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At least 361 records · Page 20Linked to original sources
PubMed2004

Self-administration of fentanyl, cocaine and ketamine: effects on the pituitary-adrenal axis in rhesus monkeys.

RATIONALE: Drugs of abuse can affect the functioning of the hypothalamic-pituitary-adrenal (HPA) axis. Acute administration of drugs that serve as reinforcers have been observed to stimulate the rat HPA axis, leading to the suggestion that these stimulatory effects may contribute to the development of drug-maintained behaviors. OBJECTIVES: To determine whether reinforcing drugs that are dissimilar with respect to their mechanisms of action have similar effects on HPA axis activity at doses that are self-administered. Rhesus monkeys were randomly assigned to self-administer the mu-opioid agonist fentanyl, the psychomotor stimulant cocaine, or the NMDA antagonist ketamine. METHODS: Each monkey was trained to press a lever in order to receive an intravenous injection of drug or saline. Blood samples were obtained before, during, and after the self-administration sessions and assayed for ACTH and cortisol by radioimmunoassay. RESULTS: Fentanyl, cocaine, and ketamine were each self-administered across a range of doses. However, the three drugs differed in their effects on ACTH and cortisol. Cocaine stimulated ACTH and cortisol secretion, a finding that is consistent with previous rat and primate studies. Self-administration of both fentanyl and ketamine inhibited HPA axis activity. HPA inhibition by fentanyl is consistent with other monkey and human studies, and contrasts with the stimulatory effects of mu-opioids in rodents. The inhibitory effect of ketamine on ACTH and cortisol secretion contrasts with findings in the few primate studies that have evaluated NMDA antagonists. Neither fentanyl nor cocaine, at doses that maintained maximum rates of responding, produced significant changes in ACTH and cortisol levels. CONCLUSIONS: There appears to be little commonality between different classes of abused drugs and their effects on the HPA axis, which calls into question the necessity for HPA axis stimulation in the reinforcement of drug-maintained behavior.

Adrenocorticotropic Hormone↗
PubMed2000

Experimental study of the subtalar joint axis: preliminary investigation.

An experimental study of the subtalar joint has been conducted with the aim of establishing its axis of movement as well as analysing the associated movement. For description of the axis, CT data for five positions of a single foot were reconstructed using a 3D programme, the 3D data was processed by Patran software. Measures of angular displacements were made from three amputated feet placed in a specially constructed foot frame. Four instantaneous axes of movement could be defined. Calculation of displacements showed an important rolling of the calcaneus (45 degrees). Tacking was evident in inversion, with an opposite displacement between the front and rear part of the calcaneus, whereas during eversion tacking affected only the rear part of the bone: these results were confirmed by 3D reconstructions. Henke's axis was described as that for the talonavicular joint, but acceptable for the subtalar joint. Several authors investigating the coordinates of this axis have reported large differences and described screw-like movements, the latter being incompatible with a fixed axis: instantaneous axes, however are compatible with a screw-like movement. The subtalar joint appears to work as a pivot joint during inversion and as a plane joint during eversion. Although Henke's axis has pedagogical value the subtalar joint has a series of instantaneous axes.

Adult↗
PubMed2005

Axis I disorders and personality disorders as risk factors for suicide.

There is a lack of psychological autopsy studies assessing the influence of axis I disorders on axis II disorders as risk factors for suicide. Therefore, we investigated the association between personality disorders, axis I disorders, and suicide. Psychiatric disorders were evaluated by a semi-structured interview including the Structured Clinical Interview for DSM-IV Axis I (SCID-I) and Personality Disorders (SCID-II) in 163 completed suicides (mean age 49.6 +/- 19.3 years; 64.4% men) and by personal interview in 396 population-based control persons (mean age 51.6 +/- 17.0 years; 55.8% men). In both genders, suicides significantly more often had personality disorders of all clusters than controls, also after adjustment for axis I disorders (p < 0.001, each). In addition, alcohol-related disorders, major depression, and co-occurrence of personality disorders of more than one cluster (men: OR = 16.13; women: OR = 20.43) remained independent predictors for suicide in both genders, "pure" cluster B personality disorders only in women and "pure" cluster C personality disorders only in men. In both genders, co-occurrence of personality disorders of more than one cluster contributed to risk of completed suicide after control for axis I psychiatric disorders and has to be considered as an independent risk factor for suicide.

