Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “actionable alterations”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources
PubMed1997

Different effects of raised [K+]o on membrane potential and contraction in mouse fast- and slow-twitch muscle.

Increasing extracellular K+ concentration ([K+]o) from 4 to 7-14 mM reduced both tetanic force and resting membrane potential (Em) in isolated slow-twitch soleus and fast-twitch extensor digitorum longus (EDL) muscles of the mouse. The tetanic force-[K+]o relationships showed a greater force loss over 8-11 mM [K+]o in soleus than EDL, mainly because the Em was 2-3 mV less negative at each [K+]o in soleus. The tetanic force-resting Em relationships show that force was reduced in two phases: phase 1 (Em < -60 mV), a 20% force decline in which the relationships superimposed in soleus and EDL, and phase 2 (Em -60 to -55 mV), a marked force decline that was steeper in EDL than soleus. Additionally in phase 2, longer stimulation pulses restored tetanic force; the twitch force-stimulation strength relationship was shifted toward higher voltages; caffeine, a myoplasmic Ca2+ concentration elevator, increased maximum force; and twitch force fell abruptly. We suggest that 1) the K(+)-depressed force is due to reduced Ca2+ release resulting from an altered action potential profile (phase 1) and inexcitable fibers due to an increased action potential threshold (phase 2), and 2) K+ contributes to fatigue in both fast- and slow-twitch muscle when it causes depolarization to about -60 mV.

Animals↗
PubMed1988

Change of insulin action with aging in conscious rats determined by euglycemic clamp.

To clarify the mechanism responsible for age-related changes in insulin action, the euglycemic clamp technique was performed with graded doses of insulin in conscious rats aged 2, 4, 10, and 20 mo. Insulin binding (IB) to muscle membranes was also studied. Maximal response of insulin-induced glucose disappearance rate (Rd) was decreased significantly between 2 and 4 mo of age. Dose-response curves shifted to the right progressively up to 20 mo of age. However, IB to the muscle membrane diminished between 1 and 4 mo of age without a decrease thereafter. When Rd was plotted against insulin bound to the membranes, the resulting curves shifted to the right with aging, suggesting a coupling defect between the binding and effector unit. In conclusion, insulin action alters in rats between 2 and 20 mo of age. The most pronounced impairment in IB and maximal response of insulin-induced Rd occurs during early life stage (through maturation) and then a coupling defect seems to be superimposed with further aging. However, we cannot exclude the possibility that these changes may be secondary to obesity or reduced physical activity, rather than aging per se.

Aging↗
PubMed1992

Polyunsaturated fatty acids in cultured cardiomyocytes: effect on physiology and beta-adrenoceptor function.

This study was carried out to investigate the influence of the membrane fatty acid composition on the basal electrical and contractile activities and the response to beta-adrenergic stimulation of rat cardiac muscle cells in culture. Cells were grown for 3 days in a conventional serum culture medium and then incubated for 24 h in synthetic media containing either n-6 or n-3 as the sole source of polyunsaturated fatty acids (PUFA). The n-6/n-3 ratio in the phospholipids was 0.9 in the n-3 cells and 13.1 in the n-6 cells compared with 6.3 in controls cells. Such modifications did not alter action potentials and the main parameters related to contraction, although shortening was slightly accelerated in the n-6 cells. On the other hand, the positive chronotropic effect induced by isoproterenol was more pronounced (P less than 0.01) in n-3 cells than in n-6 cells. In addition, isoproterenol caused a decrease in contraction duration and in shortening and relaxation time that was less pronounced in n-6 than in control cells (P less than 0.01, P less than 0.01 and P less than 0.05, respectively). These results suggest that the PUFA balance in the phospholipids may contribute to modulate the cardiac adrenergic receptor system but not the membrane properties related to electro-mechanical functions.

Animals↗
PubMed2000

Effects of centrally applied somatostatin on pituitary adrenocorticotropes in female rats.

