Using an in vivo animal model of surfactant deficiency, the authors compared the effect of different ventilation strategies on oxygenation and inflammatory mediator release from the lung parenchyma.
...In adult rats that were mechanically ventilated with 100% oxygen, acute lung injury was induced by repeated lung lavage to obtain an arterial oxygen partial pressure < 85 mmHg (peak pressure/positive end-expiratory pressure PEEP = 26/6 cm H2O). Animals were then randomly assigned to receive either exogenous surfactant therapy, partial liquid ventilation, ventilation with high PEEP (16 cm H2O), ventilation with low PEEP (8 cm H2O), or ventilation with an increase in peak inspiratory pressure (to 32 cm H2O; PEEP = 6 cm H2O). Two groups of healthy nonlavaged rats were ventilated at a peak pressure/PEEP of 32/6 and 32/0 cm H2O, respectively. Blood gases were measured. Prostacyclin (PGI2) and tumor necrosis factor-alpha (TNF-alpha) concentrations in serum and bronchoalveolar lavage fluid (BALF) as well as protein concentration in BALF were determined after 90 and 240 min and compared with mechanically ventilated and spontaneously breathing controls.
Surfactant, partial liquid ventilation, and high PEEP improved oxygenation and reduced BALF protein levels. Ventilation with high PEEP at high mean airway pressure levels increased BALF PGI2 levels, whereas there was no difference in BALF TNF-alpha levels between groups. Serum PGI2 and TNF-alpha levels did not increase as a result of mechanical ventilation when compared with those of spontaneously breathing controls.
Although alveolar protein concentration and oxygenation markedly differed with different ventilation strategies in this model of acute lung injury, there were no indications of ventilation-induced systemic PGI2 and TNF-alpha release, nor of pulmonary TNF-alpha release. Mechanical ventilation at high mean airway pressure levels increased PGI2 levels in the bronchoalveolar lavage-accessible space.
Abstract
Disclosure: S. Mehta: None. R.A. Feelders: Advisory Board Member; Self; Corcept. Research Investigator; Self; Recordati, Strongbridge. L.J. Hofland: None. C. Campana: None. S.J. Neggers: ...None. X. Li: None. K. Wright: None. S. Skwiersky: None. J.D. Goldberg: None. H. Kim: None. D. Zagzag: None. N. Agrawal: Research Investigator; Self; Chiasma, Ascendis, Recordati.
The vast majority of prolactinomas are treated with dopamine agonists (DA) with excellent response, however DA resistance occurs in about 15% of prolactinomas. Surgery and radiotherapy are alternative treatments for these patients, but are not always successful. Somatostatin (SST) receptors have been studied with growing interest in prolactinomas. There are five SST receptor subtypes and mRNA expression analysis of prolactinomas has shown high expression of SST5 in comparison to SST1 and 2. The somatostatin analog, Pasireotide, which has a 40-fold greater binding affinity to SST5 compared to SST2 receptors, shows promising results in individual case reports of DA resistant and aggressive prolactinomas. This two-center retrospective cohort study investigated dopamine 2 (D2R), SST2a and SST5 receptor expression in surgical specimens of DA resistant prolactinomas. The study included consecutive surgical cases of adult patients with a diagnosis of DA-resistant prolactinoma at NYU Langone Health and Erasmus MC. DA resistance was defined as a failure to achieve normal prolactin (PRL) levels on maximally tolerated dopamine agonist doses and/or a failure to achieve 50% reduction in tumor size on coronal view. Co-secreting pituitary tumors were excluded to keep the somatostatin receptor analysis specific to prolactinomas. Receptor expression was scored on the basis of the well validated immunoreactivity score (IRS). This was done independently by two investigators by calculating the product of the percentage of positive cells and the intensity of the staining. 34 patients with average age 41.6 years and 19 (56%) males and 15 females are included in this analysis. Results: means (SDs) of pre-op PRL, pre-op image tumor size transverse and post-op PRL follow-up are respectively 1796 (4772) ng/mL in 33 patients; 2.23(1.61) cm in 15 patients; 108 (117) ng/mL in 17 patients. 31/33(94%) patients used DA preoperatively at various doses; 25/34 (74%) were DA resistant. Other indications include DA intolerance, apoplexy, cerebrospinal fluid leak. D2R was expressed in 94.1% (95% CI: 80.8%, 99.2%) of the cases. SST5 is expressed 61.8% (95% CI: 43.6%, 77.9%) of the prolactinomas and at a high level in a subset of SST5 positive cases. Only 17.6% (95% CI: 6.7%, 34.5%) of the prolactinomas express SST2a. SST5 expression has previously been studied in prolactinomas with variable expression. We show in this retrospective two center study a higher expression of SST5 receptor staining than previously demonstrated analyses and suggest SST5 staining to consider Pasireotide use in a subset of these patients. Larger prospective studies are needed to validate these findings.
