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J Johansen

Publications and source records attributed to J Johansen.

At least 73 records · Page 4Linked to original sources
PubMed1996

Remodeling of nuclear architecture during the cell cycle in Drosophila embryos.

Little is known about what determines the nuclear matrix or how its reorganization is regulated during mitosis. In this study we report on a monoclonal antibody, mAb2A, which identifies a novel nuclear structure in Drosophila embryos which forms a diffuse meshwork at interphase but which undergoes a striking reorganization into a spindle-like structure during pro- and metaphase. Double labelings with alpha-tubulin and mAb2A antibodies demonstrate that the microtubules of the mitotic apparatus co-localize with this mAb2A labeled structure during metaphase, suggesting it may serve a role in microtubule spindle assembly and/or function during nuclear division. That the mAb2A-labeled nuclear structure is essential for cell division and/or maintenance of nuclear integrity was directly demonstrated by microinjection of mAb2A into early syncytial embryos which resulted in a disintegration of nuclear morphology and perturbation of mitosis.

Animals↗
PubMed1996

Exhaustion of CTL memory and recrudescence of viremia in lymphocytic choriomeningitis virus-infected MHC class II-deficient mice and B cell-deficient mice.

To study the contribution of CD4+ T cells and B cells to antiviral immunity and long term virus control, MHC class II-deficient and B cell-deficient mice were infected with lymphocytic choriomeningitis virus. In class II-deficient mice, which lack CD4+ T cells, the primary CTL response is virtually intact, and the infection is initially controlled in most organ sites including the blood. However, approximately 2 mo postinfection, CTL memory cannot be detected, and recrudescence of viremia to titers as high as seen during the acute phase of the infection is observed. To investigate whether this phenomenon could reflect participation of B cells and/or Abs in long term virus control, similar experiments were performed with mice that do not have mature B cells because of a disrupted membrane exon of the mu chain gene. In these mice, the cell-mediated immune response was slightly delayed, but transient virus control was observed in most mice. However, approximately 3 mo postinfection, blood virus titers were as high as observed during the acute infection, and no CTL memory could be demonstrated. These results indicate that Abs and/or B cells are required for permanent virus control and that in their absence, the virus-specific CTL potential becomes exhausted. Together our results indicate that while CD8+ cells play a dominant role in acute virus control, all three major components of the immune system are required for long term virus control.

Acute Disease↗
PubMed1996

Initial formation and secondary condensation of nerve pathways in the medicinal leech.

Invertebrates have proved to be important experimental systems for examining questions related to growth cone navigation and nerve formation, in large part because of their simpler nervous systems. However, such apparent simplicity can be deceiving because the final stereotyped patterns may be the result of multiple developmental mechanisms and not necessarily the sole consequence of the pathway choices of individual growth cones. We have examined the normal sequence of events that are involved in the formation of the major peripheral nerves in leech embryos by employing (1) an antibody directed against acetylated tubulin to label neurons growing out from the central nervous system, (2) the Lan3-2 antibody to label a specific population of peripheral neurons growing into the central nervous system, and (3) intracellular dye filling of single cells. We found that the mature pattern of nerves was characterized by a pair of large nerve roots, each of which branched into two major tracts. The earliest axonal projections did not, however, establish this pattern definitively. Rather, each of the four nerves initially formed as discrete, roughly parallel tracts without bifurcation, with the final branching pattern of the nerve roots being generated by a secondary condensation. In addition, we found that some of the nerves were pioneered in different ways and by different groups of neurons. One of the nerves was established by central neurons growing peripherally, another by peripheral neurons growing centrally. These results suggest that the formation of common nerves and neuronal pathfinding in the leech involves multiple sets of growth cone guidance strategies and morphogenetic mechanisms that belie its apparent simplicity.

Afferent Pathways↗
PubMed1996

Differential expression of the EF-hand calcium-binding protein calsensin in the central nervous system of hirudinid leeches.

