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Biomedical subjects

K Larsen

Publications and source records attributed to K Larsen.

At least 73 records · Page 4Linked to original sources
PubMed1994

A protein binding AT-rich sequence in the soybean leghemoglobin c3 promoter is a general cis element that requires proximal DNA elements to stimulate transcription.

A nodule nuclear factor, NAT2, interacts with two AT-rich binding sites (NAT2 BS1 and NAT2 BS2) in the soybean leghemoglobin (lb) c3 promoter. In transgenic Lotus corniculatus nodules, an oligonucleotide containing NAT2 BS1 activated an inactive -159 lbc3 promoter when placed immediately upstream of the promoter. The activation was independent of the orientation of NAT2 BS1 but was dependent on its position in the promoter. The abilities of different mutated binding sites to activate expression in vivo were correlated to their respective in vitro affinities for binding NAT2. This suggested that the interaction between NAT2 and NAT2 BS1 is responsible for the observed reactivation. Further activation experiments with the lbc3 and the leaf-specific Nicotiana plumbaginifolia ribulose bisphosphate carboxylase/oxygenase small subunit (rbcS-8B) promoter suggested that another specific cis element(s) is required for the function of NAT2 BS1. Thus, the -102 lbc3 promoter lacking the organ-specific element (-139 to -102) was not reactivated by the presence of the binding site, and the rbcS-8B promoter required sequences between -312 and -257 to be activated by NAT2 BS1. This implies that NAT2 has to work in combination with other trans-acting factor(s) to increase expression. The finding of NAT2-like binding activities in different plant organs and the specific expression of the hybrid NAT2 BS1/-312 rbcS-8B promoter in leaves suggest that NAT2 is a general activator of transcription.

Arylamine N-Acetyltransferase↗
PubMed1994

Clinical course of patients with primary nasal polyps.

A follow-up study on 180 patients treated for the first time for nasal polyps was performed. The follow-up period was from 1 to 8 years with a median of 57 months. The majority of patients had postoperative topical steroid treatment. 65.6% of patients had one polypectomy, 17.8% had two polypectomies, 10% had 3, 2.8% had 4, and 3.9% of patients had 5-10 polypectomies performed during the follow-up period. Patients without asthma, acute recurrent or chronic sinusitis, acetylsalicylic acid intolerance, or allergy had fewer polypectomies and less topical steroid treatment than patients with these characteristics. The recurrence profile between the first and second polypectomy described with the life-table method showed a slow decline in the number of patients with only one polypectomy. The time span needed before significant clinical symptoms occurred after the first polypectomy indicates that not all primary polyp patients are prone to recurrence. Nasal polyps is probably a manifestation of different clinical and aetio-pathogenetic entities. Further identification of such entities is needed to improve treatment strategy.

Adolescent↗
PubMed1993

Non-reflex and reflex mediated ankle joint stiffness in multiple sclerosis patients with spasticity.

In this study, we have measured the passive, the intrinsic, and the reflex-mediated mechanical response to stretch of the ankle extensors and flexors in 13 spastic multiple sclerosis patients and 10 healthy control subjects. In the ankle flexors, the patients had no reflex-mediated stiffness. The passive stiffness was increased by 138% (95% confidence interval: 26-91%) and the intrinsic stiffness by 79% (41-158%) when compared with the healthy subjects. In the ankle extensors, the reflex-mediated stiffness and the intrinsic stiffness of the patients were equal to the reflex-mediated and the intrinsic stiffness in healthy subjects. The passive stiffness was increased by 152% (41-352%). We conclude that spastic muscles in multiple sclerosis patients have an increased non-reflex stiffness (passive plus intrinsic stiffness), and that the reflex-mediated stiffness in the extensors during a sustained voluntary contraction does not differ significantly from healthy subjects.

Adult↗
PubMed1993

Differential expression within the glutamine synthetase gene family of the model legume Medicago truncatula.

The glutamine synthetase (GS) gene family of Medicago truncatula Gaertn. contains three genes related to cytosolic GS (MtGSa, MtGSb, and MtGSc), although one of these (MtGSc) appears not to be expressed. Sequence analysis suggests that the genes are more highly conserved interspecifically rather than intraspecifically: MtGSa and MtGSb are more similar to their homologs in Medicago sativa and Pisum sativum than to each other. Studies in which gene-specific probes are used show that both MtGSa and MtGSb are induced during symbiotic root nodule development, although not coordinately. MtGSa is the most highly expressed GS gene in nodules but is also expressed to lower extents in a variety of other organs. MtGSb shows higher levels of expression in roots and the photosynthetic cotyledons of seedlings than in nodules or other organs. In roots, both genes are expressed in the absence of an exogenous nitrogen source. However the addition of nitrate leads to a short-term, 2- to 3-fold increase in the abundance of both mRNAs, and the addition of ammonium leads to a 2-fold increase in MtGSb mRNA. The nitrogen supply, therefore, influences the expression of the two genes in roots, but it is clearly not the major effector of their expression. In the discussion section, the expression of the GS gene family of the model legume M. truncatula is compared to those of other leguminous plants.

