A technique for preparing defined conjugates of horseradish peroxidase and immunoglobulin

Conjugates of horseradish peroxidase (HRP) and sheep anti-human immunoglobulin (anti-Ig) were prepared by means of a heterobifunctional reagent, N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP). The molar ratios of the conjugates could be changed by varying the degree of chemical substitution of anti-Ig and HRP. Gel filtration and affinity chromatography were used to separate conjugated anti-Ig from free HRP and unconjugated anti-Ig. The distribution of complex sizes and the presence of free HRP and anti-Ig in the final products were monitored by sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis. After final purification and characterisation conjugates were studied as reagents in enzyme immunoassays (EIA) with various antigens.Conjugates prepared by SPDP bridging were shown to yield more than 60% of the anti-Ig as conjugated small defined enzyme-protein complexes. A suitably labelled conjugate reacted in a standardised way resulting in a reproducible dose-response curve when a positive serum was assayed in different dilutions.     

Magnetophosphenes: a quantitative analysis of thresholds

Low-frequency and transient magnetic fields of moderate flux densities are known to generate visual phenomena, so-called magnetophosphenes. In the present study, time-variable very low frequency (10–50 Hz) electromagnetic fields of moderate flux density (0–40 mT) were used to induce magnetophosphenes. The threshold values for these phosphenes were determined as a function of the frequency of the magnetic field both in normal subjects and colour defective ones. Maximum sensitivity occurred at a frequency of approximately 20–30 Hz, and with broad-spectrum light the threshold flux density was 10–12 mT. The threshola values were found to be dependent upon the intensity and the spectral distribution of the background light. Sensitivity decreased during dark adaptation. In certain respects deutans differed from subjects with normal colour vision. Possible mechanisms for generation of magnetophosphenes are discussed. The present magnetic threshold curves show a close resemblance to corresponding curves obtained by electric stimulation at various frequencies provided the electric thresholds are divided by the a.c. frequency. These problems are under current investigation in our laboratory. This is in full agreement with the assumption that the fluctuating magnetic field affects retinal neurons by inducing currents which polarise synaptic terminals.     

Temporal expression and cellular origin of CC chemokine receptors CCR1, CCR2 and CCR5 in the central nervous system: insight into mechanisms of MOG-induced EAE

Background  

The CC chemokine receptors CCR1, CCR2 and CCR5 are critical for the recruitment of mononuclear phagocytes to the central nervous system (CNS) in multiple sclerosis (MS) and other neuroinflammatory diseases. Mononuclear phagocytes are effector cells capable of phagocytosing myelin and damaging axons. In this study, we characterize the regional, temporal and cellular expression of CCR1, CCR2 and CCR5 mRNA in the spinal cord of rats with myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis (MOG-EAE). While resembling human MS, this animal model allows unique access to CNS-tissue from various time-points of relapsing neuroinflammation and from various lesional stages: early active, late active, and inactive completely demyelinated lesions.     

Immunizing with mouse trophoblast to obtain mouse-human cross-reacting antibodies against normal and neoplastic human trophoblast

Monoclonal antibodies raised against living, early invasive mouse trophoblast cells were screened on paraffin sections from first- and third-trimester placentas and from hydatidiform moles and choriocarcinoma. Several mouse-human cross-reacting antibodies were recognized, which implies that mouse trophoblast cells can be used as immunogen for producing antibodies against human trophoblast. Among the new antibodies obtained, some were selected for further study. That panel includes a trophoblast specific antibody with capacity to differ between invasive and noninvasive molar tissues, and two antibodies, which detect antigen epitopes in the normal, but not in the neoplastic trophoblast.     