By immunocytochemistry the distribution and developmental expression of the small EF-hand calcium-binding protein calsensin in the peripheral (PNS) and central nervous system (CNS) of the three hirudinid leech species Haemopis, Hirudo, and Macrobdella was compared. Labeling with calsensin-specific antibodies demonstrated that there was a pronounced difference in the distribution of calsensin immunoreactivity in the CNS of these leeches. In Haemopis more than 70 neurons were labeled, whereas the number in Hirudo was 51 and in Macrobdella only 8. Furthermore, the expression of calsensin in identified cells common to all three leech species also differed. Immunoblot analysis indicated that this variability was not likely to be due to multiple proteins or isoforms being recognized by the calsensin antibody. Labeling of embryos in various stages of development shows that the ontogeny of calsensin expression in the CNS is a gradual process with some neurons expressing calsensin immediately after completion of neurogenesis, about one-third of the way through embryogenesis, and others expressing calsensin only postembryonically. In contrast to the variability in the pattern and temporal expression by CNS neurons, the early embryonic calsensin expression in a small subgroup of sensillar PNS neurons was a shared feature by all three leech species. These findings suggest that calsensin may have different functional properties in CNS and PNS neurons.

Animals↗
PubMed1996

Relationship between the in vitro radiosensitivity of skin fibroblasts and the expression of subcutaneous fibrosis, telangiectasia, and skin erythema after radiotherapy.

OBJECTIVE: To investigate if the occurrence of subcutaneous fibrosis after radiotherapy in an unselected group of breast cancer patients is related to cellular radiosensitivity of skin fibroblasts as measured in a clonogenic assay. MATERIALS AND METHODS: An in vitro colony-forming assay of normal fibroblast radiosensitivity was applied to primary skin biopsies from 31 breast cancer patients who received post-mastectomy radiotherapy with large doses per fraction (2.7-3.9 Gy) more than 10 years earlier. Three clinical normal-tissue endpoints were assessed. Two late endpoints, subcutaneous fibrosis and telangiectasia, were evaluated in three treatment fields by a single experienced clinician. In addition, skin erythema had been assessed at the end of treatment by members of the staff and junior staff. From previous analyses of normal tissue response, individual clinical radiosensitivity could be assessed as "excess risk' of each of the three reactions. This was defined as the difference between the actual observed response in the patient and the expected response estimated from individual treatment characteristics in a linear quadratic (LQ) mixture model and, for the two late endpoints, with correction for the follow-up time. This clinical radioresponsiveness was compared with the in vitro radiosensitivity of the skin fibroblasts. To this end, the fractions of colony-forming cells after graded single doses were fitted by an LQ survival curve using non-linear regression from which the surviving fraction at 3.5 Gy (SF3.5) was estimated. Assessment at 3.5 Gy was chosen to reflect the fraction size during clinical radiotherapy. RESULTS: A statistically significant variability of in vitro radiosensitivity between patients could be detected for both SF2 (P = 0.0095) and SF3.5 (P = 0.0008). A significant correlation was observed between SF3.5 and excess risk of fibrosis (rs = -0.46, P = 0.009) while no association was found between fibroblast radiosensitivity and either the occurrence of severe skin telangiectasia or the acute endpoint skin erythema. CONCLUSION: These results suggest that variability in the occurrence of subcutaneous fibrosis, but not telangiectasia or erythema, after radiotherapy is partly accounted for by differences in cellular radiosensitivity of normal skin fibroblasts.

Adult↗
PubMed1995

Filarin, a novel invertebrate intermediate filament protein present in axons and perikarya of developing and mature leech neurons.

The lan 3-8 monoclonal antibody recognizes a 63 kD antigen that is associated with the cytoskeleton in leech neurons. We have used this antibody to clone a novel invertebrate neuronal intermediate filament protein, filarin, by screening an expression vector library. A full-length clone of 2.2 kb identified by the antibody was isolated and sequenced. The protein contains a coiled-coil rod domain typical of the superfamily of intermediate filament proteins flanked by unique N- and C-terminal domains. The highest homology of filarin is to the alternatively spliced squid brain intermediate filament protein (Szaro et al., 1991, J. Biol. Chem. 266:15035-15041), the only other invertebrate neuronal intermediate filament in the data bank. However, apart from extensive homology in the two end regions of the rod domain, the similarity of the two proteins is limited to the general coiled-coil structure of intermediate filaments. Thus, filarin may represent a novel type of invertebrate neuronal intermediate filament protein. Filarin contains the extra 6 heptads characteristic of lamins and of all cytoplasmic invertebrate intermediate filaments analyzed so far. By Northern analysis, it appears that filarin is not alternatively spliced, since only a single transcript of 2.2 kb is recognized by the clone. Using the lan 3-8 antibody to follow its developmental expression, we found that filarin is present in all known neurons in the central and peripheral nervous system.

Amino Acid Sequence↗
PubMed1995

Multiple strategies for directed growth cone extension and navigation of peripheral neurons.

