PD-L1 marks a subset of melanomas with a shorter overall survival and distinct genetic and morphological characteristics

BACKGROUND

Programmed cell death ligand 1 (PD-L1) is a cell surface molecule that plays a critical role in suppressing immune responses, mainly through binding of the PD-1 receptor on T lymphocytes. PD-L1 may be expressed by metastatic melanoma (MM). However, its clinical and biological significance remains unclear. Here, we investigated whether expression of PD-L1 in MM identifies a biologically more aggressive form of the disease, carrying prognostic relevance.

PATIENTS AND METHODS

PD-L1 expression was analyzed by immunohistochemistry using two different antibodies in primary tumors and paired metastases from 81 melanoma patients treated at a single institution. Protein expression levels were correlated with PD-L1 mRNA, BRAF mutational status and clinical outcome. PD-L1(+) and PD-L1(-) subsets of the A375 cell line were stabilized in vitro and compared using gene expression profiling and functional assays. Results were confirmed using xenograft models.

RESULTS

PD-L1 membrane positivity was detected in 30/81 (37%) of patients. By multivariate analysis, Breslow thickness and PD-L1 membrane positivity were independent risk factors for melanoma-specific death {PD-L1 5% cutoff [hazard ratio (HR) 3.92, confidence interval (CI) 95% 1.61-9.55 P < 0.003], PD-L1 as continuous variable (HR 1.03, 95% CI 1.02-1.04 P < 0.002)}. PD-L1 expression defined a subset of the BRAF-mutated A375 cell line characterized by a highly invasive phenotype and by enhanced ability to grow in xenograft models.

CONCLUSIONS

PD-L1 is an independent prognostic marker in melanoma. If confirmed, our clinical and experimental data suggest that PD-L1(+) melanomas should be considered a disease subset with distinct genetic and morpho-phenotypic features, leading to enhanced aggressiveness and invasiveness.

High somatic mutation and neoantigen burden are correlated with decreased progression-free survival in multiple myeloma

Tumor-specific mutations can result in immunogenic neoantigens, both of which have been correlated with responsiveness to immune checkpoint inhibitors in highly mutagenic cancers. However, early results of single-agent checkpoint inhibitors in multiple myeloma (MM) have been underwhelming. Therefore, we sought to understand the relationship between mutation and neoantigen landscape of MM patients and responsiveness to therapies. Somatic mutation burden, neoantigen load, and response to therapy were determined using interim data from the MMRF CoMMpass study (NCT01454297) on 664 MM patients. In this population, the mean somatic and missense mutation loads were 405.84(s=608.55) and 63.90(s=95.88) mutations per patient, respectively. There was a positive linear relationship between mutation and neoantigen burdens (R²=0.862). The average predicted neoantigen load was 23.52(s=52.14) neoantigens with an average of 9.40(s=26.97) expressed neoantigens. Survival analysis revealed significantly shorter progression-free survival (PFS) in patients with greater than average somatic missense mutation load (N=163, 0.493 vs 0.726 2-year PFS, P=0.0023) and predicted expressed neoantigen load (N=214, 0.555 vs 0.729 2-year PFS, P=0.0028). This pattern is maintained when stratified by disease stage and cytogenetic abnormalities. Therefore, high mutation and neoantigen load are clinically relevant risk factors that negatively impact survival of MM patients under current standards of care.

