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Biomedical subjects

J Johansen

Publications and source records attributed to J Johansen.

At least 37 records · Page 2Linked to original sources
PubMed2000

Reduced [3H]IP3 binding but unchanged IP3 receptor levels in the rat hippocampus CA1 region following transient global ischemia and tolerance induction.

Changes in inositol (1,4,5)-trisphosphate (IP3) binding properties and the protein level of the IP3 receptor have been reported in different pathological conditions in the brain, e.g. cerebral ischemia, Alzheimer's disease, and Huntingtons disease. We used the 4-vessel occlusion model in rat brain to investigate the effect of transient ischemia insults on the IP3 receptor mRNA level, the IP3 receptor protein level and [3H]IP3 binding. Recirculation periods were limited (1-72 h) to avoid the development of delayed neuronal death. We found that the IP3 receptor mRNA levels were decreased after damage-inducing ischemia (9 min) in the hippocampus CA1 and CA3 regions. The mRNA levels were unaltered after tolerance-inducing ischemia (3 min). However, [3H]IP3 binding was significantly reduced after both damage- and tolerance-inducing ischemia in the hippocampus CA1 region. Furthermore, all investigated brain areas showed a decreased [3H]IP3 binding when tolerance-inducing ischemia was followed by a second ischemic insult (3 + 8.5 min ischemia). The IP3 receptor protein levels remained constant in all investigated brain areas. These results indicate that a reduced [3H]IP3 binding capability in the particularly vulnerable areas occurs as an early consequence of cerebral ischemia, before IP3 receptor protein levels are reduced in these areas. Structural or conformational changes altering IP3 binding may be of necessity on the pathway leading to down-regulation of IP3 receptor protein levels, as observed by others.

Adaptation, Physiological↗
PubMed2000

Decision-making models in the analysis of portal films: a clinical pilot study.

Portal films continue to play an important role in the verification of radiotherapy treatment. There is still some discussion, however, as to what action should be taken after a port film has shown a radiation field deviation from the prescribed volume. It was the aim of the present pilot study to investigate the performance of three decision-making models ('Amsterdam', 'Quebec' and 'Newcastle') and an expert panel basing their decision on intuition rather than formal rules after portal film acquisition in a clinical setting. Portal films were acquired on every day during the first week of treatment for five head and neck and five prostate cancer patients (diagnostic phase). If required, the field position was modified according to our normal practice following the recommendation of the expert panel. In order to analyse the results of the models, however, additional port films were taken in the following 3 treatment weeks with the patient moved as required by the different models (intervention phase). The portal films were taken over 4 consecutive days, positioning the patient according to each of the different models on one day each. None of the models diagnosed a field misplacement in the head and neck patients, while the 'Amsterdam' and 'Quebec' models predicted a move in one prostate patient. The 'Newcastle' model, which is based on Hotelling's T2 statistic, proved to be more sensitive and diagnosed a systematic displacement for three prostate patients. The intervention phase confirmed the diagnosis of the model, even if the three portal films taken with the patient position adjusted as required by the model proved to be insufficient to demonstrate an improvement. The 'Newcastle' model does not rely on assumptions about the random movement of patients and requires five portal films before a decision can be reached. This approach lends itself well to incorporation into electronic portal imaging 'packages', where repeated image acquisitions present no logistical difficulty.

Decision Support Techniques↗
PubMed2000

Treatment of morbidity associated with the management of the axilla in breast-conserving therapy.

The purpose of this study was to determine the impact of surgery and radiotherapy on late morbidity associated with the management of the axilla in breast cancer patients. Two hundred and sixty-six patients from a randomized breast conservation trial (DBCG-82TM protocol) were called in for a single follow-up interview and clinical examination of several functional outcome measures after a median of 6.6 years (3.5-10.5). All the patients were treated with lumpectomy and axillary dissection, followed by external beam radiotherapy to the residual breast. High-risk patients were given additional radiation to the regional lymph nodes plus adjuvant systemic treatment. Twenty-eight patients (11%) had arm edema (> or = 2 cm), which was associated with the extent of axillary node dissection as well as with age and radiotherapy (relative risk, RR = 4.5 (1.8-11.2, p = 0.001)). Impaired shoulder movement of any degree (7%) was associated with radiotherapy (RR = 4.0 (1.5-13.8, p = 0.007)) and advanced age (p = 0.002), while the extent of axillary dissection as described by the number of nodes retrieved was the only factor that predicted pain on logistic regression analysis (p = 0.02). A moderate to severe change in arm/shoulder strength and working ability was observed in 7% and 5% of patients, respectively, but no independent predisposing factor was discerned for these endpoints. It is concluded that the level of late functional morbidity several years after breast-conserving treatment is relatively low and clearly relates to age, extension of surgery, irradiation of the axilla or a combination of these factors, depending on the specific clinical outcome measure.