Leeches have a diverse constellation of peripheral neural elements that are challenged to extend growth cones in highly specific ways in a constantly changing embryonic environment. Two major systems are reviewed here. In one, peripheral afferents extend growth cones toward the central nervous system (CNS), forming common pathways, and then segregate into particular tracts within the CNS. A majority of these afferents depend on CNS-derived guidance cues and projections from the CNS to guide their way. However, not all of the nerves are established this way and at least one of the peripheral nerves is likely to be pioneered by sensillar sensory afferents. The distribution of particular antigens (such as the lan3-2 antigen) suggests the identity of molecules involved in homophilic adhesion along common pathways, whereas others (such as the lan4-2 and 3-6 antigens) are candidates for mediating specific pathway choices. In the second system, the myo-organizing Comb cell (C cell) projects multiple growth cones simultaneously along oblique trajectories not influenced by segmental or midline boundaries. Its parallel growth cones exhibit space-filling as well as directional growth and are guided by local cues to extend in discrete phases that are coordinated with the development of the environment. Both systems exhibit highly directed outgrowth orchestrated by a hierarchy of cues, establish patterns of neurites used to direct later migrating cells, and seem to be regulated temporally and spatially by interactions with the embryonic environment. These systems illustrate the strengths of examining neural development in vivo across several levels of analysis.

Animals↗
PubMed1995

Peripheral neurons depend on CNS-derived guidance cues for proper navigation during leech development.

In leech, major nerve pathways are pioneered by CNS neurons and evidence from dye-injection and antibody experiments suggest that they serve as guides for later differentiating neurons. In this study we have directly tested this hypothesis by examining the consequences of CNS ablation on the navigation in the periphery of a well-defined population of afferent sensory neurons. We show that in the absence of CNS-derived axons the axonal growth cones of this population of peripheral neurons extend with little directionality and instead of forming orderly projections, default into forming circular fasciculated pathways with each other. This suggests that CNS-derived guidance cues are absolutely required for the correct navigation of these peripheral sensory neurons.

Animals↗
PubMed1995

Calsensin: a novel calcium-binding protein expressed in a subset of peripheral leech neurons fasciculating in a single axon tract.

The mAb lan3-6 recognizes a cytosolic antigen which is selectively expressed in the growth cones and axons of a small subset of peripheral sensory neurons fasciculating in a single tract common to all hirudinid leeches. We have used this antibody to clone a novel EF-hand calcium-binding protein, calsensin, by screening an expression vector library. A full-length clone of 1.1 kb identified by the antibody was isolated and sequenced. In situ hybridizations with calsensin probes and antibody staining using new polyclonal antisera generated against calsensin sequence demonstrate that calsensin indeed corresponds to the lan3-6 antigen. Calsensin consists of 83 residues with a calculated molecular mass of 9.1 kD that contains two helix-loop-helix domains. The calcium-binding domains are likely to be functional in vivo since a fusion protein derived from the calsensin clone binds 45Ca2+ in vitro. Immunoaffinity purification experiments with the lan3-6 antibody shows that a large 200,000 M(r) protein selectively copurifies with calsensin in two different leech species. These results suggest that calsensin may be functioning as a trigger protein which interacts with the larger protein. These data are consistent with the hypothesis that calsensin may mediate calcium-dependent signal transduction events in the growth cones and axons of this small group of sensory neurons which fasciculate in a single axon tract.

Amino Acid Sequence↗
PubMed1995

Circulating intercellular adhesion molecule-1 (ICAM-1) as an early and sensitive marker for virus-induced T cell activation.

The effect of systemic virus infection on the level of circulating ICAM-1 (cICAM-1) in serum, and the role of virus-activated T cells in this context, were studied using the murine lymphocytic choriomeningitis virus infection as primary model system. A marked virus-induced elevation in cICAM-1 in serum was revealed, the presence of which coincided with the phase of virus-induced T cell activation. However, high levels of cICAM-1 in serum were observed well before maximal T cell activation could be demonstrated. No increase in cICAM-1 was observed in the serum of infected T cell-deficient nude mice, clearly demonstrating that T cells were mandatory. Analysis of MHC class I and MHC class II-deficient mice revealed that either CD4+ or CD8+ T cells alone are sufficient, despite a markedly reduced inflammatory exudate in the former animals. These results indicate that virus-activated T cells induce shedding of ICAM-1 into the circulation, and this parameter may be used as an early and sensitive marker for immune activation.

Animals↗
PubMed1994

[Colonoscopy. In investigation, treatment and control of gastrointestinal diseases].