Effects of intracerebroventricular (i.c.v.) application of somatostatin (SRIH-14 or SRIH-28) on growth and function of pituitary adrenocorticotropes (ACTH cells) were examined in adult female Wistar rats. Animals were subjected to i.c.v. administration of three 1-microg doses of SRIH-14 or SRIH-28 dissolved in 5 microl saline every second day. Controls were treated in the same way with the same volume of saline only. ACTH-producing cells were studied using the peroxidase-antiperoxidase (PAP) immunohistochemical procedure; blood samples were collected for hormone analyses 5 days after the last injection. SRIH-28 treatment decreased (p < 0.05) all morphometric parameters compared to control rats. Volume of ACTH cells decreased by 10%, nuclei by 36% and volume density by 13%. No significant changes (p > 0.05) in these parameters occurred after SRIH-14 treatment. Plasma concentration of ACTH in SRIH-28-treated rats was significantly lower (p < 0.05) than in control rats by 35%. In SRIH-14-treated rats, plasma concentration of ACTH was slightly, but not significantly (p > 0.05) increased by 13% compared to saline treatment. These observations suggest that centrally administered somatostatin-28, but not somatostatin-14, is specifically involved in the control of growth and secretory activity of ACTH cells in female rats. Thus, selective pharmacological manipulation of SRIH-28 receptors reached from CSF may affect ACTH activity without altering actions usually attributed to receptors sensitive to SRIF-14.

Adrenocorticotropic Hormone↗
PubMed2026

Circulating Tumor DNA in Breast Cancer: A Liquid Biopsy Revolution for Non-Invasive Genomic Profiling and Clinical Decision-Making.

Breast cancer remains the most frequently diagnosed cancer and a leading cause of cancer-related mortality among women worldwide, underscoring the need for accurate, minimally invasive biomarkers to support precision oncology. Conventional tissue biopsy remains the standard for molecular characterization but is limited by its invasiveness, inability to capture spatial and temporal tumor heterogeneity, and challenges in serial monitoring. Circulating tumor DNA (ctDNA), a tumor-derived fraction of cell-free DNA, has emerged as a promising liquid biopsy biomarker capable of providing real-time genomic information throughout disease progression. This narrative review examines recent advances in ctDNA biology, analytical technologies, clinical applications, current limitations, and future directions in breast cancer management. A structured literature search of PubMed/MEDLINE, Scopus, Embase, Web of Science, and Google Scholar identified relevant English-language publications from 2015 to 2026. Current evidence indicates that highly sensitive platforms, including digital PCR, BEAMing, and next-generation sequencing, can detect clinically actionable alterations in genes such as PIK3CA, ESR1, TP53, ERBB2, AKT1, and BRCA1/2. ctDNA has demonstrated particular utility in identifying minimal residual disease, monitoring therapeutic response, detecting emerging resistance mechanisms, and guiding targeted treatment selection in advanced breast cancer. However, applications in early cancer detection, population screening, and artificial intelligence-assisted clinical decision-making remain investigational. Widespread clinical implementation is constrained by low ctDNA abundance in early-stage disease, analytical variability, limited assay standardization, and cost considerations. Continued technological innovation, prospective multicenter validation, standardized testing protocols, and evidence-based clinical guidelines are essential to fully integrate ctDNA into routine precision breast cancer care.

breast cancer↗
PubMed2001

Pharmacology of airway afferent nerve activity.

Afferent nerves in the airways serve to regulate breathing pattern, cough, and airway autonomic neural tone. Pharmacologic agents that influence afferent nerve activity can be subclassified into compounds that modulate activity by indirect means (e.g. bronchial smooth muscle spasmogens) and those that act directly on the nerves. Directly acting agents affect afferent nerve activity by interacting with various ion channels and receptors within the membrane of the afferent terminals. Whether by direct or indirect means, most compounds that enter the airspace will modify afferent nerve activity, and through this action alter airway physiology.

Acetylcholine↗
PubMed2000

Retinoid signaling is essential for patterning the endoderm of the third and fourth pharyngeal arches.

The requirement of retinoic acid (RA) in the initial formation of the pharyngeal arches was investigated by treating headfold-stage mouse embryos with a pan-RAR antagonist in vitro and in vivo. This results in a complete absence of mesenchyme, arteries, nerves and epibranchial placodes of the 3rd and 4th pharyngeal arches, complete agenesis of the 3rd and 4th pouches and consistent lack of the 6th arch artery. Mesodermally derived endothelial cells are absent from the 3rd and 4th pharyngeal arch region and the distribution domain of EphA2 transcripts in mesodermal cells is shifted caudally. In situ hybridization with CRABPI, kreisler and EphA4 probes and the pattern of expression of a Wnt1-lacZ transgene show that neural crest cells (NCC) normally destined to the 3rd and 4th arches migrate ectopically. Most interestingly, the appearance of the 3rd and 4th arches is prevented by the antagonist only during a very narrow window of time, which does not correspond to the period of post-otic NCC migration. Both the timing of appearance and the nature of the defects in RAR antagonist-treated embryos indicate that migrating NCC and mesodermal cells destined to the caudal pharyngeal arches do not represent primary targets of RA action. Alterations in the endodermal expression pattern of Hoxa1, Hoxb1, Pax1, Pax9, Fgf3 and Fgf8 in response to the antagonist-induced block in RA signal transduction demonstrate for the first time that RA signaling is indispensable for the specification of the pharyngeal endoderm and suggest that this signaling is necessary to provide a permissive environment locally for the migration of NCC and mesodermal cells. Our study also indicates that the formation of the 2nd pharyngeal arch and that of the 3rd and 4th pharyngeal arches probably involve distinct RA-dependent developmental processes.

