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H Knutsen

Publications and source records attributed to H Knutsen.

12 recordsLinked to original sources
PubMed2003

Fine-scaled geographical population structuring in a highly mobile marine species: the Atlantic cod.

Compared with many terrestrial and freshwater environments, dispersal and interbreeding is generally much less restricted in the marine environment. We studied the tendency for a marine species, the Atlantic cod, to be sub-structured into genetically differentiated populations on a fine geographical scale. We selected a coastal area free of any obvious physical barriers and restricted sampling to a 300-km region, well within the dispersal ability of this species. Screening 10 polymorphic microsatellite loci in 6 samples we detected a weak, but consistent, differentiation at all 10 loci. The average FST over loci was small (0.0023) but highly significant statistically, demonstrating that genetically differentiated populations can arise and persist in the absence of physical barriers or great distance. We found no geographical pattern in the genetic differentiation and there was no apparent trend of isolation by distance along the coastline. These findings lend support to the notion that low levels of differentiation are due to passive transport of eggs or larvae by the ocean currents rather than to adult dispersal, the latter being strongly dependent on distance.

Animals↗
PubMed2001

[Anagrelide in primary thrombocythemia].

BACKGROUND: Essential thrombocythaemia is a chronic myeloproliferative disease characterised by persistent thrombocytosis, i.e. platelet count > 600 x 10(9)/l and an increased risk of thromboembolic complications. Anagrelide may be used as a platelet-lowering agent in patients with essential thrombocythaemia. MATERIAL AND METHODS: At Akershus Central Hospital, ten patients below 60 years of age have been treated with anagrelide in the period 1997 through 2000. Patients were identified and data obtained from hospital files. Nine patients had been treated previously, mainly with hydroxyurea. Three patients were asymptomatic. RESULTS: Anagrelide was introduced with gradually higher dosage, while the dosage of hydroxyurea was gradually reduced. Four patients experienced slight and transient headache, five palpitations, and two diarrhoea. One patient had to limit the dose because of palpitations. The medication was discontinued in two patients because of side effects. The seven patients who tolerated the medication well, acquired platelet counts below 500 x 10(9)/l. No vascular complications have occurred. INTERPRETATION: Anagrelide is an efficacious drug in essential thrombocythaemia with relatively few side effects. Anagrelide should be considered a treatment of choice in patients below 60 years of age with essential thrombocythaemia.

Adult↗
PubMed2001

Genetic evidence for mixed origin of recolonized sea trout populations.

Anadromous brown trout along the Norwegian Skagerrak coast are genetically differentiated among streams, and there are indications of further substructuring within some streams. Among presumably long-standing populations there is a pattern of increased genetic differentiation with distance, indicating an isolation-by-distance effect. For trout that inhabit streams that have recently been recolonized after the extinction of trout because of acidification, we find evidence for a mixed origin of the recolonizing trout. Both the high levels of gametic phase disequilibrium and the clear deviation from the general pattern of increased genetic differentiation with distance that are seen in recolonized streams, are consistent with recent population admixture, and confirm the loss of the original populations of these acid streams.

Acid Rain↗
PubMed2000

Genetic differentiation among populations of the beetle Bolitophagus reticulatus (Coleoptera: tenebrionidae) in a fragmented and a continuous landscape.

The effect of habitat fragmentation on genetic differentiation among local populations of the fungivorous beetle Bolitophagus reticulatus (Coleoptera: Tenebrionidae) was studied in two contrasting landscapes: one heavily fragmented with forest fragments of variable size surrounded by inhabitable agricultural fields, the other an old forest providing a continuous habitat. The genetic structure of the beetle within each of the two contrasting areas was investigated by means of protein electrophoresis, screening four polymorphic loci in 20 populations from each area. In both areas there were significant genetic differences among local populations, but on average differentiation in the fragmented area was three times greater than in the continuous one, strongly indicating a genetic isolation effect of habitat fragmentation. These genetic results are in accordance with previous studies on dispersal in this species.

Alleles↗
PubMed1999

[A management program for primary thrombocytopenia].

Essential thrombocythemia is a chronic myeloproliferative disease characterized by persistent thrombocytosis and an increased risk of thromboembolic complications. Most patients are asymptomatic at the time of diagnosis. In this article guidelines for diagnosis and treatment of this disorder are presented on behalf of the Norwegian Society of Hematology. On the basis of a literature search in international databases (Medline) and international medical journals, articles have been selected according to their clinical relevance. The risk of major thrombosis is higher in patients older than 60 years and highest among those with a previous occlusive event. In individual patients there is no clear relationship between platelet count and risk of thrombosis. Low-dose aspirin (75-100 mg/day) is recommended to all patients with platelet count < 1,000 x 10(9)/l and in the absence of previous bleeding episodes. All patients with disease-related complications and asymptomatic patients with platelet count above 1,000-1,500 x 10(9)/l should receive cytoreductive treatment. Hydroxyurea is recommended for patients over 60 years of age. In younger patients, potential leukemogens should be avoided, and anagrelide or interferon-alpha is recommended.

Adult↗
PubMed1990

[Dilatation of esophageal stenoses].