Adult↗
PubMed2000

Fibroblast differentiation in subcutaneous fibrosis after postmastectomy radiotherapy.

In order to acquire a better understanding of the mechanism of radiation-induced fibrosis, we studied the differentiation of normal skin fibroblasts cultured from breast cancer radiotherapy patients with different risk of fibrosis. The differentiation state of fibroblasts was characterized in clonal cultures using established cytomorphological criteria. Collagen synthesis was determined by 3H-proline incorporation into pepsin-resistant protein. Radiation-induced inactivation of fibroblasts was paralleled by an increase in terminally differentiated fibrocytes, demonstrating that premature terminal differentiation is an important response to irradiation of fibroblasts from radiotherapy patients. Surviving colony-forming fibroblasts showed a change in differentiation with an increase in the ratio L:E of progenitor fibroblasts in late (L) compared to early (E) differentiation states. Furthermore, increased collagen production was observed after irradiation. The results provide evidence supporting a role of terminal fibroblast differentiation in radiation-induced fibrosis and imply that the progenitor population surviving radiotherapy might be more prone to terminal differentiation than before radiotherapy.

Breast Neoplasms↗
PubMed2000

Positive and negative interactions of GDNF, NTN and ART in developing sensory neuron subpopulations, and their collaboration with neurotrophins.

Glial cell line-derived neurotrophic factor (GDNF), neurturin (NTN) and neublastin/artemin (ART) are distant members of the transforming growth factor beta family, and have been shown to elicit neurotrophic effects upon several classes of peripheral and central neurons. Limited information from in vitro and expression studies has also substantiated a role for GDNF family ligands in mammalian somatosensory neuron development. Here, we show that although dorsal root ganglion (DRG) sensory neurons express GDNF family receptors embryonically, they do not survive in response to their ligands. The regulation of survival emerges postnatally for all GDNF family ligands. GDNF and NTN support distinct subpopulations that can be separated with respect to their expression of GDNF family receptors, whereas ART supports neurons in populations that are also responsive to GDNF or NTN. Sensory neurons that coexpress GDNF family receptors are medium sized, whereas small-caliber nociceptive cells preferentially express a single receptor. In contrast to brain-derived neurotrophic factor (BDNF)-dependent neurons, embryonic nerve growth factor (NGF)-dependent nociceptive neurons switch dependency to GDNF, NTN and ART postnatally. Neurons that survive in the presence of neurotrophin 3 (NT3) or neurotrophin 4 (NT4), including proprioceptive afferents, Merkel end organs and D-hair afferents, are also supported by GDNF family ligands neonatally, although at postnatal stages they lose their dependency on GDNF and NTN. At late postnatal stages, ART prevents survival elicited by GDNF and NTN. These data provide new insights on the roles of GDNF family ligands in sensory neuron development.

Animals↗
PubMed1999

Differential glycosylation and proteolytical processing of LeechCAM in central and peripheral leech neurons.

LeechCAM is a recently described member of the Ig-superfamily which has five Ig-domains, two FNIII-domains, a transmembrane domain, and a cytoplasmic domain. Phylogenetic analysis indicated that LeechCAM is the leech homolog of apCAM, FasII, and vertebrate NCAM. Using a leechCAM-specific monoclonal antibody we show by immunoblot analysis and by Triton X-114 phase separation experiments that in addition to existing in a transmembrane version LeechCAM is likely to be proteolytically cleaved into a secreted form without the transmembrane domain and the intracellular tail. Furthermore, by immunoprecipitation we demonstrate that LeechCAM is glycosylated with the Laz2-369 glycoepitope, an epitope that has been specifically implicated in regulation of axonal outgrowth and synapse formation.

Animals↗
PubMed1999

Changes in neuropeptide Y receptors and pro-opiomelanocortin in the anorexia (anx/anx) mouse hypothalamus.