Adult↗
PubMed1990

Anatomic correlations of the long-axis views in biplane transesophageal echocardiography.

The number of views obtainable during transesophageal echocardiography (TE) has been limited by the fixed position of the transducer at the end of the probe. This has confined standard TE studies to short-axis tomography of the heart and aorta. Recently, a biplane TE probe has become available that is capable of both long- and short-axis imaging. This study prospectively assessed the application of the long-axis plane of the biplane probe in providing complementary long-axis views in ambulatory patients. Six standard long-axis views could be obtained and were compared with corresponding anatomic sections to illustrate anatomic relations and facilitate structure identification. The long-axis views provide a better appreciation of the 3-dimensional nature of cardiac anatomy and function, especially in demonstrating the relation of vertically aligned structures.

Adult↗
PubMed1993

Recovery of the hypothalamic-pituitary-adrenal (HPA) axis in patients with rheumatic diseases receiving low-dose prednisone.

PURPOSE: To assess the status of the hypothalamic-pituitary-adrenal (HPA) axis in cortico-steroid-treated patients whose prednisone dose had been tapered to physiologic doses. PATIENTS AND METHODS: The design of the study was a retrospective chart review of 50 consecutive patients receiving 10 mg or less of prednisone daily at a university teaching hospital rheumatology clinic. Patients were given a rapid adrenocorticotropic hormone stimulation test, with cortisol levels obtained at baseline and after intravenous administration of cosyntropin. Charts were reviewed for duration of therapy, highest, current, and total cumulative steroid dose, and average daily steroid dose in each month of the preceding 2 years. RESULTS: Current steroid dose was the only significant indicator of HPA axis function. Patients receiving less than 5 mg of prednisone daily had a normal HPA axis response, whereas those receiving 5 mg or more had widely varied responses. Neither the total, the highest prednisone dose, nor the duration of therapy was a significant indicator of HPA axis recovery. CONCLUSIONS: Spontaneous recovery of the HPA axis is usual for patients who are taking prednisone at daily doses of 5 mg or less. Return of normal HPA axis function can be achieved without alternate-day therapy in patients whose disease allows tapering to daily prednisone doses of 5 mg or less.

Adult↗
PubMedDate not supplied

Axis IV: a reliable and valid measure of psychosocial stressors?

DSM-III axis IV, Severity of Psychosocial Stressors, has been a disappointment to many because of the apparently infrequent use of the axis in clinical and research settings. This report is a review of literature on the use, reliability, and validity of axis IV. Although the concept of multiaxial evaluation has considerable appeal, clinicians have not routinely used axis IV, possibly because they do not fully understand the complexities involved in making ratings. The relatively few published empirical studies on axis IV indicate modest reliability and limited validity, beyond the value in identifying severe psychosocial stressors for the purpose of planning clinical interventions. The results of this review have led the DSM-IV Multiaxial Issues Work Group to consider several options for major changes in the format of axis IV to be recommended to the DSM-IV Task Force.

Humans↗
PubMed1990

An ultraviolet-sensitive maternal mRNA encoding a cytoskeletal protein may be involved in axis formation in the ascidian embryo.

