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Biomedical subjects

H Larsen

Publications and source records attributed to H Larsen.

At least 37 records · Page 2Linked to original sources
PubMed1997

Cementless AGC revision of unicompartmental knee arthroplasty.

Twenty-eight patients (29 knees) who had revision of a failed unicompartmental knee arthroplasty to total knee arthroplasty were evaluated. All revisions were made with cementless technique using the AGC prosthesis (Biomet, Warsaw, IN). Major osseous defects were found in 20 knees, and bone-grafting was used to fill the defects. Aseptic loosening and progression of osteoarthrosis were the main reasons for revision. The median follow-up period was 38 months. Twenty knees were excellent or good, four fair, and five poor. One tibial component had been revised because of loosening. Three knees with instability had been reoperated with a thicker polyethylene component, but one of these patients still suffered from instability, and revision with a constrained prosthesis was planned. One was revised after a deep infection. Two tibial components were suspected to be loose because radiographs exposed fluoroscopically revealed a complete radiolucent line under the component. The results with cementless revision and bone-grafting are comparable to the results achieved after cemented revision, and cementless revision is recommended in young patients and in patients with major bone loss.

Aged↗
PubMed1997

NR1 and NR2 subunit contributions to N-methyl-D-aspartate receptor channel blocker pharmacology.

The potencies of various N-methyl-D-aspartate(NMDA) receptor channel blockers were determined at recombinant NMDA receptors containing differing combinations of NR1 and NR2 subunits expressed in Xenopus laevis oocytes. When the NR1 subunit was varied (NR1e/NR2A or NR1b/NR2A), none of the 9 channel blockers tested displayed a statistically different affinity. In contrast, altering NR2 composition changed the affinities of several channel blockers. Three of 10 compounds displayed significantly higher affinities for NR1b/NR2C receptors than NR1b/NR2A receptors, and three of five compounds had higher affinity at NR1b/NR2C than NR1b/NR2B receptors. Both MK-801 and N-[1-(2-thienyl)cyclohyxyl]piperidine displayed identical affinities at all receptor subunit combinations tested. However, these two compounds displayed significantly slower rates of blockade and unblockade at NR1b/NR2C than at NR1b/NR2A receptors, perhaps reflecting the shorter mean open times of NR1/NR2C receptors. NR1b/NR2B and NR1b/NR2A were distinguished by one of five compounds tested. Taken together, these results indicate that NR2 subunits impart differing pharmacological profiles to NMDA receptors; thus, it may be possible to develop NMDA receptor channel blocker antagonists of greater subtype selectivity.

Acetamides↗
PubMed1996

Evidence for a further enterotoxin complex produced by Bacillus cereus.

Out of 321 strains of Bacillus cereus from several sources and isolated in four different countries, 239 (74%) produced cytotoxins. Only 127 (53%) of the cytotoxic strains were positive for the B-component gene of the haemolysin BL (enterotoxin) by polymerase chain reaction (PCR). Western blots using antiserum produced against enterotoxin(s) gave positive results for 199 (83%) of the cytotoxic B. cereus strains. On closer examination of seven of the strains, involved in food poisoning, we found that two strains completely lacked the L2- and B-components (of the haemolysin BL), and two strains were negative for the B-component gene by PCR, but were positive for the L2-component. From our experiments we concluded that there is at least one enterotoxin complex in addition to the haemolysin BL enterotoxin and enterotoxin T.

Animals↗
PubMed1996

Brain relapses in chemotherapy-treated small cell lung cancer: a retrospective review of two time-dose regimens of therapeutic brain irradiation.