Dominant Bacterial Phyla from the Human Gut Show Widespread Ability To Transform and Conjugate Bile Acids

Gut bacteria influence human physiology by chemically modifying host-synthesized primary bile acids. These modified bile acids, known as secondary bile acids, can act as signaling molecules that modulate host lipid, glucose, and energy metabolism and affect gut microbiota composition via selective antimicrobial properties. However, knowledge regarding the bile acid-transforming capabilities of individual gut microbes remains limited. To help address this knowledge gap, we screened 72 bacterial isolates, spanning seven major phyla commonly found in the human gut, for their ability to chemically modify unconjugated bile acids. We found that 43 isolates, representing 41 species, were capable of in vitro modification of one or more of the three most abundant unconjugated bile acids in humans: cholic acid, chenodeoxycholic acid, and deoxycholic acid. Of these, 32 species have not been previously described as bile acid transformers. The most prevalent bile acid transformations detected were oxidation of 3α-, 7α-, or 12α-hydroxyl groups on the steroid core, a reaction catalyzed by hydroxysteroid dehydrogenases. In addition, we found 7α-dehydroxylation activity to be distributed across various bacterial genera, and we observed several other complex bile acid transformations. Finally, our screen revealed widespread bacterial conjugation of primary and secondary bile acids to glycine, a process that was thought to only occur in the liver, and to 15 other amino acids, resulting in the discovery of 44 novel microbially conjugated bile acids. IMPORTANCE Our current knowledge regarding microbial bile acid transformations comes primarily from biochemical studies on a relatively small number of species or from bioinformatic predictions that rely on homology to known bile acid-transforming enzyme sequences. Therefore, much remains to be learned regarding the variety of bile acid transformations and their representation across gut microbial species. By carrying out a systematic investigation of bacterial species commonly found in the human intestinal tract, this study helps better define the gut bacteria that impact composition of the bile acid pool, which has implications in the context of metabolic disorders and cancers of the digestive tract. Our results greatly expand upon the list of bacterial species known to perform different types of bile acid transformations. This knowledge will be vital for assessing the causal connections between the microbiome, bile acid pool composition, and human health.

A cortico-cortical mechanism mediating object-driven grasp in humans

Humans and other primates demonstrate an exquisite ability to precisely shape their hand when reaching out to grasp an object. Here we used a recently developed transcranial magnetic stimulation paradigm to examine how information about an object's geometric properties is transformed into specific motor programs. Pairs of transcranial magnetic stimulation pulses were delivered at precise intervals to detect changes in the excitability of cortico-cortical inputs to motor cortex when subjects prepared to grasp different objects. We show that at least 600 ms before movement, there is an enhancement in the excitability of these inputs to the corticospinal neurons projecting from motor cortex to the specific muscles that will be used for the grasp. These changes were object- and muscle-specific, and the degree of modulation in the inputs was correlated with the pattern of muscular activity used later by individual subjects to grasp the objects. In a number of control experiments, we demonstrated that no change in excitability was observed during object presentation alone, under conditions in which subjects imagined grasping the object, or before movements involving the same muscles but without an object. This finding demonstrates a cortico-cortical mechanism subserving the transformation from the geometrical properties of an object to the outputs from motor cortex before grasp that is specific for object-driven movements.

Orientation-dependent stereo Wigner time delay and electron localization in a small molecule

Attosecond metrology of atoms has accessed the time scale of the most fundamental processes in quantum mechanics. Transferring the time-resolved photoelectric effect from atoms to molecules considerably increases experimental and theoretical challenges. Here we show that orientation- and energy-resolved measurements characterize the molecular stereo Wigner time delay. This observable provides direct information on the localization of the excited electron wave packet within the molecular potential. Furthermore, we demonstrate that photoelectrons resulting from the dissociative ionization process of the CO molecule are preferentially emitted from the carbon end for dissociative ²Σ states and from the center and oxygen end for the ²Π states of the molecular ion. Supported by comprehensive theoretical calculations, this work constitutes a complete spatially and temporally resolved reconstruction of the molecular photoelectric effect.