During the period 1979-88, 129 patients (49 women and 89 men) were dilated for oesophageal strictures. The total number of dilatations was 811. The main causes were gastro-oesophageal reflux (54 patients), achalasia (17 patients) and malignant stenosis (27 patients). Almost all strictures were successfully dilated, but with short duration of effect in the malignant group. During the ten-year period, the method of dilatation has changed from almost exclusively Eder-Puestow dilators to balloon dilators. Four perforations of the oesophagus were experienced with the use of Eder-Puestow dilators (448 dilatations), whereas no perforations were experienced with the use of balloon dilatation (363 dilatations). The article presents a follow-up study of 37 available patients from the 54 with gastro-oesophageal reflux. It is concluded that endoscopic dilatation is a safe and efficient treatment for oesophageal strictures.

Adolescent↗
PubMed1989

Effect of metoprolol on early exercise-induced ST-segment changes and ventricular arrhythmias in patients with suspected acute myocardial infarction.

One-hundred and ninety-seven consecutive patients admitted for suspected acute myocardial infarction were randomized to double-blind treatment with intravenous followed by oral metoprolol or matching placebo within 24 hours (mean 6.9 hours) after onset of symptoms. A symptom-limited exercise test was performed 15 days after admission in 132 patients (70 patients receiving metoprolol; 62 placebo). Patients treated with metoprolol had a lower observed frequency of exercise-induced ST-segment elevation (11.4% vs. 22.6%; P less than 0.05) and less ventricular arrhythmias (7.1% vs. 19.4%; P less than 0.05) on the predischarge exercise test compared to placebo-treated patients; however, ST-segment depressions were equally distributed to the two treatment groups. Mean exercise capacity was the same in the two groups. Early administration of metoprolol to patients with suspected acute myocardial infarction reduces early exercise-induced parameters related to a bad prognosis and may therefore improve the long-term prognosis without reducing physical performance.

Arrhythmias, Cardiac↗
PubMed1989

Thyrotropin-releasing hormone antagonism of ethanol inebriation.

The effect of ethanol [1 g/kg per orally (p.o.) during 1 hr] after thyrotropin-releasing hormone (TRH) pretreatment (five doses of 20 mg p.o. during 30 hr preceding ethanol intake) was studied in a placebo-controlled, double-blind design in 11 healthy subjects. Computerized reaction tests measuring errors and reaction time, as well as clinical testing and a self evaluation (modified Osgood test) were performed before, 75, 150, and 225 min after ethanol intake. TRH treatment did not influence blood ethanol concentrations. The effect of ethanol to produce errors was substantially reduced in all three reaction tests after TRH treatment compared to placebo treatment. The reaction times were slightly increased in simple and four choice reaction tests and up to 20% increased in a complex test in the TRH-ethanol situation compared to the placebo-ethanol situation. The effects caused by ethanol were also significantly reduced in three clinical tests and in two subjective tests of inebriation by TRH treatment compared to placebo treatment. In conclusion the study demonstrated that several acute effects of ethanol intake in humans were reduced by TRH pretreatment which did not interfere with the blood ethanol concentration versus time curve.

Adult↗
PubMed1988

Radiological appearance of the ampulla of Vater.

The localized dilatation below the confluence of the bile and pancreatic ducts is known as the ampulla of Vater. The purpose of the present study was to delineate the radiological features of the choledochopancreaticoduodenal junction, with special reference to ampullar formation in this region. This was done by specimen radiography and review of the films from 255 examinations with endoscopic retrograde cholangiopancreatography. Full evaluation was possible in 200 cases. Ampullar dilatation was observed in only 9 (5.1%) of the 175 patients with a common terminal opening. No ampullar dilatation was observed in the 25 patients with separate openings of the duct. The appearance in the presence of ampullar dilatation is described. The distal end of the common bile duct, below its confluence with Wirsung's duct, has been known as the ampulla of Vater for nearly 130 years. This is a most important diminutive region of the human body, but there is little in the literature concerning its radiological presentation. In this report a radiological study is presented on the choledochopancreaticoduodenal junction.

Adolescent↗
PubMed1985

A double-blind multiple crossover trial evaluating a transdermal nitroglycerin system vs placebo.

Fifty-six patients with angina pectoris on effort participated in a 28-day study comparing a transdermal nitroglycerin system (TNS) against placebo. The protocol was based on a regular double-blind multi-crossover pattern. The variables recorded included daily sublingual nitroglycerin requirement, daily anginal attack frequency, and a subjective patient evaluation of each day on a visual analog scale. TNS dosage ranged from 10 cm2 (5 mg per 24 h) to 60 cm2 (30 mg per 24 h) based on the patient's dosage prior to commencement of the study. All other medication was continued unchanged. The results demonstrate improvement on active therapy in the patient group using greater than or equal to 20 cm2 TNS whereas no significant improvement in patients using 10 cm2 TNS was seen. In the higher dose group, the mean number of daily anginal attacks was 2.5 on placebo and 1.4 on active therapy (P less than 0.0001). Corresponding mean daily sublingual nitroglycerin requirement was 3.6 on placebo and 2.3 on active therapy (P less than 0.0001). Although TNS therapy was associated with significant improvement in the group using the higher dosage, the results suggest the development of tolerance on active therapy. The possibility of rebound effect and the absence of demonstrable efficacy in the low dose group require further investigation.

Administration, Topical↗