Ultraviolet (uv) irradiation of the vegetal hemisphere of fertilized eggs during ooplasmic segregation inhibits subsequent gastrulation and axis formation in ascidian embryos. The molecular basis of this phenomenon was investigated in by comparing in vivo protein synthesis and in vitro mRNA translation in normal and uv-irradiated embryos of the ascidian Styela clava. Analysis of protein synthesis by [35S]methionine incorporation, two-dimensional (2D) gel electrophoresis, and autoradiography showed that only 21 (or about 5%) of 433 labeled polypeptides were missing or decreased in labeling intensity in uv-irradiated embryos. The most prominent of these was a 30,000 molecular weight (pI 6.0) polypeptide (p30). Extraction of gastrulae with the nonionic detergent Triton X-100 showed that p30 is retained in the detergent insoluble residue, suggesting that it is associated with the cytoskeleton. Several lines of evidence suggest that p30 may be involved in axis formation. First, p30 labeling peaks during gastrulation, when the embryonic axis is being established. Second, axis formation and p30 labeling are abolished by the same threshold uv dose, which is distinct from that required to inactivate muscle cell development. Third, the uv sensitivity period for abolishing p30 labeling and axis formation are both restricted to ooplasmic segregation. In vitro translation of egg RNA followed by 2D gel electrophoresis and autoradiography of the protein products showed that p30 is encoded by a maternal mRNA. The translation of p30 mRNA was abolished by uv irradiation of fertilized eggs during ooplasmic segregation suggesting that this message is a uv-sensitive target. The results are consistent with the hypothesis that uv irradiation blocks gastrulation and axis formation by inhibiting the translation of maternal mRNA localized in the vegetal hemisphere of the fertilized egg.

Acetylcholinesterase↗
PubMed1976

Hinge-axis location and face-bow transfer for edentulous patients.

There are distinct advantages to locating the hinge axis for the edentulous patient by use of the modified Loma Linda hinge-axis locator. These include: (1) alteration of the vertical dimension of occlusion on the articulator may be accomplished since the opening or closing takes place around the patient's terminal hinge axis; (2) valid and verified centric and eccentric relation records may be obtained at an increased vertical dimension of occlusion that is in harmony with the patient's terminal hinge axis; (3) cusp-form posterior teeth can be articulated and verified in the mouth with minimal occlusal correction by use of a terminal hinge axis. Some disadvantages to the procedure may include: (1) the additional procedure of making a modeling compound clutch for hinge-axis location; (2) the initial modification of the edentulous trays to accommodate the recording device; and (3) the technique is used with the Whip-Mix articulator; however, it can be modified for use with other articulators.

Dental Equipment↗
PubMedDate not supplied

Interpretation and clinical significance of the QRS axis of the electrocardiogram.

The frontal plane QRS axis of the standard 12-lead electrocardiogram (ECG) is easily and accurately measured by the clinician. A simple method of estimating this axis is discussed. This axis is age-dependent. We reviewed the literature to determine if evidence exists of an association between an "abnormal" QRS axis and clinically significant myocardial disease. We also examined the literature for clinical correlation of a "normal" QRS axis with the absence of myocardial pathology. We found that although an abnormal QRS axis (falling outside the limits of +30 degrees and +90 degrees) occurs in a small number of normal individuals, its presence should prompt a thorough evaluation of all the parameters of the ECG to look for myocardial disease.

Cardiomyopathies↗
PubMed2005

Cholecystokinin tetrapeptide effects on HPA axis function and elevated plus maze behaviour in maternally separated and handled rats.