A computational model of drug delivery through microcirculation to compare different tumor treatments

Starting from the fundamental laws of filtration and transport in biological tissues, we develop a computational model to capture the interplay between blood perfusion, fluid exchange with the interstitial volume, mass transport in the capillary bed, through the capillary walls and into the surrounding tissue. These phenomena are accounted at the microscale level, where capillaries and interstitial volume are viewed as two separate regions. The capillaries are described as a network of vessels carrying blood flow. We apply the model to study drug delivery to tumors. The model can be adapted to compare various treatment options. In particular, we consider delivery using drug bolus injection and nanoparticle injection into the blood stream. The computational approach is suitable for a systematic quantification of the treatment performance, enabling the analysis of interstitial drug concentration levels, metabolization rates and cell surviving fractions. Our study suggests that for the treatment based on bolus injection, the drug dose is not optimally delivered to the tumor interstitial volume. Using nanoparticles as intermediate drug carriers overrides the shortcomings of the previous delivery approach. This work shows that the proposed theoretical and computational framework represents a promising tool to compare the efficacy of different cancer treatments.

Plasma albumin-to-globulin ratio before dry-off as a possible index of inflammatory status and performance in the subsequent lactation in dairy cows

The dry-off of dairy cows represents an important phase of the lactation cycle, influencing the outcome of the next lactation. Among the physiological changes, the severity of the inflammatory response can vary after the dry-off, and this response might have consequences on cow adaptation in the transition period. The plasma protein profile is a diagnostic tool widely used in humans and animals to assess the inflammatory status and predict the outcome of severe diseases. The albumin-to-globulin ratio (AG) can represent a simple and useful proxy for the inflammatory condition. In this study, we investigated the relationship between AG before dry-off and inflammation, metabolic profile, and performance of 75 Holstein dairy cows. Blood samples were collected from -62 (7 d before dry-off) to 28 d relative to calving (DFC) to measure metabolic profile biomarkers, inflammatory variables, and liver function. Daily milk yield in the first month of lactation was recorded. Milk composition, body condition score, fertility, and health status were also assessed. The AG calculated 1 wk before dry-off (-62 DFC) was used to retrospectively group cows into tertiles (1.06 ± 0.09 for HI, 0.88 ± 0.04 for IN, and 0.72 ± 0.08 for LO). Data were subjected to ANOVA using the PROC MIXED program in SAS software. Differences among groups observed at -62 DFC were almost maintained throughout the period of interest, but AG peaked before calving. According to the level of acute-phase proteins (haptoglobin, ceruloplasmin, albumin, cholesterol, retinol-binding protein), bilirubin, and paraoxonase, a generally overall lower inflammatory condition was found in HI and IN than in the LO group immediately after the dry-off but also after calving. The HI cows had greater milk yield than LO cows, but no differences were observed in milk composition. The somatic cell count reflected the AG ratio trend, with higher values in LO than IN and HI either before dry-off or after calving. Fertility was better in HI cows, with fewer days open and services per pregnancy than IN and LO cows. Overall, cows with high AG before dry-off showed an improved adaptation to the new lactation, as demonstrated by a reduced systemic inflammatory response and increased milk yield than cows with low AG. In conclusion, the AG ratio before dry-off might represent a rapid and useful proxy to evaluate the innate immune status and likely the ability to adapt while switching from the late lactation to the nonlactating phase and during the transition period with emphasis on early lactation.

Masseteric repetitive nerve stimulation in the diagnosis of myasthenia gravis

OBJECTIVE

(1) to develop a method for masseteric repetitive nerve stimulation (RNS) and to obtain normative data for amplitude and area decrement of the muscle (M) response. (2) To investigate myasthenia gravis (MG) patients with masseteric RNS. Masticatory muscles are frequently affected in MG, but no RNS test is available to investigate this district.

METHODS

Fifteen healthy subjects and 17 MG patients were examined. The masseteric nerve was stimulated by a monopolar needle (cathode), inserted between the mandibular incisure and the zygomatic arch, and a surface electrode (anode), on the contralateral cheek. Masseteric M response was recorded using surface electrodes on the muscle belly and below the mandibular angle. Stimuli were delivered at 3 Hz in trains of 9, at rest and after isometric effort.

RESULTS

Normal subjects: mean amplitude decrement was 0.3+/-1.2% at rest, and 1.9+/-1.3% after isometric effort.

