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Biomedical subjects

K Jensen

Publications and source records attributed to K Jensen.

At least 19 recordsLinked to original sources
PubMed2006

Interlayer forces and ultralow sliding friction in multiwalled carbon nanotubes.

We describe interlayer force measurements during prolonged, cyclic telescoping motion of a multiwalled carbon nanotube. The force acting between the core and the outer casing is modulated by the presence of stable defects and generally exhibits ultralow friction, below the measurement limit of 1.4 x 10(-15) N/atom and total dissipation per cycle lower than 0.4 meV/atom. Defects intentionally introduced in the form of dangling bonds lead to temporary mechanical dissipation, but the innate ability of nanotubes to self heal rapidly optimizes the atomic structure and restores smooth motion.

Journal Article↗
PubMed2006

Tunable nanoresonators constructed from telescoping nanotubes.

We have created a tunable mechanical nanoscale resonator with potential applications in precise mass, force, position, and frequency measurement. The device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezo-controlled contact. By exploiting the unique telescoping ability of MWNTs, we controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and tuning its flexural resonance frequency.

Journal Article↗
PubMed2006

A new species of Aberrapex Jensen, 2001 (Cestoda: Lecanicephalidea) from Taeniura lymma (Forsskål) (Myliobatiformes: Dasyatidae) from off Sabah, Malaysia.

A new lecanicephalidean species of Aberrapex Jensen, 2001 is described from the blue-spotted fantail ray Taeniura lymma (Forsskål) collected off the eastern coast of Sabah in Malaysian Borneo. This is the first record of a lecanicephalidean tapeworm from the island of Borneo and the first record of Aberrapex from this host species. A. manjajiae n. sp. is easily distinguished from its two congeners, A. senticosus Jensen, 2001 and A. arrhynchum (Brooks, Mayes & Thorson, 1981) Jensen, 2001, based on its overall smaller size (928-1,971 vs 1,485-6,333 and up to 3,350 microm long, respectively) and fewer testes (10-19 vs 20-40 and 18-25, respectively). In addition, A. manjajiae n. sp. is readily distinguished from A. senticosus based on a more anteriorly positioned genital pore (76-85 vs 52-72% of proglottid length from posterior end) and its distal bothridial microthrix pattern. A. manjajiae n. sp. can be further distinguished from A. arrhynchum based on its smaller scolex (82-101 x 119-164 vs 177-186 x 233-326 microm). The host distribution of Aberrapex is expanded from the Myliobatidae to include the Dasyatidae.

Animals↗
PubMed2006

A randomized study of two interferon-beta treatments in relapsing-remitting multiple sclerosis.

OBJECTIVE: To investigate whether the efficacy of interferon-beta (IFNbeta) treatment of relapsing-remitting MS (RR-MS) was influenced by type, dose, and frequency of administration. METHODS: From June 1996 through October 1997, the authors offered participation to all Danish RR-MS patients who met the following criteria: definite MS, at least two relapses within 2 years, age 18 to 55, and an Expanded Disability Status Scale (EDSS) score of < or = 5.5. The study was multicenter, controlled, open-label, randomized, head-to-head comparing IFNbeta-1a 22 microg once a week (n = 143) with IFNbeta-1b 250 microg every other day (n = 158), both subcutaneously, for 24 months. Patients who declined randomization were offered treatment with IFNbeta-1b 250 microg every other day (n = 120). The primary end-points were the annualized relapse rate, the time to first relapse, and neutralizing antibody formation. The secondary endpoint was time to sustained progression. RESULTS: The annual relapse rates were virtually equal in the two arms of the randomized study (IFNbeta-1a: 0.70; IFNbeta-1b: 0.71); so were the time to first relapse and the time to sustained progression. In the nonrandomized patients (IFNbeta-1b), the annual relapse rate was not significantly different, but the time to progression was shorter. CONCLUSION: In this study, 250 microg interferon-beta-1b administered every other day did not prove clinically superior to once-a-week administration of 22 microg interferon-beta-1a.

Adjuvants, Immunologic↗
PubMed2006

Gamma-hydroxybutyrate--a drug of abuse.