Deficits in the function of the hypothalamic-pituitary-adrenal (HPA) axis have been suggested to predispose to the development of depression and anxiety disorders. This is mirrored in the animal model "Maternal Separation (MS)" where the stress of repeated separation of rat pups from the dam during early postnatal development results in long lasting alterations in HPA axis function. Cholecystokinin increases serum concentrations of stress axis hormones and might be involved in the dam-pup interaction in rats. Therefore, we hypothesized that adult animals, which had been separated daily (postnatal days (PND) 2-14) for 180 min (MS180) would differ in HPA axis responsiveness to an intravenous challenge dose of cholecystokinin tetrapeptide (CCK-4) compared to handled rats, separated for 15 min daily. The study explored the effects of intravenous CCK-4 on elevated plus maze behaviour and HPA axis hormones. MS180 animals displayed reduced general activity but unaltered levels of open arm activity in the elevated plus maze. CCK-4 administration elevated general activity in the handled rats, while leaving MS180 rats unaffected. MS180 rats had increased baseline CRF mRNA expression in the paraventricular nucleus of the hypothalamus. When CRF mRNA was assessed in chronically catheter implanted and single housed rats, lower levels were found in the paraventricular nucleus of MS180 animals compared to handled animals and this parameter was not affected by CCK-4 treatment. Adrenocorticotropin concentrations in serum were equal in MS180 and handled rats and unaffected by CCK-4. Corticosterone serum concentrations were lower in saline treated MS180 rats compared to saline treated handled rats. CCK-4 injection raised serum corticosterone in MS180 rats to levels equal to the handled rats, while leaving handled rats unaffected. We suggest that the lower levels of hypothalamic CRF mRNA and serum corticosterone concentrations in MS180 rats might be due to the experimental set-up with chronic venous catheter implants and single housing. In conclusion, this study supports the hypothesis of elevated CCK sensitivity in separated rats as measured by corticosterone changes thus adding to the existing literature reporting early life stress having long-term impact on HPA axis function.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Patterns of axis II comorbidity in early-onset versus late-onset panic disorder in Japan.

Early onset of psychiatric disorders has been reported to be associated with increased familial risk or more severe clinical symptoms. In this study, we specifically examine the association between clinical severity and early versus late onset in panic disorder. We hypothesize the existence of differences in rates of axis II disorders in these two groups that will relate to clinical severity. Subjects were a consecutive clinical case series of 105 panic disorder patients (age, 18.3 to 70.9 years). Thirty-one panic disorder patients were classified as early onset (age of onset < or = 25 years) and 74 as late onset (age of onset >25). We compared symptomatology and rates of comorbid axis II disorders (diagnosed by structured clinical interview) between the early- and the late-onset groups. We found a statistically significant increase in the number of suicide attempts and likelihood of comorbid axis II disorders in the early-onset group compared to the late-onset group. In logistic regression analyses, cluster B personality disorders (PDs), especially borderline and histrionic, were statistically significantly associated with the presence of suicide attempts. The following limitations are present: first, we have not taken into consideration comorbidity of other axis I disorders, especially major depression. Second, there is imprecision associated with efforts to date the onset of panic disorder retrospectively. We conclude that comorbid axis II disorders are more likely to occur in early-onset panic disorder patients. Cluster B PDs, especially borderline or histrionic, may be associated with a high frequency of suicide attempts in this group. In clinical practice, efforts to aggressively detect and treat axis II disorders in early-onset panic disorder patients are warranted.

Adolescent↗
PubMed2004

Initiation of gastrulation in the mouse embryo is preceded by an apparent shift in the orientation of the anterior-posterior axis.

BACKGROUND: It is generally assumed that the migration of anterior visceral endoderm (AVE) cells from a distal to a proximal position at embryonic day (E)5.5 breaks the radial symmetry of the mouse embryo, marks anterior, and conditions the formation of the primitive streak on the opposite side at E6.5. Transverse sections of a gastrulating mouse embryo fit within the outline of an ellipse, with the primitive streak positioned at one end of its long axis. How the establishment of anterior-posterior (AP) polarity relates to the morphology of the postimplantation embryo is, however, unclear. RESULTS: Transverse sections of prestreak E6.0 embryos also reveal an elliptical outline, but the AP axis, defined by molecular markers, tends to be perpendicular to the long axis of the ellipse. Subsequently, the relative orientations of the AP axis and of the long axis change so that when gastrulation begins, they are closer to being parallel, albeit not exactly aligned. As a result, most embryos briefly lose their bilateral symmetry when the primitive streak starts forming in the epiblast. CONCLUSIONS: The change in the orientation of the AP axis is only apparent and results from a dramatic remodeling of the whole epiblast, in which cell migrations take no part. These results reveal a level of regulation and plasticity so far unsuspected in the mouse gastrula.