PATIENTS

15 patients (88%) were positive on masseteric RNS; in 3 of these it was the only positive RNS test. The extent of decrement observed in masseter muscle was significantly greater than in trapezius muscle.

CONCLUSIONS

Masseteric RNS is a simple and well-tolerated procedure; it offers a new possibility in testing the cranial muscles in disorders of neuromuscular transmission.

The localization of facial motor impairment in sporadic Mobius syndrome

OBJECTIVE

To investigate the neurophysiologic aspects of facial motor control in patients with sporadic Möbius syndrome defined as nonprogressive congenital facial and abducens palsy.

METHODS

The authors assessed 24 patients with sporadic Möbius syndrome by performing a complete clinical examination and neurophysiologic tests including facial nerve conduction studies, needle electromyography examination of facial muscles, and recording of the blink reflex and of the trigeminofacial inhibitory reflex.

RESULTS

Two distinct groups of patients were identified according to neurophysiologic testing. The first group was characterized by increased facial distal motor latencies (DMLs) and poor recruitment of small and polyphasic motor unit action potentials (MUAPs). The second group was characterized by normal facial DMLs and neuropathic MUAPs. It is hypothesized that in the first group, the disorder is due to a rhombencephalic maldevelopment with selective sparing of small-size MUs, and in the second group, the disorder is related to an acquired nervous injury during intrauterine life, with subsequent neurogenic remodeling of MUs. The trigeminofacial reflexes showed that in most subjects of both groups, the functional impairment of facial movements was caused by a nuclear or peripheral site of lesion, with little evidence of brainstem interneuronal involvement.

CONCLUSION

Two different neurophysiologically defined phenotypes can be distinguished in sporadic Möbius syndrome, with different pathogenetic implications.

Characterization of the hypothalamo-pituitary-IGF-I axis in rats made obese by overfeeding

Obesity is coupled to several disturbances of the endocrine axes. It has previously been shown that genetically obese Zucker male rats have an impaired secretion of growth hormone (GH), probably originating from a primary reduction of hypothalamic GH-releasing hormone (GHRH) function and resulting in a decrease of GH gene expression and release. We sought to evaluate the somatotropic function in another model of experimental obesity. Normal male Sprague-Dawley rats were fed an energy-rich highly palatable diet for 7 months until they reached body weights overlapping those reported for obese Zucker rats. They were then evaluated for different indices of the hypothalamo-pituitary-somatomedin-C (IGF-I) axis. At the end of the overfeeding period, rats were divided into overtly obese (obese group) and overweight (overweight group) rats according to the degree of overweight and the Obesity Lee Index, while rats fed ad libitum with the standard pellet chow served as controls. Acute administration of a supramaximal dose of GHRH (2 micrograms/rat i.v.) elicited a significantly (at least P < 0.05) lower plasma GH rise in the overweight and obese groups compared with the controls although no difference was seen in the pituitary GH content and gene expression and plasma concentrations of free IGF-I in the two experimental groups vs the controls. In addition, evaluation of hypothalamic GHRH and somatostatin mRNAs (slot-blot hybridization) did not show any significant differences between the three groups. Of the different metabolic indices investigated, plasma glucose and insulin concentrations were significantly (P < 0.01) higher in the obese than in the overweight and control groups. A sharp decrease in plasma testosterone levels, together with a reduction in testis weight, was seen in both groups of rats fed the palatable diet compared with the controls. These findings underline the 'peripheral' feature of the hyposomatotropinism of rats chronically fed an energy-rich diet, and may account for the reversibility of the GH impairment in many obese subjects once a normal body weight has been restored. Moreover, the peripherally-driven hyposomatotropinism of these rats is in sharp contrast with the hypothalamic-driven GH secretory impairment of the obese Zucker rats.

