSH) on the rat adrenal cortex were investigated by coupled morphometric and radioimmunological techniques. Short-term alpha-MSH administration provoked a significant increase in the aldosterone plasma level along with a notable lipid droplet depletion in zona glomerulosa cells. Long-term alpha-MSH treatment induced a notable hypertrophy of zona glomerulosa cells and a further rise in the blood concentration of aldosterone. alpha-MSH did not affect zona fasciculata morphology and corticosterone plasma level. The possibility is discussed that alpha-MSH may be specifically involved in the control of the growth and steroidogenic capacity of rat adrenal zona glomerulosa.

Effects of chronic administration of a methionine-enkephalin analogue on the zona glomerulosa of the rat adrenal cortex

The effects of D-ala2-met-enkephalinamide (DALA) on the zona glomerulosa of dexamethasone-ACTH-treated rats were investigated by coupled radioimmunologic and morphometric techniques. Short-term DALA administration provoked a significant increase in the aldosterone plasma level along with a notable lipid droplet depletion in zona glomerulosa cells. Long-term DALA treatment induced a striking hypertrophy of zona glomerulosa cells and a further rise in the blood concentration of aldosterone. These findings seem to indicate that DALA is involved not only in the acute enhancement of aldosterone output but also in the stimulation of the growth and steroidogenic capacity of rat adrenal zona glomerulosa.

Sex differences in adrenocortical structure and function. XXII. Light- and electron-microscopic morphometric studies on the effects of gonadectomy and gonadal hormone replacement on the rat adrenal cortex

The cytological aspects of sexual dimorphism in the rat adrenal cortex and its relationship to the gonads have been investigated. The adrenal glands of mature female rats were heavier than those of males, and morphometry showed that this was almost exclusively due to conspicuous differences in the volume of cells of the zona fasciculata (ZF) and zona reticularis (ZR). Stereology demonstrated that the volume of the mitochondrial and lipid droplet compartments, as well as the surface area per cell of mitochondrial cristae and smooth endoplasmic reticulum tubules, were markedly higher in the ZF and ZR cells of female animals. Orchiectomy increased and ovariectomy decreased the adrenal weight, by eliciting hypertrophy and atrophy, respectively, of ZF and ZR cells; these effects of gonadectomy were reversed by the appropriate gonadal hormone replacement. It is suggested that the sexual dimorphism of the rat adrenal cortex may depend upon the inhibitory action of testosterone and the stimulatory effect of estradiol on the hypothalamo-hypophyseal-adrenal axis.

Evidence that long-term methionine-enkephalin administration stimulates rat adrenal zona fasciculata

Short-term methionine-enkephalin (DALA) treatment did not induce evident changes in the adrenal zona fasciculata and in the basal corticosterone output of dexamethasone-treated rats administered with maintenance doses of ACTH. Conversely, prolonged (5 days) DALA treatment caused a notable hypertrophy of zona fasciculata cells, along with a significant increase in the plasma concentration of corticosterone. It is suggested that enkephalins exert a trophic action on the rat zona fasciculata.

Short- and long-term effects of ACTH on the adrenal zona glomerulosa of the rat. A coupled stereological and enzymological study

Short-term ACTH treatment provoked a decrease in volume of the lipid-droplet compartment in rat zona glomerulosa cells, and a rise in plasma and intracellular concentrations of corticosterone and aldosterone. It enhanced activities of 3 beta-hydroxysteroid dehydrogenase (3 beta HSD), 11 beta-hydroxylase (11 beta OH) and 18-hydroxylase (18OH). Long-term ACTH administration produced a hypertrophy of the zona glomerulosa and its parenchymal cells, a result of the increase in volume of the smooth endoplasmic reticulum and the mitochondrial compartment. The surface area per cell of mitochondrial inner membranes increased; the tubular cristae were transformed into a homogeneous population of vesicles. The plasma and intracellular concentrations of corticosterone further increased, whereas those of aldosterone fell below basal levels (the "aldosterone-escape" phenomenon). The activities of 3 beta HSD and 11 beta OH were enhanced, that of 180H decreased. Therefore, ACTH stimulates zona glomerulosa growth and transforms parenchymal elements into zona fasciculata cell-types. Cyanoketone nullified acute ACTH effects on plasma and intracellular concentrations of corticosterone and aldosterone, but did not affect the activities of 11 beta OH and 18OH. Chronic ACTH treatment produced similar results, although 18OH activity was not suppressed. The mechanism underlying the "aldosterone-escape" phenomenon may thus involve a rise in the intracellular concentration of corticosterone, caused by the enhanced synthesis and activation of 3 beta HSD and 11 beta OH.

