7,084 research outputs found
Quantum corpuscular corrections to the Newtonian potential
We study an effective quantum description of the static gravitational
potential for spherically symmetric systems up to the first post-Newtonian
order. We start by obtaining a Lagrangian for the gravitational potential
coupled to a static matter source from the weak field expansion of the
Einstein-Hilbert action. By analysing a few classical solutions of the
resulting field equation, we show that our construction leads to the expected
post-Newtonian expressions. Next, we show that one can reproduce the classical
Newtonian results very accurately by employing a coherent quantum state and
modifications to include the first post-Newtonian corrections are considered.
Our findings establish a connection between the corpuscular model of black
holes and post-Newtonian gravity, and set the stage for further investigations
of these quantum models.Comment: 26 pages, 4 figures. Typos corrected, references and clarifications
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Fatherhood and sperm DNA damage in testicular cancer patients
Testicular cancer (TC) is one of the most treatable of all malignancies and the
management of the quality of life of these patients is increasingly important, especially
with regard to their sexuality and fertility. Survivors must overcome anxiety and fears
about reduced fertility and possible pregnancy-related risks as well as health effects in
offspring. There is thus a growing awareness of the need for reproductive counseling
of cancer survivors. Studies found a high level of sperm DNA damage in TC patients
in comparison with healthy, fertile controls, but no significant difference between these
patients and infertile patients. Sperm DNA alterations due to cancer treatment persist
from 2 to 5 years after the end of the treatment and may be influenced by both the
type of therapy and the stage of the disease. Population studies reported a slightly
reduced overall fertility of TC survivors and a more frequent use of ART than the general
population, with a success rate of around 50%. Paternity after a diagnosis of cancer is
an important issue and reproductive potential is becoming a major quality of life factor.
Sperm chromatin instability associated with genome instability is the most important
reproductive side effect related to the malignancy or its treatment. Studies investigating
the magnitude of this damage could have a considerable translational importance in the
management of cancer patients, as they could identify the time needed for the germ
cell line to repair nuclear damage and thus produce gametes with a reduced risk for the
offspring
Erectile dysfunction in aging male
With the increasing longevity in men and women, sexual health concerns have become more and more important and demands for help are far more common than in the past. Erectile dysfunction's severity and prevalence both increase with aging: since erectile dysfunction is a symptom, physicians should diagnose underlying pathologies that might lead to it instead of focusing on finding a viable treatment. Cardiovascular alterations occur in the elderly, and might lead to erectile dysfunction because of penile blood flow impairment: diabetes, smoking, and sedentary life-style, being risk factors for vascular pathologies, can affect erectile function. Metabolic syndrome and psychological factors are highly prevalent in aging men, and might be other important determinants of erectile dysfunction.Drugs play a role in the pathogenesis of erectile dysfunction, as they can alter hormonal or vascular mechanics needed for achieving or maintaining erection. Alterations in penile vessels can be observed in the elderly: lack of androgens might lead to a reduction of smooth muscle cells content in the penis and an increase in the caliber of vascular spaces. Hypogonadism, when present, should be treated regardless of age; furthermore, synergistic effects have been found during testosterone replacement therapy when using an oral therapy with a PDE-5 inhibitor (sildenafil, vardenafil or tadalafil). These therapies are effective in the elderly, with no increase in the frequency of adverse events, and might also help in providing relief from lower urinary tract symptoms. (www.actabiomedica.it). © Mattioli 1885
Chromogranin A: From Laboratory to Clinical Aspects of Patients with Neuroendocrine Tumors
Background. Neuroendocrine tumors (NETs) are characterized by having behavior and prognosis that depend upon tumor histology, primary site, staging, and proliferative index. The symptoms associated with carcinoid syndrome and vasoactive intestinal peptide tumors are treated with octreotide acetate. The PROMID trial assesses the effect of octreotide LAR on the tumor growth in patients with well-differentiated metastatic midgut NETs. The CLARINET trial evaluates the effects of lanreotide in patients with nonfunctional, well-, or moderately differentiated metastatic enteropancreatic NETs. Everolimus has been approved for the treatment of advanced pancreatic NETs (pNETs) based on positive PFS effects, obtained in the treated group. Sunitinib is approved for the treatment of patients with progressive gastrointestinal stromal tumor or intolerance to imatinib, because a randomized study demonstrated that it improves PFS and overall survival in patients with advanced well-differentiated pNETs. In a phase II trial, pasireotide shows efficacy and tolerability in the treatment of patients with advanced NETs, whose symptoms of carcinoid syndrome were resistant to octreotide LAR. An open-label, phase II trial assesses the clinical activity of long-acting repeatable pasireotide in treatment-naive patients with metastatic grade 1 or 2 NETs. Even if the growth of the neoplasm was significantly inhibited, it is still unclear whether its antiproliferative action is greater than that of octreotide and lanreotide. Because new therapeutic options are needed to counter the natural behavior of neuroendocrine tumors, it would also be useful to have a biochemical marker that can be addressed better in the management of these patients. Chromogranin A is currently the most useful biomarker to establish diagnosis and has some utility in predicting disease recurrence, outcome, and efficacy of therapy
Non-alcoholic fatty liver disease connections with fat-free tissues: A focus on bone and skeletal muscle
The estimates of global incidence and prevalence of non-alcoholic fatty liver disease (NAFLD) are worrisome, due to the parallel burden of obesity and its metabolic complications. Indeed, excess adiposity and insulin resistance represent two of the major risk factors for NAFLD; interestingly, in the last years a growing body of evidence tended to support a novel mechanistic perspective, in which the liver is at the center of a complex interplay involving organs and systems, other than adipose tissue and glucose homeostasis. Bone and the skeletal muscle are fat- free tissues which appeared to be independently associated with NAFLD in several cross-sectional studies. The deterioration of bone mineral density and lean body mass, leading to osteoporosis and sarcopenia, respectively, are age-related processes. The prevalence of NAFLD also increases with age. Beyond physiological aging, the three conditions share some common underlying mechanisms, and their elucidations could be of paramount importance to design more effective treatment strategies for the management of NAFLD. In this review, we provide an overview on epidemiological data as well as on potential contributors to the connections of NAFLD with bone and skeletal muscle
Androgenetic alopecia: a review
Purpose
Androgenetic alopecia, commonly known as male
pattern baldness, is the most common type of progressive
hair loss disorder in men. The aim of this paper is to review
recent advances in understanding the pathophysiology and
molecular mechanism of androgenetic alopecia.