Animals↗
PubMed1999

The photodynamic and non-photodynamic actions of porphyrins.

Porphyrias are a family of inherited diseases, each associated with a partial defect in one of the enzymes of the heme biosynthetic pathway. In six of the eight porphyrias described, the main clinical manifestation is skin photosensitivity brought about by the action of light on porphyrins, which are deposited in the upper epidermal layer of the skin. Porphyrins absorb light energy intensively in the UV region, and to a lesser extent in the long visible bands, resulting in transitions to excited electronic states. The excited porphyrin may react directly with biological structures (type I reactions) or with molecular oxygen, generating excited singlet oxygen (type II reactions). Besides this well-known photodynamic action of porphyrins, a novel light-independent effect of porphyrins has been described. Irradiation of enzymes in the presence of porphyrins mainly induces type I reactions, although type II reactions could also occur, further increasing the direct non-photodynamic effect of porphyrins on proteins and macro-molecules. Conformational changes of protein structure are induced by porphyrins in the dark or under UV light, resulting in reduced enzyme activity and increased proteolytic susceptibility. The effect of porphyrins depends not only on their physico-chemical properties but also on the specific site on the protein on which they act. Porphyrin action alters the functionality of the enzymes of the heme biosynthetic pathway exacerbating the metabolic deficiencies in porphyrias. Light energy absorption by porphyrins results in the generation of oxygen reactive species, overcoming the protective cellular mechanisms and leading to molecular, cell and tissue damage, thus amplifying the porphyric picture.

Darkness↗
PubMed2001

Genetic variant of luteinizing hormone: impact on gonadal steroid sex hormones in women.

A common variant of the LHbeta subunit has a varying prevalence in various ethnic groups. The consequences of the presence of mutated luteinizing hormone (LH) concern borderline alterations in pituitary/gonadal function that could be mediated by an altered action of variant LH on gonadal steroidogenesis. A comparison of plasma concentrations of gonadal steroid sex hormones was completed in women heterozygous for variant LH and in women with the wild type of LH in three different age ranges. The sample was a randomly selected group of 177 normal women 16 to 72 years old. Variant LH was determined by immunofluorimetric methods using two combinations of monoclonal antibodies. The ratios of LH measured by the two assays indicated whether the subject was wild type homozygote, heterozygote or homozygote for the variant LHbeta allele. The carriers of the variant LH allele in the group of postmenopausal women showed higher serum testosterone levels than those with the wild type LH. This is in agreement with the clinical observations made previously showing a slightly higher androgenic action in the population with variant LH. No differences were detected in serum LH, FSH, epitestosterone and sex hormone binding globulin (SHBG).

Adolescent↗
PubMed1975

[Peculiarities of the development of chloramine induced pulmonary edema in rabbits in various age periods].

Rabbits under three weeks of age were found to be less tolerant to chloramine (CA) than adult rabbits. For them the lethal dose of CA was 40--50 mg/kg. They perished from intoxication with the symptoms of protracted collapse without any manifestations of edema. For older rabbits the lethal dose of CA was 60--70 mg/kg. Death occurred with phenomena of acute and sharp edema of the lungs. In young rabbits atypical edema of the lungs occurred only with the administration of very high doses of CA--200--250 mg/kg. Edematous fluid is present in small amount only; there is a prevalence of hemorrhage, this being possibly caused by a direct alterating action of the CA excreted through the lungs on the walls of the arterioles and capillaries of the vascular system of the lungs.

Age Factors↗
PubMed2004

Use and abuse of opioid analgesics: potential methods to prevent and deter non-medical consumption of prescription opioids.