Gamma-hydroxybutyrate (GHB) is a drug of abuse that causes euphoria, anxiolysis, and hypnosis. The recent rise in the recreational intake of GHB, as well as its association with 'drug rape', has turned the attention to GHB in acute hospital settings. Acutely admitted GHB intoxicated patients may display various levels of sedation or coma, but may also show paradoxical agitation, combativeness, or self-injurious behaviors. The symptoms can be nonspecific and the definite diagnosis therefore normally relies on the detection of GHB in blood or body fluids, which is an analysis that may not be promptly available. As a basis for understanding the clinical features of GHB intoxication and abuse, we here review the pharmacological and neurophysiological knowledge about GHB, which stems from decades of clinical and basic GHB research. In addition, we discuss the latest discoveries in the quest for distinct GHB receptors in the brain, and their possible implications for future therapies of GHB abuse.

Adjuvants, Anesthesia↗
PubMed2005

Asymptomatic adults and older siblings with biotinidase deficiency ascertained by family studies of index cases.

We report 32 biotinidase-deficient patients detected by family studies in the index cases. The study group consisted of 10 mothers, 4 fathers and 18 siblings. There were 17 individuals (3 mothers, 4 fathers and 10 siblings) with profound biotinidase deficiency (BD) (< 10% of mean normal activity) and 15 (7 mothers and 8 siblings) with partial BD (10-30% of mean normal activity). In the profound BD group, only three siblings were symptomatic. Dermatitis, microcephaly, developmental delay and convulsions were observed. The patients with partial BD did not have any clinical symptoms except one sibling with borderline IQ score. None of the parents was symptomatic. Family investigation of patients with BD is very important for the detection of asymptomatic patients who are at risk of exhibiting symptoms at any age. Careful evaluation of these untreated individuals with BD is important to obtain additional information about the natural history of this disorder and may provide clues to phenotype-genotype relationships and treatment regimes.

Adult↗
PubMed2005

Randomized phase II study comparing topotecan/cisplatin administration for 5 days versus 3 days in the treatment of extensive stage small cell lung cancer (SCLC).

BACKGROUND: Topotecan (T) is an active drug in SCLC. A combination of topotecan with cisplatin (DDP) was suggested to be highly synergistic. This phase II trial was initiated to assess the activity of T/DDP in chemotherapy-naive patients suffering from extensive disease small cell lung cancer (SCLC) and to compare the conventional 5-day regime with an experimental 3-day schedule. PATIENTS AND METHODS: A total of 86 patients were included. Patients were randomized to receive either T 1.0 mg/m2 d 1-5 and DDP 75 mg/m2 d 5 (arm A) or T 1.5 mg/m2 d 1-3 and DDP 75 mg/m2 d 3 (arm B). Six cycles were given at a 3-week interval. RESULTS: Data of 84 evaluable patients (67 males and 17 females) were analysed. All patients had metastatic disease. The best response rate was 61.9% in arm A and 59.5% in arm B. Median overall survival was 8.7 months in arm A and 7.6 months in arm B (p=0.6809). CONCLUSIONS: Combination of T and DDP is active in ED SCLC. Toxicity and median survival were comparable in both arms. Three days treatment seems to be similar to the 5 days regime.

Adult↗
PubMed2005

Nanocrystal-powered nanomotor.

We have constructed and operated a nanoscale linear motor powered by a single metal nanocrystal ram sandwiched between mechanical lever arms. Low-level electrical voltages applied to the carbon nanotube lever arms cause the nanocrystal to grow or shrink in a controlled manner. The length of the ram is adjustable from 0 to more than 150 nm, with extension speeds exceeding 1900 nm/s. The thermodynamic principles governing motor operation resemble those driving frost heave, a natural solid-state linear motor.

Journal Article↗
PubMed2004

Effect of short-term prefeeding and body weight on wheel running and responding reinforced by the opportunity to run in a wheel.