The incidence of brain metastases secondary to small cell lung cancer (SCLC) is about 35% and the treatment strategy of brain irradiation with respect to dose and fractionation is controversial. In order to evaluate treatment outcome of brain irradiation in SCLC patients with brain relapse, we retrospectively evaluated all patients treated with brain irradiation in the eastern part of Denmark from 1988 to 1992 (PCI patients excluded). During this 5-year period, 101 evaluable patients were included (44 females, 57 males) (median age 61 years; range, 39-75 years). Forty-four patients, of whom 43 were in extracerebral complete remission (CR), received extended course (EC) brain irradiation (> 45 Gy, treatment schedule > 4 weeks). Fifty-seven patients received short course (SC) brain irradiation (< 30 Gy, treatment schedule < 1 week). Among the SC treated patients, 14 were in CR, 20 had partial remission or stable disease and 23 had progressive extracerebral disease. The median survival (from diagnosis of brain metastases) in the group receiving irradiation with EC (44 patients) was 160 days (range, 74-2021 days), while the 57 patients treated with SC had a median survival of 88 days (range, 20-948 days) (P = 0.00001, Log-Rank analysis). In a subgroup of 14 patients in extracerebral CR, receiving SC irradiation, the median survival was 83 days (range, 15-948 days). When the latter patients were compared to the 43 patients in CR in the group treated with EC, a statistically significant difference was shown (P = 0.034, Log-Rank analysis). Using Cox-hazard regression analysis with backward elimination, liver metastases and poor performance status were adverse prognostic signs, although the only significant parameters of survival were gender (female vs. male, relative risk of dying 1 and 1.52, P = 0.05) and schedule of brain irradiation (extended course vs. short course, relative risk of dying, 0.36 and 1, P < 0.001). Extended course irradiation of brain relapse secondary to SCLC seems in general to be of limited value, although a significant prolonged survival at approximately 7 weeks, was obtained. The prolongation of survival does not seem worthwhile considering the length of treatment time (5-6 weeks) compared to SC treatment (1 week). However, the data do not permit evaluation of the quality of life of the patients. This retrospective evaluation suggests the need for randomized trials with carefully planned quality-of-life assessments.

Adult↗
PubMed1995

Evaluation of the optimal duration of chemotherapy in phase II trials for inoperable non-small-cell lung cancer (NSCLC).

PURPOSE: To determine the optimal duration of chemotherapy in phase II trials for patients with non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: The time from start of treatment until achievement of response according to WHO criteria was determined retrospectively in 8 phase II trials. RESULTS: Response to chemotherapy consisting of 4 complete and 39 partial remissions was registered in 43 of 333 patients. The median time from treatment start to response was 54 days. On day 84 on-study, 35 of the responding patients (81%) had achieved the response. Forty-three responses (98%) had occurred by day 168 and only one patient (2%) accomplished a response after 168 days of treatment. The responses had a median duration of 151 days (range 28-1559 days). CONCLUSIONS: The data indicate that patients with NSCLC included in phase II trials who have not yet achieved a response to chemotherapy after 168 days on study have a low likelihood (2%) of a subsequent response. Hence, treatment cessation at this point should be considered for non-responding patients. Continuation of treatment from day 84 to day 168 resulted in response in only 7 patients out of the total of 43 responses noted (16%). Thus, the toxic effects of the chemotherapy in addition to the inconvenience of hospital visits renders it questionable whether it is worthwhile to continue treatment in patients with inoperable non-small-cell lung cancer beyond day 84 in the absence of response.

Adult↗
PubMed1995

Parental origin of the X chromosome, X chromosome mosaicism and screening for "hidden" Y chromosome in 45,X Turner syndrome ascertained cytogenetically.

Our study confirms the finding that about 85% of X chromosomes in Turner girls are maternally derived. A new observation is the detection of a high frequency of mosaicism (15%) in Turner girls who by cytogenetic analysis were thought to have a pure 45,X karyotype. DNA examination of the material was done by hybridization with digoxigenin labelled, non-radioactive probes, and PCR products for microsatellite analysis were run on polyacrylamide gels. We screened for the presence of "hidden" Y chromosome mosaicism, using the primers SRY, ZFY, DYZ3, DYZ1 and DYS132. Contrary to other reports using the PCR technique to unravel "hidden" Y chromosome mosaics, we did not find any positive cases. A precise technical protocol for these new techniques is given, and the advantages are discussed.

Chromosome Banding↗
PubMed1995

Aerobic exercise capacity at sea level and at altitude in Kenyan boys, junior and senior runners compared with Scandinavian runners.