Hypothalamic neuropeptide Y and galanin in overweight rats fed a cafeteria diet

We evaluated neuropeptide Y (NPY) and galanin (GAL) immunoreactivity (IR) and mRNA in the paraventricular and arcuate nucleus, respectively, in rats that became overweight (Ov) or not (NOv) when fed a cafeteria diet. After 2 months of diet, NOv rats showed a significant increase in NPY IR, whereas Ov rats showed a significant increase in GAL mRNA levels. None of these changes was present in rats overfed for 6.5 months. These differential changes in hypothalamic GAL and NPY transmissions may contribute to the different susceptibility of the two rat subpopulations to the weight-promoting effects of the hypercaloric diet.

Pathological yawning as a presenting symptom of brain stem ischaemia in two patients

Two cases of brain stem stroke involving the upper pons and the ponto-mesencephalic junction presented with transient excessive pathological yawning, associated with gait ataxia and in one subject with upper limb and facial hemiparesis. A causal relation is hypothesised between the brain stem lesion and pathological yawning, possibly related to denervation hypersensitivity of a putative brain stem yawn centre. Excessive yawning may herald brain stem ischaemia.

Comparison of attosecond streaking and RABBITT

Recent progress in the generation of ultra-short laser pulses has enabled the measurement of photoionization time delays with attosecond precision. For single photoemission time delays the most common techniques are based on attosecond streaking and the reconstruction of attosecond beating by interference of two-photon transitions (RABBITT). These are pump-probe techniques employing an extreme-ultraviolet (XUV) single attosecond pump pulse for streaking or an attosecond pump pulse train for RABBITT, and a phase-locked infrared (IR) probe pulse. These techniques can only extract relative timing information between electrons originating from different initial states within the same atom or different atoms. Here we address the question whether the two techniques give identical timing information. We present a complete study, supported by both experiments and simulations, comparing these two techniques for the measurement of the photoemission time delay difference between valence electrons emitted from the Ne 2p and Ar 3p ground states. We highlight not only the differences and similarities between the two techniques, but also critically investigate the reliability of the methods used to extract the timing information.

Muscle reinnervation following neonatal nerve crush. Interactive effects of glycosaminoglycans and insulin-like growth factor-I

This study shows that glycosaminoglycans promote muscle reinnervation following neonatal sciatic nerve injury. Such an effect appears to be mediated by insulin-like growth factor-1. The glycosaminoglycan moiety of proteoglycans is a constituent of the basal lamina active on nerve regeneration by means of the interaction with laminin and with several growth factors. We have previously shown that supplementation of glycosaminoglycans affects neuronal degeneration and regeneration. In this study we report that following neonatal lesion of the rat sciatic nerve glycosaminoglycan treatment promoted extensor digitorum longus muscle reinnervation with consequent improvement of muscle morphology. In saline-treated rats, reinnervation was only partial and there was a marked muscle fibre atrophy. In addition glycosaminoglycan treatment of lesioned rats increased insulin-like growth factor-I messenger RNA and protein in the reinnervated muscle, and insulin-like growth factor-I and insulin-like growth factor binding protein-3 plasma levels. Similarly, treatment of nerve lesioned rats with insulin-like growth factor-I promoted muscle reinnervation and prevention of muscle fibre atrophy, higher levels of insulin-like growth factor-I in the reinnervated muscle and of insulin-like growth factor-I and insulin-like growth factor binding proteins in plasma. These data suggest that glycosaminoglycans are potent stimulants of muscle reinnervation and that their effects may be mediated by increased levels of insulin-like growth factor-I.

