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Biomedical subjects

A Sigurdsson

Publications and source records attributed to A Sigurdsson.

At least 37 records · Page 2Linked to original sources
PubMed1999

A gene for lymphedema-distichiasis maps to 16q24.3.

Lymphedema-distichiasis (LD) is a dominantly inherited syndrome with onset of lymphedema at or just after puberty. Most affected individuals have distichiasis-fine hairs arising inappropriately from the eyelid meibomian glands-which is evident from birth. A study of three families with LD has shown linkage to chromosome 16q24.3, and subsequent analysis of the region for recombinant genes places the locus between D16S422 and D16S3074, a distance of approximately 16 cM. Possible candidate genes in this interval include the N-proteinase for type 3 collagen, PCOLN3; the metalloprotease PRSM1; and the cell matrix-adhesion regulator, CMAR.

Chromosomes, Human, Pair 16↗
PubMed1999

Effects of gender and acute dental pain on thermal pain responses.

OBJECTIVE: Considerable research suggests that females exhibit greater sensitivity to laboratory pain procedures than do males; however, whether the presence of acute clinical pain influences this sex difference in pain sensitivity has not been investigated. The present experiment investigated the effects of sex and acute dental pain on laboratory pain responses. DESIGN: Thermal pain onset and tolerance were determined in 46 dental patients (15 male, 31 female) experiencing pain due to acute irreversible pulpitis and in 33 healthy controls (13 male, 20 female). In addition, measures of mood and coping were obtained in all participants. All subjects participated in two experimental sessions. The first session took place immediately before the patients underwent endodontic treatment for relief of pulpal pain. The second session took place approximately 1-2 weeks later, when pulpitis patients were pain free after treatment. During each session, thermal pain onset and tolerance were assessed with a 1-cm2 contact thermode applied to the right volar forearm using an ascending method of limits. RESULTS: During both sessions, thermal pain onset and tolerance were lower in control females than in control males; however, male and female pulpitis patients did not differ in their thermal pain responses during either session. Pulpitis patients also showed greater affective distress than controls. CONCLUSIONS: These data suggest that the sex difference in thermal pain sensitivity frequently reported in pain-free subjects appears to be absent in patients presenting with acute dental pain. However, this effect cannot be explained solely based on the presence of clinical pain because the effect on pain threshold and tolerance persisted into session 2, when pulpitis patients were pain free. Potential explanations for these results are discussed.

Acute Disease↗
PubMed1998

High incidence of loss of heterozygosity in breast tumors from carriers of the BRCA2 999del5 mutation.

Germ-line mutation in the BRCA2 gene confers an increased risk of breast cancer. An elevation of additional genetic defects in tumors of patients with germ-line mutation in the BRCA2 gene compared with sporadic breast tumors has been reported. To evaluate the nature of the difference, we did detailed mapping of chromosomes 1p, 3p, 6q, 11, 13q, 16q, 17, and 20q, using microsatellite markers. We found that the frequency of loss of heterozygosity was similar at some chromosomal regions in the BRCA2 999del5 and sporadic tumors but significantly different at others. These others include chromosomal arms 3p, 6q, 11p, 11q, 13q, and 17p. Loss of heterozygosity mapping suggests that the same chromosome regions are involved in both tumor groups but at elevated frequencies in BRCA2 999del5 tumors. This higher frequency of genetic aberrations could pinpoint genes that selectively promote tumor progression in individuals predisposed to breast cancer due to the BRCA2 999del5 germ-line mutation. Accumulation of somatic genetic changes during tumor progression may follow a specific and more aggressive pathway of chromosome damage in these individuals.

BRCA2 Protein↗
PubMed1998

Sensitivity of patients with painful temporomandibular disorders to experimentally evoked pain: evidence for altered temporal summation of pain.

Temporomandibular disorders (TMD) represent a group of chronic painful conditions involving the muscles of mastication and the temporomandibular joint. Several studies have reported that TMD is associated with enhanced sensitivity to experimental pain. Twenty-three TMD subjects and 24 pain-free matched control subjects participated in a set of studies which were designed to evaluate whether the temporal integrative aspects of thermal pain perception are altered in TMD patients compared with control subjects. Specifically, we have examined in both TMD patients and in age- and gender-matched control subjects: (1) the time-course and magnitude of perceived pain evoked by the application of sustained 7-s noxious thermal stimuli (45-48 degrees C) to the face and forearm, (2) the central summation of C-fiber-mediated pain produced by applying brief trains of noxious heat pulses to the skin overlying the ventral aspect of the right palm and (3) the ability to discriminate small increments in noxious heat applied to facial and volar forearm skin. Data collected from these studies indicate that TMD patients show enhanced temporal integration of thermal pain compared with control subjects. TMD patients show greater thermal C-fiber-mediated temporal summation than pain-free subjects and they report a greater magnitude of sustained noxious heat pulses applied to either the face or the forearm than control subjects. In contrast to these findings, TMD and pain-free subjects are equally able to discriminate and detect small increments of heat applied to noxious adapting temperatures. These findings suggest that the augmented temporal integration of noxious stimuli may result from alterations in central nervous system processes which contribute to the enhanced pain sensitivity observed in TMD patients.