The aim of this study was to characterize Kenyan runners in regard to their oxygen uptake and blood and ammonia responses when running. Untrained Kenyan boys (14.2 +/- 0.2 years) and Scandinavian runners were included for comparison. The studies were performed at altitude (approximately 2.000 m.a.s.l.) and, for several Kenyan and Scandinavian runners, at sea level as well. At altitude sedentary adolescent Kenyan boys had a mean maximal oxygen uptake (VO2max) of 47 (44-51) ml.kg-1.min-1, whereas similarly aged boys regularly walking or running but not training for competition reached above 62 (58-71) ml.kg-1.min-1 in VO2max. Kenyan runners in active training had 68 +/- 1.4 ml.kg-1.min-1 at altitude and 79.9 +/- 1.4 ml.kg-1.min-1 at sea level, with individuals reaching 85 ml.kg-1.min-1. The best Scandinavian runners were not significantly different from the Kenyan runners in VO2max both at altitude and at sea level, but none of the Scandinavians reached as high individual values as observed for some Kenyan runners. The running efficiency, determined as the oxygen cost at a given running speed, was less in the Kenyan runners, and the difference became more pronounced when body weight was expressed in ml.kg-0.75 min-1. Blood lactate concentration was in general lower in the Kenyan than in the Scandinavian runners, and the Kenyans also had extremely low ammonia accumulation in the blood even at very high exercise intensities. It is concluded that it is the physical activity during childhood, combined with intense training as teenagers that brings about the high VO2max observed in some Kenyan runners. Their high aerobic capacity, as well as their good running economy, makes them such superior runners. In addition, their low blood lactate and ammonia accumulation in blood when running may also be contributing factors.

Adolescent↗
PubMed1995

Morphology, enzyme activities and buffer capacity in leg muscles of Kenyan and Scandinavian runners.

The study comprises data on 12 Scandinavian runners who had either trained for two weeks in Kenya (n = 6; approximately 2000 meters above sea level (m.a.s.l.)) or in Portugal (n = 6; sea level (s.l.)) and on 13 Kenyan runners (9 junior and 4 senior) living and training at approximately 2000 m.a.s.l. Muscle biopsies were taken before and after the training camps in the Scandinavian runners and once on the Kenyan runners from the vastus lateralis (v.l.) and the gastrocnemius muscles. Muscle fiber size and composition were similar in the various groups (4.6-5.1 X 10(3) microns2; ST approximately 60-70%; FTa 30-40%; FTb < 6.0%) with a tendency for some more (approximately 5%) FTa fibers in the gastrocnemius muscle. Mean number of capillaries in v.l. varies between 405-493 cap.(mm2)-1, 2.0-2.7 cap.fiber-1, and 4.4-6.2 cap around the various fiber types, with the Kenyan seniors having the highest and the Kenyan juniors the lowest values. All runners had 10-20% more capillaries in their gastrocnemius muscle. Similar levels for citrate synthase (CS) activity were found in the v.l. of the Kenyan seniors and Scandinavian runners, whereas the Kenyan juniors were 10-15% lower. The 3- hydroxyacyl-CoA-dehydrogenase (HAD) activity was 20% higher in the Kenyan than in the Scandinavian runners. In the gastrocnemius muscle, both enzyme activities were 20-50% higher in Scandinavian and Kenyan runners. The ratio for lactate dehydrogenase (LDH) isoform1-2 and isoform4-5 was increased when training at altitude due to a lowering of LDH4-5 and became close to what was observed in the Kenyan runners.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1991

Mycoplasma hyosynoviae isolation from the upper respiratory tract and tonsils of pigs.

The occurrence of Mycoplasma hyosynoviae at different locations of the upper respiratory tract and tonsils of pigs was investigated in herds with problems of arthritis apparently caused by this microorganism. The isolation of M. hyosynoviae was facilitated by the use of a medium selectively suppressing the growth of Mycoplasma hyorhinis. M. hyosynoviae was cultured from 106 of 178 tonsils of slaughterhouse pigs from 8 herds but could not be isolated from the mucosa of the nasal cavity or the oral-pharyngeal area of 100 living, 10-20 weeks old pigs in 5 of the herds. The value of the selective principles in the medium appears from the circumstance that 86 of the 106 isolates were obtained despite the presence of M. hyorhinis. It is concluded that the tonsil is a reservoir for M. hyosynoviae and is probably the location of choice for an easy demonstration of the presence of this mycoplasma in a pig herd.

Animals↗