The pro-opiomelanocortinergic (POMCergic) system originating in the hypothalamic arcuate nucleus extends projections widely over the brain and has been shown to be intricately linked and parallel to the arcuate neuropeptide Y (NPY) system. Both NPY and POMC-derived peptides (melanocortins) have been strongly implicated in the control of feeding behavior, with the former exerting orexigenic effects and the latter having anorexigenic properties. Mice homozygous for the lethal anorexia (anx) mutation are hypophagic, emaciated, and exhibit anomalous processing of NPY exclusively in the arcuate nucleus, providing an interesting model to study NPY-POMC interactions. In the present study, several morphological markers were used to investigate the histochemistry and morphology of the POMC system in anx/anx mice. In situ hybridization demonstrated decreased numbers of POMC mRNA-expressing neurons in the anx/anx arcuate nucleus. In parallel, mRNA levels for both the NPY Y1 and Y5 receptors, which are expressed in POMC neurons, were decreased. Also, expression of the NPY Y2 autoreceptor was attenuated. Immunohistochemistry using antibodies against adrenocorticotropic hormone to demonstrate POMC cell bodies, against alpha-melanocyte-stimulating hormone to demonstrate axonal projections and against the NPY Y1 receptor to demonstrate dendritic arborizations, showed strikingly decreased immunoreactivities for all these markers. The present data suggest that degeneration of the arcuate POMC system is a feature characteristic of the anx/anx mouse. The possible relationship to the NPYergic phenotype of this animal is discussed.

Adrenocorticotropic Hormone↗
PubMed1999

Antibody identification, chromosome map assignment, and sequence analysis of a Rab escort protein homolog in Drosophila1.

Using a polyclonal antiserum a cDNA encoding a Rab escort protein (REP) homolog in Drosophila has been identified and sequenced. The gene encodes a 511 residue protein with a predicted molecular mass of 56855 Da. Antibody labeling demonstrates that Drosophila REP protein is present in the early embryo and that it is being apportioned uniformly throughout the embryo in a process likely to be linked to the syncytial nuclear divisions. In situ hybridization to polytene chromosomes reveals that the Drosophila REP gene is located in the 56E region on the second chromosome. Drosophila REP is the first invertebrate REP homolog to be identified and characterized.

Alkyl and Aryl Transferases↗
PubMed1999

Molecular cloning and characterization of LKv1, a novel voltage-gated potassium channel in leech.

We have cloned a novel voltage-gated K channel, LKv1, in two species of leech. The properties of LKv1 expressed in transiently transfected HEK293 cells is that of a delayed rectifier current. LKv1 may be a major modulator of excitability in leech neurons, since antibody localization studies show that LKv1 is expressed in the soma and axons of all neurons in both the central and peripheral nervous systems. Comparison of the biophysical and pharmacological properties of LKv1 with native voltage-gated conductances in leech neurons suggests that LKv1 may correspond to the previously characterized delayed rectifier current, I(K). Phylogenetic analysis of LKv1 shows that it is related to the Shaker subfamily of voltage-gated K channels although it occupies a separate branch from that of the monophyletic Shaker clade composed of the flatworm, Aplysia, Drosophila, and mammalian Shaker homologs as well as from that of two recently identified Shaker-related K channels in jellyfish. Thus, this analysis indicates that this group of voltage-gated K channels contains several evolutionarily divergent lineages.

Amino Acid Sequence↗
PubMed1999

Gliarin and macrolin, two novel intermediate filament proteins specifically expressed in sets and subsets of glial cells in leech central nervous system.

Using monoclonal antibodies, we have identified two novel intermediate filament (IF) proteins, Gliarin and Macrolin, which are specifically expressed in the central nervous system of an invertebrate. The two proteins both contain the coiled-coil rod domain typical of the superfamily of IF proteins flanked by unique N- and C-terminal domains. Gliarin was found in all glial cells including macro- and microglial cells, whereas Macrolin was expressed in only a single pair of giant connective glial cells. The identification of Macrolin and Gliarin together with the characterization of the strictly neuronal IF protein Filarin in leech central nervous system demonstrate that multiple neuron- and glial-specific IFs are not unique to the vertebrate nervous system but are also found in invertebrates. Interestingly, phylogenetic analysis based on maximum parsimony indicated that the presence of neuron- and glial cell-specific IFs in coelomate protostomes as well as in vertebrates is not of monophyletic origin, but rather represents convergent evolution and appears to have arisen independently.

Amino Acid Sequence↗
PubMed1999

Is there more than one late radiation proctitis syndrome?