Adolescent↗
PubMed1997

In vitro susceptibility of Helicobacter pylori to protolichesterinic acid from the lichen Cetraria islandica.

With reference to the traditional use of Cetraria islandica (Iceland moss) for relief of gastric and duodenal ulcer, plant extracts were screened for in vitro activity against Helicobacter pylori. (+)-Protolichesterinic acid, an aliphatic alpha-methylene-gamma-lactone, was identified as an active component. The MIC range of protolichesterinic acid, in free as well as salt form, was 16 to 64 micrograms/ml.

4-Butyrolactone↗
PubMed1997

Sexual and physical abuse history in subjects with temporomandibular disorders: relationship to clinical variables, pain sensitivity, and psychologic factors.

Recent evidence suggests that a past history of physical and/or sexual abuse is more frequently reported among chronic pain populations; however, the prevalence of reported abuse has not been examined in patients with chronic orofacial pain caused by temporomandibular disorders (TMD). This study compares reported physical/sexual abuse among female TMD subjects recruited from the general population with that of age-matched female control subjects. The association of reported abuse with clinical pain, experimental pain responses, and psychologic variables was examined in the TMD group. Results indicated that a slightly but not statistically greater percentage of TMD subjects (44.8%) reported a history of sexual or physical abuse compared to control subjects (33.3%). Reported abuse among TMD subjects was not related to clinical pain or psychologic variables. Regarding experimental pain responses, TMD subjects reporting a history of abuse exhibited longer ischemic pain tolerances compared to those not reporting abuse; however, the groups did not differ on other experimental pain measures. Results indicate that the reported prevalence of physical/sexual abuse is similar among TMD subjects compared to other chronic pain populations; however, the relationship of abuse to clinical and psychosocial variables remains unclear.

Adolescent↗
PubMed1996

Pain sensitivity in patients with temporomandibular disorders: relationship to clinical and psychosocial factors.

OBJECTIVE: We have previously reported that patients with temporomandibular disorders (TMD) exhibit enhanced sensitivity to experimentally evoked pain (1); however, the clinical relevance of this increased pain sensitivity remains unclear. The purpose of this study was to investigate the relationship of experimental pain sensitivity to clinical and psychosocial variables among patients with TMD. DESIGN: Thirty-six TMD patients were studied, half of whom were pain sensitive (PS) and the other half pain tolerant (PT), based on their ability to tolerate an ischemic pain task. Responses to painful thermal and nonpainful visual stimuli as well as clinical/diagnostic symptoms and psychosocial variables were compared for the two groups (i.e., PS vs. PT). RESULTS: Results indicated that, compared with PT patients, the PS group exhibited greater sensitivity to thermal pain and rated innocuous visual stimuli as more intense. PS patients also reported greater clinical pain, but in general the groups did not differ on diagnostic and psychosocial measures. CONCLUSIONS: The results suggest that ischemic pain tolerance is a clinically relevant marker of pain sensitivity in TMD patients. These findings are consistent with the hypothesis that impairments in CNS inhibitory pathways may contribute to the pain associated with TMD.

Adult↗
PubMed1996

Application of contemporary methods for the use of international data in national genetic evaluations.

Increased international trade of genetic material from dairy cattle requires genetic evaluations across countries. Methods are discussed for comparing genetic evaluations of bulls computed in different countries. A system that combines information from several countries and produces routine international evaluations of dairy bulls is described, and possible ways of utilizing such international information in national breeding programs are presented. Important issues for international genetic evaluations are the estimation of genetic parameters within and across countries and the impact of imported bull evaluations on international rankings. Both issues are discussed in this article in view of recent research findings and potential future applications. Optimally, routine systems for international evaluation of the future will consider all economically important traits and serve different and well-defined breeding goals.

Animals↗
PubMed1996

The role of neurohormonal activation in chronic heart failure and postmyocardial infarction.