A biobehavioural analysis of activity anorexia suggests that the motivation for physical activity is regulated by food supply and body weight. In the present experiment, food allocation was varied within subjects by prefeeding food-deprived rats 0, 5, 10 and 15 g of food before sessions of lever pressing for wheel-running reinforcement. The experiment assessed the effects of prefeeding on rates of wheel running, lever pressing, and postreinforcement pausing. Results showed that prefeeding animals 5 g of food had no effect. Prefeeding 10 g of food reduced lever pressing for wheel running and rates of wheel running without a significant change in body weight; the effect was, however, transitory. Prefeeding 15 g of food increased the animals' body weights, resulting in a sustained decrease of wheel running and lever pressing, and an increase in postreinforcement pausing. Overall the results indicate that the motivation for physical activity is regulated by changes in local food supply, but is sustained only when there is a concomitant change in body weight.

Animals↗
PubMed2003

Electrophysiological assessment of sensations arising from the bladder: are there objective criteria for subjective perceptions?

PURPOSE: Initial bladder filling sensation, first and strong desire to void are subjective perceptions that occur periodically during the urine storage mode of bladder function, representing sensory input from the lower urinary tract. To our knowledge methods for evaluating sensory bladder function are not available. We studied a simple electrophysiological procedure for the objective assessment of bladder sensations using sympathetic skin responses and surface pelvic floor electromyography. MATERIALS AND METHODS: Informed consent was provided by 8 healthy male subjects, who were administered 20 mg. furosemide and 1 l. fluid to drink. Palmar and plantar sympathetic skin responses, and surface pelvic floor electromyogram were continuously recorded during bladder filling, voluntary pelvic floor contraction and voiding. RESULTS: First desire to void evoked simultaneous sympathetic skin responses and pelvic floor contractions. This pattern appeared periodically with the desire to void sensation as well as with strong desire to void at maximum bladder capacity and it correlated well with the subjective sensation of the subjects. Voluntary pelvic floor contraction decreased the subjective intensity of the desire to void sensation as well as sympathetic skin response activity for the same short period. During voiding sympathetic skin responses almost complete absence of sympathetic skin responses was observed. CONCLUSIONS: Sensations arising from the bladder induce combined activation of sympathetic skin responses and pelvic floor activity. This coherence indicates synchronized activation and inactivation of the autonomic and somatic pathways necessary for appropriate urine storage and coordinated voiding. Our observations may introduce a new approach for objectively assessing subjective sensations arising from the urinary tract.

Adult↗
PubMed2003

Food production and wastage in relation to nutritional intake in a general district hospital--wastage is not reduced by training the staff.

BACKGROUND AND AIMS: To assess the amount of food produced in a hospital kitchen and the amount wasted. To assess the amount of food eaten by patients in relation to their energy needs. To assess whether the food production and wastage could be reduced by training members of the staff. METHODS: The study was carried out in a general district hospital in Denmark. The amount of food produced in the hospital kitchen and returned uneaten (wasted) was determined. In a representative sample of patients, the energy expenditure was calculated and in the same patients, the energy and protein intake was determined. Following training of the hospital staff the first part was repeated. RESULTS: On average, 11.1 MJ and 112 g of protein were ordered per patient per day. From these amounts on average 3.1 MJ and 33 g protein were wasted per patient per day. The total average energy expenditure was calculated to be 7.5 MJ per patient per day; however, on average, the daily energy intake was only 4.5 MJ and daily protein intake 46 g per patient. Sixty percent of the patients showed evidence of malnutrition as judged from the hospital notes. However, the staff only drew attention to this in 20% of the cases. Following training of the hospital staff, a new investigation showed no significant changes in the amount of food ordered and wasted. CONCLUSION: Despite a supply of food, which was much higher than the patients' needs, the patients have only approx. 60% of their energy need covered. We suggest a reorganization of nutrition in hospitals, so that this is made the responsibility of specific staff members.

Aged↗
PubMed2003

Nitrogen removal in industrial wastewater by nitration and denitration--3 years of experience.