Animals↗
PubMed2005

Change in the locus of dynamic loading axis on the knee joint after high tibial osteotomy.

The purpose of this study was to visualise the locus of the dynamic loading axis on the knee joint, and to evaluate changes in this locus during gait after high tibial osteotomy (HTO) in three patients who underwent HTO for medial compartment osteoarthritis (OA) of a varus knee. The bone structure of the lower limb and the relative position of skin markers were acquired from CT images. Motion capture data was acquired using spherical skin markers. Skeletal model movement during gait was calculated based on the movement of the markers. The locus of the dynamic loading axis on the knee joint was defined as the point on the proximal tibia joint surface that intersected with the loading axis of the lower limb, which passed through the centre of the femoral head and the centroid of multiple points surrounded by the distal tibia joint surface contour. This system was able to visualise the locus of the dynamic loading axis on the knee joint and not only lateral but also anterior-posterior direction movement. After HTO, the locus shifted from a medial and posterior area of the medial joint edge of the knee to a central area of the knee joint surface. This indicates that HTO shifted the dynamic loading axis. Lateral movement of the dynamic loading axis in the early stance phase of gait was reduced within a year after HTO.

Aged↗
PubMed2006

Determination of subtalar joint axis location by restriction of talocrural joint motion.

The location of the subtalar joint axis is an important determinant of the mechanical function of the foot. The moments of muscle forces and of the ground reaction force about the subtalar joint are dependent upon the location of this joint axis. There is substantial variation in subtalar axis location across subjects, but current methods for determining its location are often invasive or involve expensive imaging protocols. A novel technique for location of the subtalar axis is presented in which the talocrural joint is passively immobilized so that motion of the tibia relative to the calcaneus can be used to estimate the subtalar axis. This paper presents results of cadaver testing in which accuracy of the technique was assessed by comparing helical axes computed from calcaneus-tibia bone motions to axes computed from calcaneus-talus bone motions. Only small motions at the talocrural joint were observed, and good estimates of the subtalar axis (errors less than 15 degrees and 2mm) were achieved in four of six specimens.

Aged↗
PubMed2006

The prognostic significance of horizontal plane QRS axis in elderly heart failure.

In order to investigate whether horizontal plane QRS axis predicts the prognosis in elderly heart failure, we studied 80 consecutive patients by clinical assessment, ECG, Doppler and echocardiography. All patients were followed up for 2 years, 12 died and 68 survived. Age, gender distribution, blood pressure, co-existing diagnoses and medication were all similar between those who died and those who survived. The NYHA classification was significantly worse, left ventricular (LV) cavity size was greater, LV systolic function was lower in those who died than in survivors, despite similar LV wall thickness. On ECG, heart rate, PR interval, QT interval and frontal QRS axis did not differ between the two groups. The QRS duration was significantly longer and the horizontal QRS axis projected to a substantially more posterior direction in those who died than in survivors. The sensitivity and specificity of a horizontal QRS axis < or =-30 degrees for predicting death in 2 years were 75% and 62%, respectively. The former is above the sensitivity of a NYHA > or =3 and the latter is above the specificity of a LV shortening fraction < or =20%. The combination of a QRS horizontal axis < or =-30 degrees and NYHA > or =3 predicted 2 year mortality with a sensitivity of 75% and specificity of 91%. In conclusion, a left posterior QRS axis of the horizontal plane in elderly heart failure indicates an adverse prognosis, particularly when combined with NYHA classification and echocardiographic assessment.

Aged↗
PubMed2005

The hypothalamic-pituitary-adrenal (HPA) axis in habitual smokers.