Effects of prolactin administration on the zona glomerulosa of the rat adrenal cortex: stereology and plasma hormone concentrations

The effects of short and prolonged treatments with prolactin on the morphology and hormone secretion of the rat adrenal zona glomerulosa were investigated by coupled morphometric and radioimmunological techniques. Short-term prolactin administration did not alter plasma aldosterone concentration or zona glomerulosa morphology. Conversely, chronic prolactin treatment caused both a notable hypertrophy of zona glomerulosa cells and a significant rise in the blood level of aldosterone. The possibility is discussed that prolactin may be involved in the control of the growth and steroidogenic capacity of the rat adrenal zona glomerulosa.

Further studies on the inhibitory effects of somatostatin on the growth and steroidogenic capacity of rat adrenal zona glomerulosa

Chronic somatostatin administration was found to partially reverse the ACTH-enhanced growth of the rat zona glomerulosa. The effect of somatostatin was completely superposable to that of captopril, a specific inhibitor of the angiotensin-converting enzyme, and the inhibitory actions of these two agents did not cumulate. Neither somatostatin nor captopril counteracted the ACTH-induced stimulation of the growth and steroidogenic capacity of the rat zona fasciculata. These findings support the view that somatostatin acts as an exclusive and specific modulator of the adrenoglomerulotrophic action of the renin-angiotensin system.

The possible potassium involvement in the modulation of the long-term trophic action of ACTH on the rat adrenal zona fasciculata

The effects of chronic potassium loading on the zona fasciculata of the rat adrenal cortex were investigated. It was found that potassium stimulates the growth and the steroidogenic capacity of the zona fasciculata presumably by enhancing the trophic effects of ACTH.

Effect of somatostatin on the zona glomerulosa of rats treated with angiotensin II or captopril: stereology and plasma hormone concentrations

Chronic somatostatin (SRIF) administration induced atrophy of zona glomerulosa cells of the rat adrenal cortex and a noticeable fall in the plasma concentration of aldosterone. The effects of SRIF were comparable with those of captopril, a specific inhibitor of the angiotensin-converting enzyme. SRIF completely abrogated the adrenoglomerulotrophic effects of angiotensin II (AII); the inhibitory actions of SRIF and captopril were not additive. The slight but significant enhancement of zona fasciculata cell growth and plasma corticosterone levels caused by chronic AII administration were ot reversed by SRIF. We interpret these data to indicate that SRIF specifically modulates the stimulatory effects of AII on the growth and steroidogenic capacity of rat zona glomerulosa.

Opposed effects of chronic prolactin administration on the zona fasciculata and zona reticularis of the rat adrenal cortex: an ultrastructural stereological study

The effects of a prolonged treatment with prolactin on the morphology and hormone secretion of rat adrenal zona fasciculata and zona reticularis, were investigated by coupled morphometric and radio-immunological techniques. Chronic prolactin administration provoked a notable atrophy of zona fasciculata cells and a small but significant increase in the corticosterone plasma level, which can be the result of the prolactin-induced inhibition of the intra-adrenal 5 alpha-reductase. Therefore, the atrophy of the zona fasciculata may be reasonably supposed to be not a direct effect of prolactin, but indirectly caused by a negative feed-back mechanism blocking ACTH release. On the contrary, prolonged prolactin treatment induced a conspicuous hypertrophy of zona reticularis cells, as well as a notable rise in the plasma concentration of testosterone, which cannot be due to gonad stimulation by prolactin since orchiectomized rats were employed. As the zona reticularis, like zona fasciculata, is ACTH-dependent, it must be concluded that prolactin exerts a direct stimulating effect on the growth of the zona reticularis, whose functional counterpart conceivably is an enhanced production of androgen hormones.

Trophic effects of potassium loading on the rat zona glomerulosa: permissive role of ACTH and angiotensin II

The trophic effects of chronic potassium loading on the rat zona glomerulosa were investigated by morphometric and radioimmunological methods. Potassium loading exerted a potent adrenoglomerulotrophic effect in saline treated control rats, but it was not able to reverse the captopril- and dexamethasone-induced atrophy of the zona glomerulosa. However, if the captopril/dexamethasone administered rats were given maintenance doses of angiotensin II and ACTH, potassium loading was found to exert a strong trophic action. The hypothesis is advanced that potassium loading requires the integrity of both the renin-angiotensin system and the hypothalamo-hypophyseal axis to exert its powerful direct stimulating effect on the growth and steroidogenic capacity of the rat zona glomerulosa.