CPKelco ApS, Denmark is the largest pectin plant in the world and the second largest refined carrageenan plant. The products are used for texturising purposes, primarily within the food industry, but also within the pharmaceutical industry. The products are extracted from imported natural raw materials, like dried citrus peel and special seaweed plants. In the production processes a considerable amount of water and energy are used. The excess water from the production processes is led to CPKelco's own WWTP, which is one of the largest industrial WWTPs in Denmark. In order to obtain higher process stability and lower energy consumption in the WWTP, CPKelco decided to change the nitrogen removal process from a conventional nitrification/denitrification process to a nitration/denitration process, which comprises an oxidation of ammonium to nitrite and a controlled reduction of nitrite to N2. Theoretically this process will decrease the oxygen consumption for oxidation by 25% and the use of carbon source for the reduction will be decreased by 40% compared to the conventional process. This paper presents and discusses the experiences and results from three year's continuous operation of the nitration/denitration process in an activated sludge plant, and the overall performance results are discussed in relation to the previous results. Accordingly the implementation of the nitration/denitration process was done successfully, and today the plant operates with much higher process stability than obtained before, and even the most stringent effluent requirements for nitrogen can be obtained.

Bioreactors↗
PubMed2001

PML protein isoforms and the RBCC/TRIM motif.

PML is a component of a multiprotein complex, termed nuclear bodies, and the PML protein was originally discovered in patients suffering from acute promyelocytic leukaemia (APL). APL is associated with a reciprocal chromosomal translocation of chromosomes 15 and 17, which results in a fusion protein comprising PML and the retinoic acid receptor alpha. The PML genomic locus is approximately 35 kb and is subdivided into nine exons. A large number of alternative spliced transcripts are synthesized from the PML gene, resulting in a variety of PML proteins ranging in molecular weight from 48-97 kDa. In this review we summarize the data on the known PML isoforms and splice variants and present a new unifying nomenclature. Although, the function/s of the PML variants are unclear, all PML isoforms contain an identical N-terminal region, suggesting that these sequences are indispensable for function, but differ in their C-terminal sequences. The N-terminal region harbours a RING-finger, two B-boxes and a predicted alpha-helical Coiled-Coil domain, that together form the RBCC/TRIM motif found in a large family of proteins. In PML this motif is essential for PML nuclear body formation in vivo and PML-homo and hetero interactions conferring growth suppressor, apoptotic and anti-viral activities. In APL oligomerization mediated by the RBCC/TRIM motif is essential for the transformation potential of the PML-RARalpha fusion protein.

Alternative Splicing↗
PubMed2001

Correlation of intraoperatively irradiated volume and fibrosis in patients with soft-tissue sarcoma of the extremities.

PURPOSE: To investigate the influence of intraoperatively irradiated volume on soft-tissue fibrosis. METHODS AND MATERIALS: Fifty-three patients with soft-tissue sarcoma of the extremities were treated with intraoperative radiotherapy (IORT) (median dose 15 Gy) and postoperative fractionated therapy (median dose 46 Gy). The median follow-up was 41.5 months (range 18-94). Late toxicity was classified according to the LENT-SOMA criteria. A Cox regression model was calculated to identify the parameters that could influence soft-tissue fibrosis Grade 3 or 4. Five parameters were observed: extent of surgical procedure, IORT in case of recurrence, extent of IORT volume, extent of IORT dose, and extent of postoperative volume. In addition, a logistic regression model was calculated to demonstrate the relationship between the IORT volume and fibrosis development. RESULTS: The overall survival rate after 5 years was 84%. The actuarial tumor control rate was 90% after 5 years. Eleven patients developed soft-tissue fibrosis. Five patients developed Grade 3 fibrosis and 1 patient developed Grade 4 fibrosis. Only the IORT volume had a significant influence on Grade 3 or 4 fibrosis development. An IORT volume of 210 cm(3) conveyed a 5% risk (confidence interval 1-20%) of the development of severe fibrosis. The risk of severe Grade 3 or 4 fibrosis increased to 50% (confidence interval 15-80%) if a volume of 420 cm(3) was irradiated. CONCLUSION: The effect of volume in patients treated with IORT was remarkable. The ratio of side effects was relatively low. The risk of soft-tissue Grade 3 or 4 fibrosis increased with the extent of the IORT volume. Compared with the literature, IORT provides excellent local control in these patients.

Adolescent↗