Combined effects on tumor growth and metastasis by anti-estrogenic and antiangiogenic therapies in MMTV-neu mice

Breast tumor growth and metastasization are both hormone-sensitive and angiogenesis-dependent. Recent work carried out in our laboratory on a transgenic model of breast cancer displaying many similarities to its human counterpart, has shown that liposome-mediated angiostatin cDNA delivery partially inhibits both local and metastatic growth. However, it is now recognized that anti-angiogenesis strategy alone cannot completely arrest tumor growth and spread, and this led to the suggestion that approaches based on different molecular mechanisms could usefully be combined. In the present work, we investigated whether tamoxifen, a classical antiestrogen agent widely used in human therapy, could improve the results obtained with angiostatin alone. Further reduction of local growth was achieved with the combined regimen with respect to angiostatin or tamoxifen alone, while, as expected, no metastatic growth was detected in either group. We therefore conclude that a combination of angiogenesis inhibitors with antiestrogen drugs might be useful in humans and that other associations between conventional and gene transfer-mediated therapy are worth investigating and will soon become important components of anticancer therapy.

Worsening of ischemic damage in hearts from rats with selective growth hormone deficiency

The effects of growth hormone (GH) deficiency on cardiac function were studied in young male rats administered an anti-GH-releasing hormone (GHRH) serum from postnatal day 20 to 40. Dependence of heart abnormalities on GH deficiency was ascertained by giving a group of anti-GHRH serum-treated rats GH replacement therapy. Heart preparations from anti-GHRH serum-treated rats, undergoing low-flow ischemia, showed a progressive increase in left ventricular end-diastolic pressure with poor recovery of mechanical activity and increased coronary perfusion pressure upon reperfusion. Hearts from anti-GHRH serum + GH-treated rats, undergoing global reduction to the flow, showed only a minimal increase of left ventricular end-diastolic pressure and, upon reperfusion, cardiac mechanical activity recovered almost completely. Similar findings were also observed in heart preparations from control (normal rabbit serum-treated) rats. Infusion of acetylcholine (10(-6) M) into heart preparations in the preischemic period increased coronary perfusion pressure values more markedly in hearts from normal rabbit serum- and anti-GHRH serum + GH-treated rats than in those from anti-GHRH serum-treated rats. These results indicate that selective GH deficiency in young male rats renders the heart more sensitive to ischemic damage and leads to an impairment of cardiac muscarinic receptor function.

Sixteen weeks of hexarelin therapy in aged dogs: effects on the somatotropic axis, muscle morphology, and bone metabolism

Hexarelin (HEXA; 500 micrograms/kg/die, s.c.) was administered for 16 weeks to six old beagle dogs. The treatment consisted of three on-drug periods spaced by two off-drug periods. During each on period, the growth hormone (GH) peak response to HEXA initially increased and then dropped to pretreatment values. Each time, a wash-out interval restored the same pattern of GH responsiveness. HEXA significantly augmented the indices of spontaneous pulsatility of GH, but plasma insulin-like growth factor I levels did not change during treatment. HEXA apparently reduced bone resorption since it significantly decreased the urinary concentration of lysylpyridinoline, a bone matrix component. Bone formation apparently was not affected since unchanged levels of alkaline phosphatase were recorded. In three of six old dogs, HEXA induced an improvement of some morphological and biochemical muscular indices, evaluated in muscle specimens that, instead, remained unchanged in a group of young untreated controls. These findings indicate that HEXA effectively releases GH and primes the pituitary of old dogs, and strengthen the view that in aging, GH secretion may be restored by pharmacological means. It would also appear that HEXA-induced GH release improves some indices of body composition in old dogs.

Combined antiestrogen, antiangiogenic and anti-invasion therapy inhibits primary and metastatic tumor growth in the MMTVneu model of breast cancer