Colonoscopy is the initial examination for patients with manifest or occult rectal bleeding, inflammatory bowel disease and colorectal polyps. In addition to polypectomy, colonoscopy is useful in decompression of adynamic colonileus and laser palliation of intractable tumours. In adenoma patients controls should be limited to high risk patients, i.e. those with large and multiple tubular adenomas, villous adenomas, multiple hyperplastic polyps (> 30), and first degree relatives of patients with colorectal carcinomas. Control after radical surgical treatment of colorectal cancer is offered during the first two years after the operation and to persons younger than 40 years. The efficacy of control programmes for hereditary nonpolyposis colorectal cancer families have to be evaluated in controlled series. Rectosigmoidoscopies could probably replace some total colonoscopies to examine ulcerative colitis patients for cancer, since cancer usually occurs in the distal colon. Complications are rare after diagnostic and therapeutic colonoscopies, but perforation, bleeding and injury to surrounding organs can be experienced.

Colonoscopy↗
PubMed1994

Specific pathway selection by the early projections of individual peripheral sensory neurons in the embryonic medicinal leech.

In leech, the central annulus of each midbody segment possesses seven pairs of sensilla, which are mixed clusters of primary peripheral sensory neurons that extend their axons into the CNS where they segregate into distinct fascicles. Pathway selection by individual afferent growth cones of sensillar neurons was examined by double labeling using intracellular dye-filling with antibody labeling in early Hirudo medicinalis embryos. The monoclonal antibody Lan3-2 was used because sensillar neuronal tracts are specifically labeled by this antibody. Examining 68 individually filled neurons we found that sensillar neuron growth cones bifurcate within the CNS, that they project long filopodia capable of sampling the local environment, and that all of them appeared to choose a single particular CNS fascicle without apparent retraction or realignment of growth cones. Furthermore, each side of the bifurcating afferent growth cones always chose the same fascicle, implying a specific choice of a distinct labeled pathway. By dye-filling individual central neurons (P-cells), we show that there are centrally projecting axons present at the time sensillar afferents enter the ganglionic primordia and select a particular fascicle, and we confirm that at least the dorsal peripheral nerve is likely to be pioneered by central neurons, not by the peripheral afferents. In the sensillum studied here, we found examples of sensory neurons extending axons into one of all the available fascicles. Thus, an individual embryonic sensillum possesses a heterogeneous population of afferents with respect to the central fascicle chosen. This is consistent with the idea that segregation into distinct axon fascicles may be based upon functional differences between individual afferent neurons. Our findings argue strongly in favor of specific pathway selection by afferents in this system and are consistent with previous suggestions that there exists a hierarchy of cues, including surface glycoconjugates that mediate navigation of the sensillar growth cones and the fasciculation of their axons.

Animals↗
PubMed1994

Evidence for a positive correlation between in vitro radiosensitivity of normal human skin fibroblasts and the occurrence of subcutaneous fibrosis after radiotherapy.

A colony-forming assay of human skin fibroblast radiosensitivity was established in our laboratory and applied to primary skin biopsies from 12 women belonging to an unselected group of patients who received postmastectomy radiotherapy 10-12 years prior to this study. The aim was to investigate the relationship between in vitro radiosensitivity and the occurrence of subcutaneous fibrosis after radiotherapy. Early generations of normal skin fibroblasts in exponential growth were irradiated at room temperature at a high dose-rate to estimate the surviving fraction of colony-forming cells after single doses ranging from 1 to 8 Gy. A linear-quadratic cell survival curve was fitted to the data and from these fits the surviving fraction at 3.5 Gy (SF3.5) was estimated. Replicate experiments of different cell generations were made to validate the assay, and the between-patients variability was significantly larger than the assay variability for both SF2(p = 0.002) and SF3.5 (p = 0.04). Patients were treated in the period 1978-1982 with a dose per fraction between 2.7 and 3.9 Gy, a total of 12 fractions at two fractions per week. They were evaluated with respect to the occurrence of marked subcutaneous fibrosis in a total of 36 independent treatment fields. In each treatment field the total dose and dose per fraction at the relevant dosimetric reference depth as well as the length of follow-up were recorded. A previously derived LQ mixture model was applied to these data in order to determine the probability of marked fibrosis in that particular field. From this probability and the actually observed fibrosis, the excess risk of fibrosis was calculated, and this was averaged over the three treatment fields to obtain a single measure of clinical radiosensitivity. Increasing values of SF3.5 were statistically significantly correlated with decreasing probabilities of developing subcutaneous fibrosis (p = 0.014, Spearman's rank correlation test). Thus, this pilot study has demonstrated a positive correlation between in vivo radiosensitivity and normal skin fibroblasts and the clinical expression of subcutaneous fibrosis.