Medicinal opiates can produce both analgesia and euphoria. The mood altering action of this class of drugs has led to their abuse (non-medical use), a problem compounded by their physical dependence and addictive qualities. The legitimate expansion of clinical opioid analgesic use for severe chronic non-malignant pain, together with the introduction of high-dose extended-release (modified-release) oral tablet formulations of opioids with good bioavailability, has created increased opportunities for the illicit use of these prescribed drugs. Such use is now a major societal problem, with an incidence that appears to exceed the use of street narcotics such as heroin in the US. This review highlights the extent of the illicit use of prescribed opiate analgesics and some of the steps, legal, educational and pharmaceutical, that can be taken to potentially reduce the risk of their misuse or diversion for abuse.

Analgesics, Opioid↗
PubMed1992

Interactions between MPTP-induced and age-related neuronal death in a murine model of Parkinson's disease.

Abiotrophy is hypothesized to explain the onset and time course of deficits in Parkinson's disease (PD) Abiotrophy includes: 1) exposure to agent(s) causing the death of dopaminergic nigrostriatal neurons (DNSns), 2) gradual death of DNSns with age, 3) summation of 1) and 2) until DNSn numbers fall below a threshold for detectable neurological deficits. Murine DNSn death following methyl-phenyl-tetrahydropyridine (MPTP) exposure occurs according to an exponential relationship while age-related death of DNSns occurs according to a second exponential relationship. Summing the two exponential losses overestimates experimental DNSn death showing a simple abiotrophic model is not sufficient. Aged murine DNSns greatly increase their dopamine synthesis and the density of their striatal axon terminals which may explain the above threshold. Murine DNSns die gradually after MPTP exposure and L-deprenyl treatment rescues MPTP-damaged DNSns by a previously undiscovered action, altering the abiotrophic interactions and possibly explaining the slowed progression of PD found with deprenyl treatment.

Aging↗
PubMed1991

Low serum T3 and raised reverse T3 levels in hepatic cirrhosis: role of glucagon.

Hepatic parenchymal tissue is known to be one of the major sites of thyroid hormone metabolism as well as glucagon action. Alterations in circulating thyroid hormone concentrations, as well as hyperglucagonemia, are well documented in subjects with hepatic cirrhosis and advanced liver dysfunction. Also, we have documented recently that hyperglucagonemia induced in normal subjects alters thyroid hormone metabolism, with lowering of serum T3 and a rise in serum reverse T3 (rT3) levels. Thus, it is conceivable that rising glucagon concentrations are responsible for altered thyroid hormone levels in hepatic cirrhosis. To examine this hypothesis, this study determined relationships between plasma glucose, glucagon, insulin, and insulin:glucagon ratio on one hand, and thyroid hormone concentrations on the other, in 51 subjects with hepatic cirrhosis. Significant negative correlations were noted between plasma glucagon and serum T3 (r = -0.418, p less than 0.001) as well as T3:T4 ratio (r = -0.627, p less than 0.0001), whereas significant positive correlations were observed between plasma glucagon and serum rT3 (r = 0.504, p less than 0.001) as well as rT3:T4 ratio (r = 0.644, p less than 0.0001). No such significant relationships were noted between either insulin, glucose and insulin:glucagon ratio on one hand and any of thyroid hormone indices on the other. Therefore, this study indicates that, in hepatic cirrhosis, circulating glucagon concentrations may play a major contributing role in induction of altered serum thyroid hormone concentration by influencing thyroid hormone metabolism.

Adult↗
PubMed1991

Effect of clofibrate treatment on hepatic prostaglandin catabolism and action.

Prostaglandins (PG) modulate hepatocyte glucose and lipid metabolism. Hepatocytes rapidly metabolize PG via beta-oxidation, terminating PG action. Clofibrate induces hepatic peroxisomal beta-oxidative activity, for which PG are substrates. To determine the effect of clofibrate-treatment on liver PG metabolism and action, hepatocytes were isolated from rats maintained on a control or clofibrate-supplemented (0.5%) diet for 7 to 9 days. Rates of PG catabolism were determined by high performance liquid chromatography resolution of [3H]PG from [3H]metabolites. Clofibrate treatment enhanced the rates of PGE2, PGF2, and PGD2 degradation by 85%, 278% and 137%, respectively. Rates of PG degradation were correlated with hepatocyte carnitine acetyltransferase activity, a marker of peroxisomal proliferation. Further evidence of enhanced hepatocyte peroxisomal beta-oxidation of PG after clofibrate-treatment was obtained by confirming loss of the 1-position carbon from [1-14C]PGE2 during PGE2 metabolism and failure of the carnitine acyltransferase inhibitor acetyl-DL-aminocarnitine to inhibit PGE2 metabolism. Associated with the faster degradation of PGE2 by hepatocytes from clofibrate-treated rats was loss of inhibition of hepatocyte glucagon-stimulated glycogenolysis by exogenous PGE2. Thus, clofibrate's induction of peroxisomal beta-oxidation is associated with accelerated catabolism of PG and decreased PG action. Alterations in PG breakdown provide a mechanism for modulating hepatic PG effects.