Inhibitory effect of somatostatin on the growth and steroidogenic capacity of rat adrenal zona glomerulosa

Chronic administration of somatostatin induced atrophy of zona glomerulosa cells of rat adrenals and lowering of plasma aldosterone concentration. Zona fasciculata cells did not display any significant change and corticosterone plasma concentration was not significantly affected. These findings are interpreted to indicate that somatostatin exerts a direct inhibitory effect on the growth and steroidogenic capacity of rat adrenal zona glomerulosa.

Effects of ACTH on adrenocortical cells autotransplanted in the rat spleen: ultrastructural and morphometric observations

The effects of chronic ACTH administration on adrenocortical cells autotransplanted in the rat spleen have been investigated. Morphometry showed that ACTH induced a significant hypertrophy of adrenocortical cells, which was mainly due to the increase in the smooth endoplasmic reticulum and mitochondrial compartment. Competitive protein binding assay demonstrated that adrenocortical cell hypertrophy was associated with a two-fold rise in the plasma corticosterone concentration. These data indicate that autotransplanted adrenocortical cells are normally sensitive to ACTH, which enhances their growth and steroidogenic capacity.

Morphometric investigations into the mechanism of the compensatory hypertrophy of the rat adrenal zona fasciculata after unilateral adrenalectomy

Compensatory hypertrophy of the remaining gland in unilaterally adrenalectomized rats was investigated by morphometric techniques. It was observed that compensatory adrenal growth occurred in both dexamethasone-treated and hypophysectomized rats, receiving maintenance doses of ACTH. However, it was only half that found in intact animals. These results support the view that activation of the hypothalamo-hypophyseal axis is not the unique mechanism underlying adrenal compensatory hypertrophy in the rat.

Effects of testosterone on the zona fasciculata of the male rat adrenal cortex. A correlated stereological and biochemical study

The effects of long-term testosterone administration on the adrenal cortex of male rats were investigated by coupled morphometric and biochemical methods. Morphometry showed that testosterone treatment provoked a time-dependent atrophy of the zona fasciculata cells, which was mainly due to the decrease in the volume of the mitochondrial compartment and smooth endoplasmic reticulum (SER). Biochemical assays demonstrated that the decrease in the surface area per cell of SER membranes and mitochondrial cristae was tightly paralleled by the decrease in the activity per cell of two key enzymes of steroid synthesis contained in them (delta 5-3 beta-hydroxysteroid dehydrogenase and 11 beta-hydroxylase). The testosterone-induced inhibition of the growth maintenance and steroidogenic capacity of adrenocortical cells provoked a significant fall in the plasma concentration of corticosterone and a consequential increase in the level of circulating ACTH. Chronic administration of testosterone caused a notable suppression of the activity of the adrenal 5 alpha-reductase and this in turn provoked a rise in the intracellular concentration of corticosterone. Moreover, testosterone inhibited the incorporation of 3H-uridine into the nuclear and mitochondrial fractions of male rat adrenocortical cells. These findings exclude the possibility that the testosterone-provoked atrophy of the male rat adrenal glands is mediated by the suppression of the hypothalamo-hypophyseal axis, and suggest that the mechanism underlying this action of testosterone involves inhibition of nuclear and mitochondrial RNA synthesis. Whether this effect of testosterone is directly or indirectly mediated by the rise in the intracellular content of corticosterone due to the inhibition of 5 alpha-reductase activity, remains to be elucidated.

Effects of the hypolipidemic drug nafenopin on the zona fasciculata of the rat adrenal cortex: a correlated biochemical and stereological study

The effects of Nafenopin, a hypolipidemic drug, on the zona fasciculata of the rat adrenal cortex were investigated by biochemical, stereological, and cytochemical methods. Chronic Nafenopin treatment (5 days) significantly lowered serum cholesterol level, while it did not alter blood corticosterone concentration and 11beta-hydroxylase activity of adrenocortical cells. Stereology showed a significant increase in the average volume of zona fasciculata cells, which was almost exclusively due to smooth endoplasmic reticulum (SER) proliferation. The volume of lipid compartment was significantly reduced, whereas the volume of diaminobenzidine (DAB)-positive bodies (peroxisomes) per cell displayed a marked increase. Cholesterol administration per os to the treated animals raised the serum cholesterol level and completely reversed the Nafenopin effects. One day of Nafenopin administration provoked a slight but significant lipid depletion in adrenocortical cells, while 3 days of continuous drug treatment induced an extreme lipid depletion and a moderate increase in the SER coupled with a significant decrease in the plasma concentration of corticosterone. Since microsomal fraction and catalase seem to be involved in the cholesterol metabolism and utilization, the hypothesis is advanced that the Nafenopin-elicited SER and peroxisome proliferation is a compensatory response enabling adrenocortical cells to maintain an adequate level of hormonal output.