Chronic heart failure is a disabling and lethal disorder with high incidence and prevalence in Western societies. Treatment with angiotensin-converting enzyme (ACE) inhibitors and heart transplantations diminish both mortality and morbidity, although both still remain high. Increased understanding of some of the pathophysiologic mechanisms involved in the development of left ventricular dysfunction and the transition from asymptomatic systolic dysfunction to symptomatic heart failure has opened gates to new dimensions for the treatment of this disorder. The initial event in the pathophysiologic process is damage to the myocardium, most frequently a myocardial infarction. Almost simultaneously, activation of different neurohormonal systems occurs. The renin-angiotensin system and sympathetic nervous system are activated. Increased concentrations of hormones with counteractive activity have also been found, such as ANP and BNP. Interestingly, prolonged neurohormonal activation seems to occur only in patients with large infarcts or in patients with poor systolic function of the left ventricle. Moreover, available data from an echocardiographic study indicates that in patients with high concentrations of neurohormones in plasma a week after their infarction, left ventricular dilatation and systolic dysfunction of the left ventricle are highly likely to develop during long-term follow-up. Several studies have showed that ACE inhibitors are efficacious in chronic heart failure and among patients with reduced ejection fraction after myocardial infarction. What these patients have in common is prolonged neurohormonal activation, which theoretically may be harmful to myocardial cell structure and function. ACE inhibitors reduce the breakdown of angiotensin I to angiotensin II and increase the concentration of circulating bradykinins and prostaglandins. Further modulation of neurohormonal activity might be beneficial. Therefore, future treatment of chronic heart failure or asymptomatic left ventricular dysfunction might include beta-adrenergic blockers, neutral endopeptidase inhibitors, ANP, BNP, angiotensin II receptor antagonists, and modulators of sympathetic activity.

Chronic Disease↗
PubMed1995

Loss of heterozygosity on chromosome 9 in human breast cancer: association with clinical variables and genetic changes at other chromosome regions.

Primary breast tumors were tested for loss of heterozygosity (LOH), on chromosome 9p with microsatellite markers restricted to a 28 cM region including the MTS1 gene. LOH was found with at least 1 marker in 38% of the 201 cases analyzed. A high frequency of deletions was detected at the 9p23-p21 region, indicating a tumor suppressor gene(s) important for breast cancer tumorigenesis. Tumors with and without LOH on 9p were compared with respect to clinico-pathological factors using chi 2 analysis. Tumors with 9p LOH were significantly associated with high S-phase status and aneuploidy, but not with type, node status, estrogen and progesterone receptor content or age of the patients at diagnosis. Survival analysis showed that LOH at 9p did not significantly affect the survival rate of breast cancer patients. Our results indicate that the aberrations on 9p detected in this study are not of independent prognostic value. A significant association was found between LOH at 9p and LOH at chromosomal arms 3p and 6q, which is an additional contribution toward understanding the genetic events in breast tumor pathogenesis.

Alleles↗
PubMed1995

Herpes zoster infection presenting as an acute pulpitis.

A major reason for referral to an endodontic practice is management of pain. Most cases are diagnosed as being of pulpal or periapical origin. However, some turn out quite differently than their initial appearance. This case report presents a patient referred to the endodontic clinic because of symptoms mimicking an irreversible pulpitis. On examination no obvious cause of the symptoms could be found. The patient was treated conservatively after which a herpes zoster viral infection was diagnosed. This case stresses the importance of a thorough investigation of all signs and symptoms and the delay of definitive treatment until a diagnosis is made.

Acute Disease↗
PubMed1995

Neurohormonal activation and congestive heart failure: today's experience with ACE inhibitors and rationale for their use.