Ammonia↗
PubMed1992

Recognition of substrates by tyrosylprotein sulfotransferase. Determination of affinity by acidic amino acids near the target sites.

The sulfation of proteins by tyrosylprotein sulfotransferase (TPST) is highly site-specific. In this study, we examined the sequence specificity of the target site for TPST by determining the kinetics of rat liver TPST with peptides related to the sequence of the C4 component of complement. The data obtained from this study demonstrate that selective elimination of negative charges from the -5 to +5 region of the acceptor tyrosine, either by removal or by isosteric substitution or the acidic amino acids in the region, produced a substantial change in the Km value, with relatively little effect on Vmax. Substitutions at -1 and +1 positions increase the Km value by 22- and 4-fold, respectively, whereas removal of the acidic amino acids from the -5, -4, or +4 positions increased the Km values by a factor of 2-4. The effect of elimination of an acidic amino acid on the Km value was constant and specific for its particular position in relation to tyrosine, and the effect of modification of more than one amino acid was multiplicative. This study provides evidence that: 1) acidic residues near tyrosines promote sulfation by increasing the affinity of enzyme-substrate binding and have little effect on catalytic rate; 2) the contribution of each acidic residue to affinity for TPST is independent and varies according to position relative to the acceptor tyrosine; and 3) the enzyme interacts with a segment of at least 4-5 residues on each side of the tyrosine, with the residues on the -1 and +1 positions being the most important determinants. In general, residues on the NH2-terminal side of the tyrosine have a greater effect on affinity for TPST.

Amino Acid Sequence↗
PubMed1992

Marked increase of stroke incidence in men between 1972 and 1990 in Frederiksberg, Denmark.

BACKGROUND AND PURPOSE: Stroke incidence declined until the end of the 1970s in the United States, and the decline continued into the 1980s in Japan. The purpose of this study was to determine possible temporal changes of stroke incidence in a European community. METHODS: A prospective stroke registry was established in the community of Frederiksberg (population, approximately 90,000), Denmark, in the two periods 1972-1974 and 1989-1990. All patients suspected of stroke were clinically evaluated by a neurologist. Only patients with first-ever stroke were included. Complete case ascertainment was ensured by registration of both hospitalized and nonhospitalized patients. Death certificates were also scrutinized. RESULTS: A total of 927 patients with first-ever stroke was recorded. The annual stroke incidence rate per 1,000 increased by 18% from 2.6 in 1972-1974 to 3.1 in 1989-1990 (p < 0.01). This increase was due solely to a 42% increase in men, in whom stroke incidence rose from 2.1 to 3.0 (p < 0.0005). Incidence was unchanged in women at 3.0 and 3.1, respectively. The incidence rates from 1972-1974 were age and sex adjusted to the 1990 population. After adjustment to the Danish population, stroke incidence in Denmark was 2.0 for all, 2.3 for men, and 1.9 for women. In the second study period computed tomography or necropsy was performed in 85% of cases; 2.4/1,000 had cerebral infarction; 0.20/1,000 had intracerebral hemorrhage; and 0.02/1,000 had subarachnoid hemorrhage. CONCLUSIONS: In a period when decline in stroke incidence has stopped in the United States and has continued in Japan, a marked increase of stroke incidence in Danish men was observed.

Aged↗
PubMed1992

Psoriasis treatment with vitamin D derivatives.

The naturally occurring 1,25(OH)2 vitamin D3 and the two synthetic derivatives 1,24(OH)2 vitamin D3 and calcipotriol (Calcipotriol, INN, Calcipotriene, USAN) have a profound effect on keratinocyte proliferation and differentiation. Clinical trials have shown an effect of all three derivatives in psoriasis. The limiting factor for the use of 1,25(OH)2 vitamin D3 is the risk of hypercalcemia, which is 100 to 200 times less for calcipotriol and that may be less also for 1,24(OH)2 vitamin D3. Presently, calcipotriol in an ointment base has been marketed in a number of countries and represents an alternative to treatment with topical glucocorticoids and dithranol.

Calcitriol↗
PubMed1992

The peak flow nasal patency index.