Presentation: Friday, June 16, 2023
Abstract
Ghrelin, a 28-amino acid peptide gut hormone, occurs in acylated (AG) and unacylated (UAG) variants. AG is a GH secretagogue as well as being orexigenic and diabetogenic, acting via the ...growth hormone secretagogue receptor (GHSR1a) in the hypothalamus and pituitary. UAG counteracts these metabolic effects through unknown mechanisms. While screening for potential UAG receptor(s) we discovered previously uncharacterised interactions of AG and UAG with five cell membrane proteins (MPs), three of which are known to modulate metabolism. Here, we studied if two of these MPs (MP1 & 2) could modulate GHSR1a signalling by expressing their transgenes in HEK293 cells. As GHSR1a is coupled with calcium signalling via Gq proteins, aequorin luminescence was used to evaluate Ca2+ influx into the cells. Transfected cells were treated with either AG, UAG, or soluble parts of the MPs, or combinations thereof.
MP2 markedly enhanced the efficacy (~5.5-fold), but not the potency, of AG-induced Ca2+ influx, whereas MP1 had no effect on Ca2+ influx. Neither MP1 nor MP2 overexpression altered cellular GHSR1a levels. In the absence of GHSR1a, MP2 was unable to stimulate an AG-induced Ca2+ influx. UAG treatment (100nM) had no effect on GHSR1a-mediated Ca2+ influx in the presence or absence of MP2. MP2 is post-translationally modified and we suspected this to be important for its activity. However, removal or blockade of these modifications had no effect on the ability of MP2 to enhance GHSR1a signalling. Moreover, incubating the cells with soluble ectodomain of MP2 did not alter its effect on GHSR1a signalling. Nevertheless, induction of ectodomain shedding with PMA (0.4-1µM) dose-dependently reduced the AG-induced Ca2+ response to 0.5-0.2 of control levels (DMSO) in MP2-GHSR1a co-transfected cells. Unlike MP2, which has a transmembrane and intracellular domain, MP1 is attached to the plasma membrane via a glycosylphosphatidylinositol (GPI) anchor and lacks an intracellular domain. Since MP1 is otherwise structurally similar to MP2, we suspected that the intracellular domain of MP2 may be important for its function. Therefore, we expressed chimeras of MP2 and MP1 in which the GPI linkage site and the transmembrane/intracellular domains were exchanged. The MP2 ectodomain with a GPI-anchor had similar stimulatory effects on GHSR1a signalling as full-length MP2, whereas the MP1 ectodomain with MP2 transmembrane and intracellular domain only enhanced GHSR1a signalling by approximately 3-fold.
In conclusion, we have identified a membrane protein as a novel component of the ghrelin signalling pathway that markedly enhances the response of the ghrelin receptor to AG. Our current data suggest its ectodomain is important in mediating this effect. Studies are ongoing to fully delineate the mode of interaction and to determine the role of MP2 in ghrelin signalling in vivo.