Ultrastructural observations on the regeneration of adrenocortical autotransplants in the rat spleen

The regeneration of adrenocortical autotransplants in the rat spleen has been investigated by light and electron microscopy. Up to the seventh day after implantation, adrenal grafts showed large areas of necrosis and contained many degenerating (apoptotic) adrenocortical cells, some mesenchyme-like poorly differentiated elements, and occasional viable parenchymal cells. These last cells possessed mitochondria with scanty tubular cristae and few profiles of smooth endoplasmic reticulum. After 15 days of regeneration, adrenal grafts were reduced in volume, but contained only viable adrenocortical cells; after 30-36 days, autotransplants were noticeably enlarged and surrounded by an evident connective tissue capsule. Regeneration was closely associated with the morphological differentiation of adrenocortical cells, which one month after transplantation were found to assume all the typical features of adult rat zona fasciculata elements (i.e. mitochondria with vesicular cristae, abundant smooth endoplasmic reticulum, some lipid droplets and a well developed Golgi apparatus).

An electron-microscopic stereological study of the compensatory hypertrophy of the rat adrenal zona fasciculata after unilateral adrenalectomy

The ultrastructural changes associated with the compensatory hypertrophy of the zona fasciculata cells on monoadrenalectomized rats were investigated by stereological techniques. It was found that these subcellular changes display a different pattern from those underlying the ACTH-induced adrenocortical cell growth in the intact rats. This result supports the view that compensatory adrenal hypertrophy does not involve activation of the hypothalamo-hypophyseal-adrenal axis.

Effects of a chronic treatment with testosterone on the morphology of the interstitial cells of the rat testis: an ultrastructural stereologic study

The suppressive effects of chronic testosterone administration on the rat testicular interstitial cells (Leydig cells) were investigated by stereological methods. The volume of cells, nuclei, mitochondrial compartment and smooth endoplasmic reticulum (SER), as well as the surface area of SER and mitochondrial cristae decreased significantly as a function of the duration of treatment. The decrease in the SER volume accounted for about 75-80% of that in the cell volume. These findings lend support to the view that SER is the subcellular organelle more responsive to the changes in the functional activity of rat Leydig cells.

Effects of sodium repletion and timolol maleate administration on the zona glomerulosa of the rat adrenal cortex: an electron microscopic morphometric study

The effects of long-term sodium repletion and timolol maleate treatment on the zona glomerulosa of dexamethasone- and ACTH-administered rats were investigated. Morphometry showed that both treatments induced a noticeable atrophy of the zona glomerulosa and its parenchymal cells, which is mainly due to the decrease in the smooth endoplasmic reticulum and the mitochondrial compartment. Radio-immunological studies indicated that in the treated rats the plasma aldosterone concentration was significantly decreased. Combined sodium repletion and timolol maleate administration provoked more intense effects than the single treatments. These data confirm the contention that both Na/K balance and the renin-angiotensin system are involved in the maintenance of the growth and steroidogenic capacity of the rat zona glomerulosa, with interfering without the hypothalamo-hypophyseal-adrenal axis.

Effects of ACTH on the zona glomerulosa of sodium-loaded timolol maleate-treated rats: stereology and plasma hormone concentrations

The effect of chronic ACTH administration on the growth and aldosterone secretion of the zona glomerulosa of sodium-loaded timolol maleate-treated rats was investigated by stereological and radioimmunological techniques. Combined sodium loading and timolol maleate administration induced a significant atrophy of the zona glomerulosa and its cells. The plasma concentration of aldosterone was significantly decreased, while that of corticosterone did not vary. ACTH administration completely reversed zona glomerulosa atrophy, and the plasma concentration of corticosterone was noticeably enhanced, whereas that of aldosterone underwent a further decrease. This data suggests that in the absence of the other adrenoglomerulotrophic factors, ACTH stimulates the growth of the zona glomerulosa, but transforms its parenchymal elements to a functional fasciculata cell type.

Ultrastructure of aldosterone secreting adrenal adenomata

Two adrenocortical adenomata causing Conn's syndrome were examined by electron microscopy. Adenomatous cells were arranged in small clusters and showed a rather different morphology, especially as far as mitochondria were concerned. Some cells contained mitochondria with lamellar and tubular cristae (zone glomerulosa-like cells), while other parenchymal elements displayed mitochondria with tubular and vesicular cristae (zona fasciculata-like cells). Both cells types were endowed with a quite well developed smooth endoplasmic reticulum, some lipid droplets and a prominent Golgi apparatus. Moreover, adenomatous cells with large masses of lipofuscin pigment granules were also observed (zona reticularis-like cells). These findings stress the structural heterogeneity of the Conn's adenomata.