PURPOSE: To investigate the significance of the various late rectal symptoms that appear after radical prostatic irradiation. PATIENTS AND METHODS: Patients with localised prostate cancer treated between 1987 and 1994 at the Mater Hospital, Newcastle with radical megavoltage irradiation were recalled for examination and to complete a detailed questionnaire concerning late radiation-induced symptoms and their effects on normal daily life. The influence of patient age treatment related variables and acute proctitis symptoms occurring during therapy or the late symptoms recorded were assessed and the relationship between late symptoms and late EORTC/RTOG score and impact on normal daily life were studied. RESULTS: The presence of symptoms of acute proctitis was the only factor to predict any of three late symptoms (urgency, frequency and diarrhoea) and late EORTC/RTOG score in this series (odds ratios: 1.7-2.57, P-values: 0.009-0.0007). Cluster and discriminant function analyses revealed the presence of five subgroups of patients with varying permutations of different late rectal symptoms, including one group with minimal symptoms (P < 0.0001). While bleeding and rectal discharge were the major contributors to late EORTC/RTOG score (P < 0.0001 and 0.04), faecal urgency and bleeding were the most important factors to impact on normal daily life (P < 0.0001 and P < 0.0003). A relatively low concordance was found between late EORTC/RTOG score and the patients' self assessment on the effect of their symptoms on their normal daily lives. Some late symptoms, including bleeding and rectal discharge become less prevalent after 3 years of follow-up with a resulting improvement in EORTC/RTOG score. CONCLUSIONS: There may be more than one late (chronic) proctitis syndrome which may be linked in greater or lesser degrees to acute proctitis symptoms occurring during therapy. Urgency is a common late symptom which often has an important impact on normal daily life and deserves recognition in late normal tissue scoring systems. Assessment of the incidence of bleeding as a measure of late rectal morbidity following prostate irradiation may underestimate the impact of these chronic effects. Confirmatory studies are necessary.

Aged↗
PubMed1999

Do acute mucosal reactions lead to consequential late reactions in patients with head and neck cancer?

BACKGROUND AND PURPOSE: The relationship between acute and late mucosal reactions remains ill defined but is of considerable relevance to efforts to produce therapeutic gains through the use of altered fractionation schemes and concurrent chemotherapy. We therefore investigated whether acute mucosal reactions in patients treated with an accelerated and a conventionally fractionated radiotherapy regime predicted the severity of late mucosal reactions. PATIENTS AND METHODS: The study population consisted of 191 patients randomised on a prospective trial comparing conventional fractionation at 2 Gy/fraction per day, 70 Gy over 47 days with an accelerated regimen of 59.4 Gy, 1.8 Gy b.i.d over 24 days for Stage III-IV carcinoma of the head and neck. Acute and late mucosal reactions were scored according to RTOG/EORTC criteria and analyzed using multiple regression techniques. RESULTS: The duration of time spent by patients at the acute confluent mucositis grade 3 level was inversely related to the time to onset of the reaction for both fractionation schedules. Time to onset was more rapid for patients treated on the accelerated schedule but time spent at the reaction grade did not differ significantly between the schedules. After correction for treatment and patient related factors, anatomical site (oral cavity/oropharynx versus hypopharynx/larynx) and increasing duration of confluent mucositis emerged as independent predictors of the hazard of late mucosal reactions with the latter effect being more pronounced in the accelerated treatment arm. The expected reduction in late mucosal effects in the accelerated fractionation arm, predicted by the LQ model for late effects was identified only in patients whose acute confluent mucosal reactions lasted less than 20 days. CONCLUSIONS: The presence of individual patient susceptibility factors that determine the severity of acute mucosal reactions is suggested. A link between severe and prolonged acute reactions and the risk of developing late mucosal reactions that is independent of biological dose, has also been found. Purpose designed prospective studies of these issues are necessary.

Acute Disease↗
PubMed1999

JIL-1: a novel chromosomal tandem kinase implicated in transcriptional regulation in Drosophila.

We have cloned and characterized JIL-1, a novel tandem kinase in Drosophila that associates with the chromosomes throughout the cell cycle. Antibody staining and live imaging of JIL-1-GFP transgenic flies show that JIL-1 localizes to the gene-rich interband regions of larval polytene chromosomes and is upregulated almost 2-fold on the hypertranscribed male X chromosome compared to autosomes. Phylogenetic analysis suggests that JIL-1 together with human MSKs defines a separate family of tandem kinases. That JIL-1 is a functional kinase was demonstrated by autophosphorylation and phosphorylation of histone H3 in vitro. Based on these findings, we propose that JIL-1 may play a role in transcriptional control potentially by regulating chromatin structure.

Amino Acid Sequence↗
PubMed1999

Ku70/80 gene expression and DNA-dependent protein kinase (DNA-PK) activity do not correlate with double-strand break (dsb) repair capacity and cellular radiosensitivity in normal human fibroblasts.