Methods
Using the PubMed database, we conducted a
systematic review of the literature, selecting studies pub-
lished from 1916 to 2016.
Results
The occurrence and development of androgenetic
alopecia depends on the interaction of endocrine factors and
genetic predisposition. Androgenetic alopecia is character-
ized by progressive hair follicular miniaturization, caused
by the actions of androgens on the epithelial cells of
genetically susceptible hair follicles in androgen-dependent
areas. Although the exact pathogenesis of androgenetic
alopecia remains to be clari
fi
ed, research has shown that it is
a polygenetic condition. Numerous studies have unequi-
vocally identi
fi
ed two major genetic risk loci for androge-
netic alopecia, on the X-chromosome AR
⁄
EDA2R locus and
the chromosome 20p11 locus.
Conclusions
Candidate gene and genome-wide association
studies have reported that single-nucleotide polymorphisms
at different genomic loci are associated with androgenetic
alopecia development. A number of genes determine the
predisposition for androgenetic alopecia in a polygenic fashion. However, further studies are needed before the
specific genetic factors of this polygenic condition can be
fully explaine
Erectile dysfunction and its management in patients with diabetes mellitus
Diabetes can be described as a syndrome of multiple closely related conditions induced by a chronic state of hyperglycaemia resulting from defective insulin secretion, insulin action or both. Chronic complications associated with diabetes (including neuropathy, vascular disease, nephropathy and retinopathy) are common, and of these, erectile dysfunction (ED) deserves special attention. ED and its correlation with cardiovascular disease require careful evaluation and appropriate treatment. PDE5 inhibitors (PDE5is) are an important tool for the treatment of ED, with new drugs coming onto the market since the late 90s. This review offers an overview of PDE5is and their use in treating ED in diabetes. We underline the differences between different types of PDE5i, focusing on available doses, duration of action, T ½, side effects and selectivity profiles in relation to patients with diabetes. We also discuss the link between diabetes and ED in presence of various associated cofactors (obesity, hypertension and its pharmacological treatments, atherosclerosis, hyperhomocysteinaemia, neuropathy, nephropathy, hypogonadism and depression). Finally a number of past and ongoing clinical trials on the use of PDE5is in patients with diabetes are presented to offer an overview of the appropriate treatment of ED in this condition
Linking type 2 diabetes and gynecological cancer: An introductory overview
Type 2 diabetes (T2D) is a chronic disease with a growing prevalence and a leading cause of death in many countries. Several epidemiological studies observed an association between T2D and increased risk of many types of cancer, such as gynecologic neoplasms (endometrial, cervical, ovarian and vulvar cancer). Insulin resistance, chronic inflammation and high free ovarian steroid hormones are considered the possible mechanisms behind this complex relationship. A higher risk of endometrial cancer was observed in T2D, even though this association largely attenuated after adjusting for obesity. A clear relationship between the incidence of cervical cancer (CC) and T2D has still not be determined; however T2D might have an impact on prognosis in patients with CC. To date, studies on the association between T2D and ovarian cancer (OC) are limited. The effect of pre-existing diabetes on cancer-specific mortality has been evaluated in several studies, with less clear results. Other epidemiological and experimental studies focused on the potential role of diabetes medications, mainly metformin, in cancer development in women. The correct understanding of the link between T2D and gynecologic cancer risk and mortality is currently imperative to possibly modify screening and diagnostic-therapeutic protocols in the future
The andrologist from medicine of reproduction to sexual medicine: the Italian experience
The main andrological areas of interest, male reproductive and - more recently sexual dysfunctions are most appropriately viewed as symptoms of the couple with medical, psychological and behavioural components that cannot be treated in a mechanical, purely medicinal manner (sexual medicine). The patient and his sexual partner must be active participants in a full continuum of care (medical sexology), the new challenge for the renewed and enriched field of andrology. In this field, the cooperation between basic researchers (such as geneticists, neurophysiologists, pharmacologists, ethologists) and a wide group of clinicians (such as endocrinologists, psychologists and psycho-sexologlsts, psychiatrists, urologists and gynaecologists) is of paramount importance for the andrologist at the dawn of the new field of medical sexology, which will be full of scientific gratification in the years to come
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