Abstract
Introduction: Acromegaly is a rare disease due to growth hormone (GH)-secreting pituitary adenoma. GH and IGF-1 levels are usually congruent, indicating either remission or active disease, ...however a discrepancy between GH and IGF-1 may occur. We aimed to evaluate the outcome of acromegalic comorbidities in patients with congruent GH and/or IGF-1 levels vs discordant biochemical parameters. Methods: Retrospective analysis of the data of 3173 patients from the Liège Acromegaly Survey (LAS) allowed to include 190 patients from 8 tertiary referral centers across Europe, treated by surgery, with available data concerning diabetes mellitus (DM) and hypertension (HT) both at diagnosis and at last follow-up. We recorded for all the patients the number of antihypertensive and antidiabetic drugs used at the first evaluation and at last follow-up. Results: Ninety-nine patients belonged to the REM group (Concordant parameters), sixty-five patients were considered as GHdis and 26 patients were considered as IGF-1dis. At diagnosis, 63 patients (33.1%) had HT and 54 patients had DM (28.4%). There was no statistically significant difference in terms of number of anti-HT and anti-diabetic drugs at diagnosis versus last follow-up (mean duration=7.3+/-4.5years) between all 3 groups. Discussion: The results highlight that the long-term outcome of acromegaly does not tend to be more severe in patients with biochemical discordance in comparison with patients considered as in remission on the basis of concordant biological parameters, suggesting that patients with biochemical discordance do not require a closer follow-up.
Growth hormone (GH) can generate insulin-like growth factor-I production, provided that the liver encounters portal insulin as a permissive factor that switches on the liver sensitivity for GH. This ...phenomenon is important for a proper insight into the pathophysiology of diseases as type 1 and 2 diabetes which differ in portal insulin levels. Also, acromegaly and obesity can be better understood when this effect of insulin on liver sensitivity for GH is taken into account. Moreover, as all of these factors seem to influence activity of the 11β-hydroxysteroid dehydrogenase (11β-HSD) type 1 (and 2), an extensive knowledge on the interplay between them is crucial as nowadays treatment options for obesity using the 11β-HSD1 are emerging.
Changes in pulmonary edema infiltration and surfactant after intermittent positive pressure ventilation with high peak inspiratory lung volumes have been well described. To further elucidate the role ...of surfactant changes, the authors tested the effect of different doses of exogenous surfactant preceding high peak inspiratory lung volumes on lung function and lung permeability.
Five groups of Sprague-Dawley rats (n = 6 per group) were subjected to 20 min of high peak inspiratory lung volumes. Before high peak inspiratory lung volumes, four of these groups received intratracheal administration of saline or 50, 100, or 200 mg/kg body weight surfactant; one group received no intratracheal administration. Gas exchange was measured during mechanical ventilation. A sixth group served as nontreated, nonventilated controls. After death, all lungs were excised, and static pressure-volume curves and total lung volume at a transpulmonary pressure of 5 cm H2O were recorded. The Gruenwald index and the steepest part of the compliance curve (Cmax) were calculated. A bronchoalveolar lavage was performed; surfactant small and large aggregate total phosphorus and minimal surface tension were measured. In a second experiment in five groups of rats (n = 6 per group), lung permeability for Evans blue dye was measured. Before 20 min of high peak inspiratory lung volumes, three groups received intratracheal administration of 100, 200, or 400 mg/ kg body weight surfactant; one group received no intratracheal administration. A fifth group served as nontreated, nonventilated controls.
Exogenous surfactant at a dose of 200 mg/kg preserved total lung volume at a pressure of 5 cm H2O, maximum compliance, the Gruenwald Index, and oxygenation after 20 min of mechanical ventilation. The most active surfactant was recovered in the group that received 200 mg/kg surfactant, and this dose reduced minimal surface tension of bronchoalveolar lavage to control values. Alveolar influx of Evans blue dye was reduced in the groups that received 200 and 400 mg/kg exogenous surfactant.