The expression of the Ku70 and Ku80 genes as well as the activity of the DNA-dependent protein kinase (DNA-PK) were studied in 11 normal human fibroblast lines. The proteins studied are known to be part of a double-strand break (dsb) repair complex involved in non-homologous recombination, as was demonstrated for the radiosensitive rodent mutant cell lines of the complementation groups 5-7. The 11 fibroblast lines used in this study represent a typical spectrum of normal human radiosensitivity with the surviving fraction measured for a dose of 3.5 Gy, SF3.5 GY, ranging from 0.03 to 0.28. These differences in cell survival were previously shown to correlate with the number of non-repaired dsbs. We found that the mRNA signal intensities of both Ku70 and Ku80 genes were fairly similar for the 11 cell lines investigated. In addition, the DNA-PK activity determined by the pulldown assay was fairly constant in these fibroblast lines. Despite the correlation between cell survival and dsb repair capacity, there was no correlation between dsb repair capacity and DNA-PK activity in the tested normal human fibroblast lines. Obviously, in this respect, other proteins/pathways appear to be more relevant.

Antigens, Nuclear↗
PubMed1999

Genes involved in animal models of obesity and anorexia.

Pathological deviations in bodyweight is a major increasing health problem in industrialized societies. It is currently unclear what genetic mechanisms are involved in the long-term control of human body-weight and to what extent these genes are involved in pathological deviations of bodyweight control such as anorexia and obesity. Major support for the concept of genetic control of bodyweight has recently emerged from different animal models. A number of new genes have been found during recent years that, when mutated, have a negative effect on bodyweight in animals and sometimes also in man. Although available evidence points toward a multifactorial nature of weight disorders in most human subjects, the single genes isolated in animal models may become powerful tools to elucidate the genetics also in man. In addition, these genes may serve to promote the development of targeted small-drug pharmaceuticals aimed at novel biochemical pathways. Finally, the uncovering of several quantitative trait loci (QTL) influencing body mass, body fat or fat topography in the mouse and rat has now also made it possible to perform studies of polygenically caused obesity in rodents. The role of the Genome Project in developing a complete gene map will greatly facilitate transforming these OTLs to actual molecules involved in the biology of bodyweight.

Adipose Tissue↗
PubMed1999

Insulin treatment for poorly regulated diabetic patients in general practice. Better regulation and symptom relief?

OBJECTIVE: To study the relationship between symptoms, metabolic control and insulin treatment in diabetes mellitus. DESIGN: A cross-sectional questionnaire study of diabetic patients, and a 1-year follow-up study of poorly regulated patients prescribed insulin. Regulation criteria were predefined and the patients acted as their own controls. SETTING: Five primary care practices in Nordland county, Norway. PATIENTS: 111 patients in the cross-sectional study, with 18 of them participating in the follow-up study. MAIN OUTCOME MEASURES: Symptom scores and sum scores, based on five general symptoms--dizziness, depression, fatigue, thirst and dry mouth--and on two urinary symptoms--urinary frequency and urination during the night. RESULTS: Poorly regulated diabetic patients had a higher sum score for general symptoms than better regulated patients (6.1 vs. 4.2, p = 0.078 with Wilcoxon two-sample rank sum test). With parametric analysis, the difference was significant, and remained so when adjusted for age and sex. Females reported more symptoms than males. Symptom relief with insulin was not statistically significant; however, there was a slight but consistent tendency towards less symptoms with better regulation. There was no correlation with HbA1 values at any time during the follow-up study. Only one patient wanted to stop taking insulin after 1 year. CONCLUSION: Better metabolic control and better general well-being seem to be achieved in many cases when poorly regulated patients with type 2 diabetes mellitus begin insulin treatment. The general practitioner should be cautious in promising relief of specific symptoms.

Adult↗
PubMed1999

The fluctuating pattern of various genome types of respiratory syncytial virus in Copenhagen and some other locations in Denmark.

A semi-nested RT-PCR method based on a region of the F and G glycoprotein genes was established, allowing the simultaneous detection and differentiation of group A and group B isolates of respiratory syncytial virus (RSV). The PCR products were subjected to digestion with restriction endonucleases to further differentiate the isolates. Using, in addition, previously reported studies the prevalence of various genome types in the Copenhagen region over a period of 6 years was established. Furthermore, the prevalence of genome types was determined in a distant region in Denmark during the winters of 1996/97 and 1997/98, and in yet another distant region during the winter of 1997/98. It was shown that the different regions in Denmark to a large extent share the same pool of genome types of RSV. Yet, while the fluctuating patterns of the two groups and various genome types were almost identical at different hospitals in the Copenhagen region, they varied between the different regions. This suggests that epidemics in local communities primarily rely on region-specific herd immunity parameters and emerge from strains endemically circulating in these local communities. Group B strains in Copenhagen showed an overall predominance, being predominant in three of the six epidemic seasons studied, and of almost equal predominance in one season.

Child↗