Breast Neoplasms↗
PubMed1994

The relation between retinopathy and albumin excretion rate in insulin-dependent diabetes mellitus. From the Funen County Epidemiology of Type 1 Diabetes Complications Survey.

In a population-based patient material of 138 insulin-dependent diabetics aged 25-34 years, and with a diabetes onset before 30 years of age, the relation between retinopathy and albumin excretion rate was studied. The prevalence rate of any retinopathy was 59% (81) and of proliferative retinopathy 17% (23). After 10 years' duration of diabetes, the prevalence of any retinopathy increased steeply and reached a maximum of about 90% after more than 20 years. Very few patients had proliferative retinopathy during the first 20 years, followed by a gradual increase in prevalence up to 40-50% after 25 years. Twenty-one percent (29) of the study population was found to have an increased urinary albumin excretion rate. These patients were found to have a statistically significant increase in frequency of retinopathy (p < 0.01) -and in particular of proliferative retinopathy -with increasing levels of urinary albumin excretion. Our results suggest a need for more frequent screening for diabetic retinopathy in diabetic patients with than without increased albumin excretion rate.

Adult↗
PubMed1994

Refraction and retinopathy in diabetic children below 16 years of age.

In a population-based cross-sectional study of insulin-dependent diabetes mellitus, 42 children--with a median age of 11 years (range 7-15 years) and a median duration of diabetes of 4 years (range 1-12 years)--underwent an ophthalmological and a biochemical examination (HbA1c). None of the children had visual loss due to diabetes, and only 4.8% had mild, non-proliferative retinopathy. Using cycloplegic refractioning, we found low degree myopia (less than -2D) in 12% of the patients, whereas non-mydriatic measurements increased the frequency of myopia to 29%. We therefore recommend the use of cycloplegia in refractive evaluations of diabetic children.

Adolescent↗
PubMed1994

Quantitative magnetic resonance for assessment of radiation fibrosis after post-mastectomy radiotherapy.

Subcutaneous fibrosis is a serious complication of post-mastectomy radiotherapy with a pronounced influence on skin conditions, shoulder movement and arm oedema. To establish safer radiotherapy schedules, precise evaluation of the tissue damage is required. A feasibility study was performed to assess the value of calculated relaxation times from magnetic resonance (MR) images for quantitative characterization of different degrees of subcutaneous fibrosis after post-mastectomy radiotherapy. A surface coil was applied to the irradiated area, as well as to unirradiated skin, to obtain appropriate MR coronal slices for acquisition of calculated values using a mixed imaging sequence technique. 14 patients with clinically diagnosed subcutaneous fibrosis were examined, 10 of whom had severe fibrosis. The mean T2 values of the treated and untreated side were 53.0 and 56.7, respectively. A statistically significant decrease of the calculated T2 values on the treated side was observed. No correlation was found between the clinically assessed fibrosis and the calculated relaxation times. The findings indicate that despite a general decrease of T2 calculated values, the large variation in the relaxation times restricts the value of MR, as applied in this study, in differentiating between different degrees of fibrosis in normal tissues after radiotherapy.

Aged↗
PubMed1993

[Thyroid cancer in the county of North Jutland. Diagnosis, treatment and prognosis].

Data concerning 153 patients diagnosed with thyroid cancer during the 15-year period 1976-90 were retrospectively analyzed. Fine needle aspiration was performed in 98 patients. False negative smears occurred in 16.5% of the aspirates, most frequently in the papillary carcinoma group in which 20.5% of the smears contained cystic material. It is conducted, that smears containing cystic material without follicular epithelial cells should not be considered adequate for diagnosis and should always be repeated. The tumors were histologically re-examined. In 14 cases the histological diagnosis was re-classified. The ENT-department of Aalborg Hospital treated 136 of the patients. Unilateral lobectomy was performed in localised, unilateral cases of papillary carcinoma and as a main rule, total thyreoidectomy in all other cases of differentiated carcinoma and in all cases of medullary carcinoma. There were few postoperative complications. Unilateral recurrent nerve paralysis occurred in two percent of the patients. The prognosis of differentiated and medullary carcinoma was good and in accordance with other studies in which total thyreoidectomy has been performed in all cases. The pTNM classification did not correlate well with the actuarial survival.

Adolescent↗