Treatment with angiotensin converting enzyme (ACE) inhibitors delays deterioration and improves survival in chronic congestive heart failure and left ventricular dysfunction. In two large placebo-controlled trials with survivors of acute myocardial infarction, but with left ventricular dysfunction, mortality was significantly lower in the ACE inhibitor arms, with risk reductions of 19% (with captopril) and 27% (with ramipril). A study of left ventricular dysfunction in more than 4000 patients resulted in significantly fewer myocardial infarctions among patients given enalapril than in those receiving placebo; the risk reduction was 24%. Knowledge of the degree of neurohormonal activation in patients with congestive heart failure (New York Heart Association [NYHA] Functional Class II-III) appears to be of major importance in determining the efficacy of ACE inhibition. Patients with plasma concentrations above normal show the greatest increase in survival when treated with ACE inhibitors compared to similarly treated patients with low or normal neurohormonal plasma levels as well as those treated with placebo or direct-acting vasodilators. In a study of 239 patients with NYHA Class IV heart failure, randomized to receive enalapril or placebo, mortality was significantly reduced in patients receiving enalapril who had plasma noradrenaline, adrenaline, angiotensin II, aldosterone, or atrial natriuretic peptide levels above median values. No significant differences in survival between groups were found in patients with hormone levels below the median. A study in 804 men with congestive heart failure who received either enalapril or hydralazine plus isosorbide dinitrate showed the greatest reduction in mortality after 2 years in enalapril treated patients with plasma noradrenaline levels > 900 pg.ml-1 or plasma renin levels > 16 ng.ml-1.h-1. These results indicate that the main rationale for ACE inhibition in chronic congestive heart failure, in left ventricular dysfunction, and after myocardial infarction is the modulation of prolonged neurohormonal activation. Knowledge of this effect may provide the means to forestall disease progression and thus offer long-term treatment benefits.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

Prevention of congestive heart failure by ACE inhibition in patients with acute myocardial infarction.

Ischaemic heart disease is a major cause of chronic heart failure in Western societies. Despite some progress in the treatment of heart failure, it is still a disabling disorder with both high mortality and high morbidity. The incidence of chronic heart failure has increased over the past decade, probably as a result of the recent success in the management of patients with acute myocardial infarction. The importance of measures with potential capacity to prevent the development of symptomatic heart failure may be best illustrated by the fact that, among patients with left ventricular dysfunction, the prognosis is much worse in those with symptomatic failure than in those who are asymptomatic. Recently, the efficacy of angiotensin converting enzyme (ACE) inhibitors after myocardial infarction has been studied in a number of large placebo-controlled trials. These studies indicate that patients with symptomatic or asymptomatic left ventricular dysfunction after an acute myocardial infarction should receive long-term treatment with an ACE inhibitor and that such treatment may improve survival, reduce the incidence of overt heart failure and reduce the risk of reinfarction.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

Neurohormonal activation in patients with acute myocardial infarction or chronic congestive heart failure. With special reference to treatment with angiotensin converting enzyme inhibitors.

Neurohormonal activation may provide a pathophysiological link between acute myocardial infarction and chronic congestive heart failure, and modulation of neurohormonal activity may be an important therapeutic target in these conditions. Plasma neurohormones were studied in 55 patients with acute myocardial infarction. Angiotensin II, noradrenaline and ANP were elevated in the early phase but tended to normalize during the first week in patients without signs of heart failure. In patients with heart failure angiotensin II and noradrenaline remained elevated for 1 month and ANP for 4-6 months. During head-up tilt, angiotensin II and noradrenaline increased most in patients with heart failure. In patients with a first myocardial infarction there was a positive correlation between sustained neurohormonal activity and infarct size. Almost complete suppression of plasma ACE activity was achieved within 30 min in 48 patients treated with intravenous enalaprilat, initiated within 24 h from the onset of infarction. The drug was tolerated in dosages of 1.0-1.2 mg given over 1-2h. Patients with systolic blood pressure between 100 and 110 mmHg incurred a greater risk of hypotension than those with higher blood pressure at baseline. Tolerance was not worse among patients treated with intravenous diuretics, metoprolol or nitroglycerin. A total of 98 patients were randomized to treatment with enalapril or placebo, initiated within 24 h from onset of infarction and continued for 4-6 months. During treatment there were no significant differences in plasma levels of angiotensin II, aldosterone, ANP or catecholamines between groups. Echocardiographic recordings were performed in 28 patients. Among patients on placebo there was a positive correlation between plasma levels of noradrenaline at days 5-7 and the increase in left ventricular volumes during the study period, and an inverse correlation between plasma aldosterone at days 5-7 and the increase in left ventricular ejection fraction during the study. No such correlation was found among patients on enalapril. ANP levels at 1 month correlated inversely with the left ventricular ejection fraction at the same time. Plasma neurohormones were measured in 223 patients with mild or moderately severe chronic heart failure, randomized to treatment with ramipril or placebo for 3 months. There was wide variation in hormone levels. Noradrenaline and aldosterone correlated inversely with exercise duration at baseline. Noradrenaline correlated positively with the degree of symptoms. Aldosterone and ANP were reduced with ramipril compared with placebo. Noradrenaline was reduced among patients with baseline levels in the highest tertile. Plasma hormones were also measured at peak exercise in 54 patients. Hormonal levels at rest correlated strongly with those at peak exercise.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