Nicotine is a strong activator of the hypothalamus pituitary adrenal (HPA) axis. Smoking of only two cigarettes consistently activates the HPA axis of habitual smokers. However, while being a habitual smoker only induces small changes of basal HPA axis activity, smoking induces an attenuated responsiveness of the HPA axis to psychological stress, but not to injection of corticotropin releasing hormone (CRH) or physiological load. The latter points to alterations at hypothalamic or other central structures. The further consequences of decreased HPA axis responsiveness are discussed. Chronic inflammation of the airways is a common consequence of habitual smoking, and smokers often present with low-grade systemic inflammation, which may be mediated by HPA axis alterations. However, habitual smokers' monocytes are reported to show an increased sensitivity towards the inflammation suppressing effects of cortisol, while on the one hand, inflammation of the airways appears to be relatively resistant towards glucocorticoid treatment. In conclusion, this pattern of attenuated cortisol responses and decreased glucocorticoid sensitivity may be causally related to disinhibition of inflammatory processes and thereby further stimulate adverse health outcomes, such as airway inflammation or atherosclerosis.

Atherosclerosis↗
PubMed2005

Assessment of HPA-axis function in posttraumatic stress disorder: pharmacological and non-pharmacological challenge tests, a review.

Posttraumatic stress disorder (PTSD) is typically accompanied by acute and chronic alterations in the stress response. These alterations have mostly been described in individuals under baseline conditions, but several studies have also used a challenge model to further assess the role of the hypothalamic-pituitary-adrenal (HPA) axis in the stress response. This paper reviews common methodology and research findings on HPA function in PTSD, and discusses the pathophysiological mechanisms underlying these findings. We reviewed the literature and selected all English-language, human subject, data driven, pharmacological and non-pharmacological challenge studies pertaining to the HPA axis, and in vitro leukocyte glucocorticoid receptor studies in adult PTSD subjects. Studies using a non-pharmacological stress paradigm (cognitive stress, trauma reminders) to stimulate the HPA axis showed an exaggerated cortisol response in PTSD. The most widely used pharmacological challenge with consistent results was the low dose dexamethasone-suppression test (DST). These DST studies showed enhanced cortisol suppression in subjects with PTSD. Different hypotheses have been purported to explain the alterations in HPA axis functioning in PTSD. The results of the reviewed challenge tests, however, did not exclusively support one of the hypothesized mechanisms. Further research assessing hormones at all levels of the HPA axis at both baseline and at challenge conditions with a proper stratification of study population, will be necessary for a better understanding of stress-responsivity on the level of the HPA axis in PTSD.

Cognition↗
PubMedDate not supplied

Surgeon accuracy in the selection of the flexion-extension axis of the elbow: an in vitro study.

The incorrect determination of the flexion-extension axis of the elbow may result in poor clinical outcomes for patients undergoing ligament repairs, joint arthroplasties, and procedures requiring articulated external fixators. The variability in the selection of the flexion-extension axis based on a visual approximation of bony landmarks on the distal humerus was studied within a group of surgeons. Three surgeons of different experience levels independently selected points through which they believed the flexion-extension axis passed on the medial and lateral surfaces of 23 distal humeri. One surgeon repeated the point selection on three separate occasions. These surgeon points were compared with an axis calculated by use of a computer-assisted method that relied on the centers of the trochlear sulcus and capitellum via digitization of these structures. Relative to the computer-generated flexion-extension axis, the error in the surgeons' selections resulted in a mean frontal plane angle of 1.5 degrees +/- 3.0 degrees valgus (range, 6.3 degrees varus to 9.6 degrees valgus) and a coronal plane angle of 1.6 degrees +/- 3.3 degrees external rotation (range, 8.3 degrees internal rotation to 10.2 degrees external rotation). These results suggest that the use of a computer-assisted surgical technique will allow a more accurate determination of the flexion-extension axis of the elbow, which may lead to improved clinical outcomes in patients treated with ligament repairs or reconstructions, elbow arthroplasties, or articulated external fixators.

Adult↗