Animals↗
PubMed1978

[Effect of ionizing radiation on cerebral phosphodiesterase].

The authors examined the influence of x-ray irradiation on phosphodiesterase system in the brain of rats and the sensitivity of the enzyme to inhibitors (caffeine, theophyline, thyopental) and activators (imidozol). The animals (Wistar with weights of 150--200 gm/were irradiated singly with a dose of 737 r. Phosphodiesterase activity (PD) was determined by the method of Filburn and Carn (1972) at two substrate concentrations (1 and 100 microM). X-ray irradiation did not change PD with high Km, while the enzyme with low Km was reduced significantly and transitionaly. Caffeine, theophyline and thyopental inhibited more PD with low Km in the irradiated rats in comparison with the control nonirradiated rats. The activating effect of imidazol on PD with low Km was more marked in irradiated rats. These data could be interpreted in the light of the molecular mechanisms, determining the altered action of some drugs after x-ray irradiation.

Animals↗
PubMed1988

[Specific binding of a synthetic antioxidant from a series of spatially screened phenols, H3-phenozan, with isolated rat enterocytes].

Specific binding of gamma-(4 hydroxy-3,5-ditret. butyl-phenol) propionate (phenozan), a synthetic water-soluble screened phenol with antioxidant activity, with isolated rat enterocytes has been demonstrated. The Scatchard analysis of binding isotherms revealed two types of 3H-phenozan binding sites. It is concluded that the effect of synthetic screened phenol antioxidants on cellular activity is the result of two mechanisms of action--alteration of physicochemical properties of membrane lipids caused by the inhibitors of free-radical reactions and specific binding of these compounds to cell plasma membranes.

Animals↗
PubMed1985

Evaluation of covalent antisickling compounds by PO2 scan ektacytometry.

The ektacytometer, a device to measure erythrocyte flexibility, has been used to evaluate antisickling agents that covalently modify hemoglobin S (HbS). The instrument has been adapted to produce a continuous gradient of oxygen pressure in the measuring cuvette, which permitted the rapid determination of sickle cell rigidity over the complete oxygenation range. Inspection of curves allows classification of the compounds according to their mode of action: altering oxygen affinity or increasing deoxy-HbS solubility. Reagents that modify amino groups, thiols, and histidine, as well as a crosslinking agent, were examined. The method directly evaluates deoxygenated cell deformability rather than cell shape. Many of the compounds that are effective in preventing the morphological sickling of deoxygenated sickle cells do not necessarily restore cell deformability. The method also readily detects membrane damage brought about by covalent agents that nonspecifically derivatize membrane proteins. Cystamine and pyridoxal appear to improve deformability in deoxygenated SS cells at concentrations that do not damage the membrane. This method, which examines the intact cell, fills a gap in the available experimental techniques for drug evaluation, between studies of isolated hemoglobin and in vivo studies.

Antisickling Agents↗
PubMed1985

Comparative pharmacokinetics of doxycycline and oxytetracycline in patients with hyperlipidemia.

This study examines the pharmacokinetics of lipophilic drug doxycycline (Vibramycin) and water-soluble antibiotic oxytetracycline hydrochloride (Oxyterracyna) in patients with hyperlipidemia type IIa and type IV according to Fredrickson. Antibiotics were administered orally as a single dose and determined in plasma by a fluorimetric method. The calculations were performed by aid of a computer. Increased concentrations of doxycycline were found; they were higher in type IIa, as compared with type IV. Area under the curve (AUC) and peak concentrations as well as rate constant for elimination in subjects with type IV were significantly elevated; volumes of distribution and total body clearance were markedly diminished. Decreased concentrations of oxytetracycline, area under the curve, peak concentration and rate constant for elimination were observed in patients with type IV. In both types of hyperlipidemia volume of distribution was increased and half-life in patients with type IV was significantly prolonged. The findings show that hyperlipidemia can be an important factor of drug action. Alterations of pharmacokinetics of lipophilic doxycycline and hydrophilic oxytetracycline were contrasting.

Adult↗