Treatments available to women with locally advanced breast cancer are unsatisfactory, since most patients succumb to metastatic spread. Therefore, there is a need to devise novel therapeutic combinations that effectively inhibit metastatization and to test them in animal models of breast cancer showing strong similarities with their human counterpart, including the ability to give rise to metastases. With these considerations in mind, tamoxifen (TAM), 4-hydrotamoxifen (4-HT) or liposome-complexed DNA constructs coding for antiangiogenic/anti-invasion proteins (angiostatin, TIMP-2, IFN-alpha(1), sFLT-1) were individually administered to MMTVneu transgenic mice. Significant inhibition of primary tumor growth was obtained with TAM (40% inhibition, P=0.049), angiostatin (85% inhibition, P=0.001) and TIMP-2 (60% inhibition, P=0.015). No lung metastasis was observed in any of these treated mice at 5 months, compared with a rate of 70% in control groups. These observations were the basis for designing a combined treatment with all these compounds. The association of angiostatin, TIMP-2 and TAM was greatly effective at the primary tumor level (90% inhibition, P=0.01). Moreover, all the mice treated with this association were metastasis free at a time point (6 months) in which seven out of nine control mice were either dead from disseminated cancer or showed lung metastasis. This combined therapy could become an important component of anticancer therapy in humans.

Somatostatin withdrawal as generator of pulsatile GH release in the dog: a possible tool to evaluate the endogenous GHRH tone?

Reportedly, somatostatin (SS) withdrawal is an effective generator of pulsatile GH release in mammals and it has been proposed that the amplitude of the GH bursts is related to the functional activity of GHRH-producing neurons. Our study was designed to test this hypothesis in the unanesthetized dog, under different conditions of endogenous GHRH function. First, we evaluated the ability of withdrawal of SS infusion to induce a GH secretory burst under basal conditions when GHRH function is thought to be enhanced, i.e. in young (2- to 3-year-old) dogs under sustained (30 days) caloric restriction (CR) or a 2-day fast. Secondly, we performed experiments in aged (11- to 17-year-old) dogs, in which hypothalamic GHRH secretion is thought to be reduced. Old dogs were evaluated under basal conditions, after a 2-day fast and after a 10-day administration of GHRH alone or followed by fasting. Both before and 14 h after the end of each experimental period, young and old dogs underwent a 3-hour (from 10.00 to 13.00 h) intravenous SS infusion (4 micrograms.kg-1.h-1). The secretory profile of GH was generated by 15-min sampling from 09.00 to 15.00 h. Under baseline conditions, SS withdrawal induced a significant burst of GH in young but not in old dogs. After CR, termination of SS infusion was followed in young dogs by a robust GH burst, significantly higher than that observed when dogs were fed ad libitum. In this instance, reduction of plasma IGF-I concentrations was unlikely to be responsible for the higher GH burst; the same pattern was present in the young dogs after a 2-day fast, when circulating IGF-I was unaltered. In old dogs, SS withdrawal did not modify baseline GH levels even after fasting, but induced a significant GH increase after GHRH priming. When GHRH priming was followed by fasting, SS withdrawal resulted in a GH burst higher than that occurring after fasting or GHRH alone. Altogether, these data support the view that the rebound rise in GH induced by withdrawal of SS is related to the endogenous GHRH tone. It is suggested that extrapolation of these findings to humans might permit probing, albeit inferentially, the endogenous GHRH tone under different physiologic or pathologic conditions.

Hypothalamo-pituitary-IGF-1 axis in female rats made obese by overfeeding

A gender-related impairment of the somatotrophic axis is present in obese Zucker rats, female rats being better preserved than males. We showed that another animal model of obesity, i.e., male rats made obese by feeding a hypercaloric diet had a reduced function of somatotrophic axis which was likely related to impairment of gonadal function. Aim of this work was that of studying the function of somatotrophic axis in female overfed rats and comparing it to that of male rats of the previous study. Sprague-Dawley female rats were fed an energy-rich palatable diet for seven months. At the end of overfeeding, according to the degree of overweight, rats were divided into overtly obese (Obese), overweight (Overweight) and Non-Obese, i.e. rats whose weights were similar to those of controls. Rats fed ad libitum with the standard pellet chow served as controls (Controls). Acute administration of a supramaximal dose of GHRH (2 microg/rat, iv) elicited a plasma GH rise similar to that of Controls in all the groups, except in Obese which had a lower GH response. Growth hormone responses after GHRH administration were inversely related to plasma levels of free fatty acids (FFA). Pituitary GH content and gene expression as well as hypothalamic GHRH and SS mRNA content, were similar in all experimental groups and in Controls and the same was true for plasma concentrations of free IGF-I. These results indicate that, similarly to obese female Zucker rats, also overfed female rats had a better preservation of the somatotrophic axis than their male counterparts. In diet-induced obese rats, also the etiology of the impairment of somatotrophic axis seems to be gender-related i.e. due to a reduction of gonadal function in males and to an elevation of FFA in females.