The peak flow nasal patency index (NPI) is the ratio between the nasal and oral peak airflow. This index was found to be a good indicator of nasal patency present in 24 patients following septoplasty and indicated significant improvement postoperatively. The peak flow nasal patency index was also correlated to self-assessment scores of nasal function in each patient. In this latter study, a low index correlated to a high self-assessment score, both of which indicated poor nasal patency. Our studies have shown that the peak flow nasal patency index is a useful measure for determining nasal patency, particularly for defining the results of any applied therapies.

Adolescent↗
PubMed1991

Oxygen regulation of uricase and sucrose synthase synthesis in soybean callus tissue is exerted at the mRNA level.

The effect of lowering oxygen concentration on the expression of nodulin genes in soybean callus tissue devoid of the microsymbiont has been examined. Poly(A)+ RNA was isolated from tissue cultivated in 4% oxygen and in normal atmosphere. Quantitative mRNA hybridization experiments using nodule-specific uricase (Nodulin-35) and sucrose synthase (Nodulin-100) cDNA probes confirmed that the synthesis of the uricase and sucrose synthase is controlled by oxygen at the mRNA level. The steady-state levels of uricase and sucrose synthase mRNA increased significantly (5-6- and 4-fold respectively) when the callus tissue was incubated at reduced oxygen concentration. Concomitant with the increase in mRNA level a 6-fold increase in specific activity of sucrose synthase was observed. Two messengers representing poly-ubiquitin precursors also responded to lowering the oxygen concentration. The increase was about 5-fold at 4% oxygen. No expression at atmospheric oxygen or in response to low oxygen was observed when using cDNA probes for other nodulin genes such as leghemoglobin c3, nodulin-22 and nodulin-44.

Blotting, Northern↗
PubMed1991

Mechanical and electromyographic responses to stretch of the human ankle extensors.

1. During maintained ankle extension with background torques ranging from 0 to 70 N.m, the ankle extensors were stretched by a 5 degree rotation of the ankle joint. Maximal stretch velocity was 170 degrees/s. Regression analysis of simultaneous measurements of total torque and needle and surface electromyograms (EMG) from the soleus and gastrocnemius muscles showed that the soleus muscle generates about two-thirds of the maximal torque (approximately 120 Nm) with the subjects in sitting position. In addition, it was found that there is considerable cross talk between the soleus and gastrocnemius muscles when EMGs are recorded by surface electrodes. 2. The soleus EMG response to stretch began with a "phasic" response (latency 41 +/- 4 ms, mean +/- SD), consisting of two peaks, labeled M1 and M2. The phasic response ended 120-140 ms after stretch onset and was followed by a period of reduced EMG activity, ending at 170-210 ms. After this "silent period," a smaller "tonic" response was seen. The phasic responses of the soleus muscle were much larger than the corresponding responses in the anterior tibial muscle. In contrast, the tonic responses were comparable in the soleus and anterior tibial muscles. 3. The amplitudes of the phasic M1 and M2 responses were independent of the level of the background contraction. This disagrees with the "automatic gain principle," according to which the amplitudes of M1 and M2 should increase proportionally with the background EMG. In contrast to the phasic responses, the amplitude of the tonic EMG response, measured 200-400 ms after stretch onset, followed the automatic gain principle.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[An EDP program for distribution of patients at a surgical department].

A computer programme is described which can undertake automatic distribution of patients referred for elective surgery. The programme ensures coordinated reservation of operation and bed resources. The programme provides copies of admission and operation lists to the departments concerned and, similarly, it writes out distribution lists and summoning letters. The programme provides statistics for use in planning of resources and statistics with waiting lists according to diagnoses and the time of waiting. The programme is protected from illegal employment by unauthorized users as typing of the identity of the user and a personal code word are required. The programme fulfills the requirements to a register made by the supervision of registers concerning registers which contain very sensitive personal information.

Bed Occupancy↗
PubMed1990

Peak flow nasal patency indices in patients operated for nasal obstruction.

In 26 patients undergoing operation for nasal obstruction, nasal and oral peak expiratory and inspiratory flow rates were measured preoperatively and 1 month postoperatively. Peak expiratory and inspiratory flow nasal patency indices were calculated from the ratio between the nasal and oral peak flow rates. Postoperatively, these indices were significantly increased for the total nose and for the preoperatively worse nasal cavity. No significant change was observed for the oral peak flow rates. A significant preoperative difference in nasal patency between the two nasal cavities was eliminated by surgery, as the postoperative peak flow of each nasal cavity reached 80% of the peak flow of the total nose on expiration and close to 50% on inspiration. A good correspondence between the subjective improvement of nasal patency and the increase in peak expiratory and inspiratory flow nasal patency indices was observed for the total nose. These findings show that peak flow nasal patency indices give valuable information pre- and post-operatively in patients undergoing nasal surgery and that the method is simple and easy to perform.

Adolescent↗