Exogenous surfactant preceding high peak inspiratory lung volumes prevents impairment of oxygenation, lung mechanics, and minimal surface tension of bronchoalveolar lavage fluid and reduces alveolar influx of Evans blue dye. These data indicate that surfactant has a beneficial effect on ventilation-induced lung injury.
In order to ensure the best management of acromegalic patients with the varied therapeutic possibilities now available, identifying predictive factors of response to treatment is essential. In terms ...of imaging criteria, pituitary adenoma size and cavernous sinus invasion announce low chances of surgical cure. However, there are no recognized imaging predictive factors of somatotropinoma response to somatostatin analogue (SSA) therapy. Somatotropinomas are the only type of pituitary adenoma that often present as hypointense on T2-weighted MRI sequences. These T2-hypointense adenomas are usually smaller, more rarely invasive and correspond to higher IGF1 levels. However, an evaluation of the response, both anti-secretory, as well as anti-proliferative, of somatotropinomas to primary therapy with SSA has not been comprehensively studied and constitutes the purpose of our work. Acromegalic patients treated with SSA as primary therapy were included in this multicentric, international study, both prospectively and retrospectively. The duration of therapy varied from 3 to 12 months. The results of biological and MRI evaluations at baseline and after treatment were recorded. T2-weighted signal of the adenoma was classified as hypointense, isointense or hyperintense compared to the normal pituitary tissue or when the latter was not visualized, to the gray matter of the temporal lobe. For a quantitative assessment, ROI measurements of the adenoma, normal pituitary tissue, and gray matter were recorded. The ratio between adenoma and pituitary tissue/gray matter ROI was used in the statistical analysis to eliminate variations between different examinations. 106 patients were included in the study (52 male, 54 female). T2-weighted signal was hypointense for 76 adenomas (71.6%), isointense for 14 adenomas (13.2%), and hyperintense for 16 adenomas (15%). Treatment duration did not vary significantly between the T2-hypo-, iso- or hyperintense groups. However, T2-hypointense adenomas had a better biological response to SSA with a decrease in GH of 88.6% (vs 20.9% for T2-isointense and 23.8% for T2-hyperintense, p < 0.0001) and IGF1 % of 59.6% (vs 11.7% for T2-isointense and 33.2% for T2-hyperintense, p = 0.002). The anti-proliferative response was also better for T2-hypointense adenomas with a decrease of adenoma volume of 38.1% (vs 7.4% for T2-isointense and 2.48% for T2-hyperintense adenomas, p < 0.0001). Quantitative T2-measurement validated the results of the visual assessment. Adenomas with lower T2-weighted signal intensity had more important GH, IGF1% and volume reductions under treatment. T2-weighted signal intensity of pituitary adenomas assessed on the diagnostic MRIs of acromegalic patients allows the classification of somatotropinomas into different categories. T2-hypointensity appears to confirm itself as a marker of a more favorable response to primary therapy with SSA, in terms of both anti-secretory and anti-proliferative effects.
Modern intensive treatment modalities have led to an increasing number of survivors of childhood cancer, who are at risk for developing long-term sequelae. Since decline of renal function can develop ...subclinically, adequate surveillance is required for survivors previously treated with nephrotoxic treatment modalities. We describe a 34-year-old man, who had been treated for nephroblastoma (stage I) at the age of 5 years and who regularly visited the adult late-effects clinic for survivors of childhood cancer. Twenty years after his treatment for nephroblastoma glomerular function started to decline and progressive chronic kidney disease (CKD) stage 3 developed. It is important to recognise that survivors of childhood cancer can be at risk of developing long-term effects, including impaired renal function. Apart from regular surveillance by expert medical specialists dedicated to childhood cancer survivor care, more intensive communication with primary health care physicians is necessary to improve awareness of these issues in the growing cohort of childhood cancer survivors.
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