Association of postpartum uterine diseases with lying time and metabolic profiles of multiparous Holstein dairy cows in the transition period

The objective of this study was to assess how uterine disorders alter the lying behaviour and plasma biomarkers in dairy cows. 34 multiparous cows were retrospectively classified into three groups according to the first uterine disorder that cows were diagnosed with: retained placenta (RP), metritis (MET), or healthy (H; cows without any clinical disease). Lying time (LT) and duration of lying bouts (LB) were monitored between 6 weeks prior to and 8 weeks after calving via the AfiAct II pedometer. Blood samples were collected routinely between 14 days before and 28 days after calving. Data was analysed using Proc MIXED of SAS ver. 9.4. Regardless of grouping, both LT and LB were longer (P < 0.01) in the prepartum period (774 ± 16.6 min/day and 89.9 ± 2.1 min/bout) than in the first 28 days after calving (DFC; 653 ± 16.7 min/day and 63.7 ± 2.1 min/bout). Cows with RP had longer LT than healthy cows during the last 3 weeks before calving (837 ± 30.9 vs. 735 ± 27.1 min/day; P < 0.05). LT in cows with MET and healthy cows were not significantly different. The LB was similar among groups, averaging 76.1 ± 3.4 min/bout in healthy cows, 73.2 ± 3.8 min/bout in cows with RP, and 75.2 ± 3.7 min/bout in cows with MET (P > 0.05). Compared with healthy cows, cows with RP laid down longer and stood up for shorter times (P < 0.05), particularly before calving. In addition, cows with RP had increased mobilization of body stores and more pronounced inflammatory status, as demonstrated by plasma haptoglobin (P = 0.04) and albumin (P < 0.01) concentrations. Our data suggest that automatic monitoring of lying behaviour could help identify cows at increased risk of developing certain disorders, such as RP.

Growth hormone secretion is differently affected in genetically obese male and female rats

Growth hormone (GH) secretion is markedly blunted in obesity. Reportedly, genetically obese Zucker rats show a reduced GH secretion due to an impaired function of hypothalamic neurons producing the GH-releasing hormone (GHRH). The aim of this work was: (1) to compare the in vitro GH responsiveness to GHRH in genetically obese female versus male Zucker rats and, (2) to evaluate the function of hypothalamic GHRH and somatostatin and of pituitary receptors for these neurohormones as assessed by the effectiveness of GHRH and somatostatin on adenylate cyclase (AC) activity. Baseline GH secretion of pituitaries obtained from male and female obese rats was not different and similar to that present in lean counterparts. Stimulation with 10(-7) M GHRH elicited a significantly lower GH secretion from the pituitaries of obese male rats but induced a similar GH secretion from the pituitaries of lean and obese female rats. In these pituitaries, GH concentration was similar in obese versus lean male and female rats [corrected]. A sex-related difference was also evidenced when plasma concentrations of somatomedin C (IGF-I) were evaluated. Obese male rats had lower IGF-I concentrations than lean counterparts, while this was not the case for obese versus lean female rats. Evaluation of AC activity following GHRH disclosed a lower activation in obese than in lean male rats, whereas in the females the enzyme activation was higher in obese than in lean animals. Conversely, the inhibitory effect of somatostatin on forskolin-stimulated AC was similar in pituitary membranes of obese and lean rats of both sexes.(ABSTRACT TRUNCATED AT 250 WORDS)