Enhanced local production of complement components in the small intestines of patients with Crohn's disease

There is evidence that complement components may be formed locally in inflammatory lesions containing monocytes and macrophages. To investigate the role of complement in Crohn's disease we measured jejunal-fluid concentrations of the complement components C4, C3, and factor B by perfusion of a closed segment of the jejunum in 22 patients with Crohn's disease thought to be limited to the terminal ileum. The mean (+/- SEM) jejunal-fluid C4 concentration was 2.0 +/- 0.3 mg per liter, significantly higher than the mean level in 35 healthy controls (0.7 +/- 0.1 mg per liter; P less than 0.001). The mean C3 concentration was 1.0 +/- 0.1 mg per liter in the patients and 0.7 +/- 0.1 mg per liter in the controls (P less than 0.05). The factor B levels were similar in the two groups. Calculated rates of intestinal secretion of these components showed differences of the same magnitude. Leakage of protein from plasma was not increased. The jejunal-fluid:serum ratios of these complement proteins indicated that their appearance in the lumen of the jejunum was due to at least in part to local mucosal synthesis. The increased jejunal secretion of C4, but not C3 or factor B, paralleled the clinical activity of Crohn's disease. Values were normal in first-degree relatives of the patients (n = 13), patients with celiac disease (n = 8), and patients with ulcerative colitis (n = 4). We conclude that increased secretion of complement by clinically unaffected jejunal tissue in patients with Crohn's disease reflects the systemic nature of this disorder and may be due to the stimulated synthesis of complement by activated intestinal monocytes and macrophages.     

Intrasplenic immunization with minute amounts of antigen

There are two ways to raise antibodies to minute amounts of immunogen. The first is in-vitro immunization in which the immunogen is presented to a spleen cell culture and about a week later cell fusion for hybridoma production is attempted. The second, and the subject of this review, is intrasplenic immunization, in which the immunogen is deposited into the spleen tissue and the animal itself takes care of growing the spleen cells. Both of these techniques are appropriate when only small amounts of immunogen are available. Intrasplenic immunization, however, requires less laboratory work and there is a decreased risk of contamination, often a problem with hybridoma cultures. The experience of intrasplenic immunization shows that it is the method of choice for immunization with nanogram amounts of immunogen. A successful outcome, however, requires that the immunogen is immobilized on a carrier. This review by Ove Nilsson and Anders Larsson will focus on the various types of matrix which can be used as carriers and on the procedures for transferring these carriers into the spleen tissue.     

The effect of the calcium-entry blocker nifedipine on cold-induced digital vasospasm. A double-blind crossover study versus placebo

The effects of the calcium-entry blocker nifedipine 20 mg, two 10 mg capsules, t.i.d. in patients with cold-induced digital vasospastic disease of idiopathic or traumatic origin was tested in 28 patients, using double-blind crossover technique on both symptoms and test results. The effect of treatment on digital blood pressure during local cooling was assessed using the Nielsen-Lassen method. Symptomatic improvement was reported by 5 patients during placebo treatment and 17 during nifedipine treatment (p less than 0.01). The symptomatic improvement was significant in the total group of patients and in the group of patients with idiopathic vasospastic disease. The digital blood pressure during local cooling improved significantly with nifedipine at 5, 10, 15 (p less than 0.001) and 20 degrees C (p less than 0.05) for the total study population and for the two subgroups except for the change at 20 degrees C in the IDIOP group. At a digital temperature of 10 degrees C, 2 patients reached normal digital blood pressure during placebo treatment compared to 16 during nifedipine treatment (p less than 0.001). The number of side-effects increased significantly (p less than 0.05) during nifedipine treatment. We consider the use of nifedipine in patients with cold-induced digital vasospastic disease to be of great value, especially in patients with digital vasospastic disease of idiopathic origin.     

A dual vulnerability hypothesis for seasonal depression is supported by the seasonal pattern assessment questionnaire in relation to the temperament and character inventory of personality in a general population

BACKGROUND: Personality structure obtained from the psychobiological Temperament and Character Inventory (TCI) was studied in relation to self-reported seasonal variations in mood and behavior measured by the Seasonal Pattern Assessment Questionnaire (SPAQ). METHODS: The subjects comprised 1761 adults (57.6% women) in the age range 35-85 years, enrolled in the Betula prospective random cohort study of Umea, Sweden. RESULTS: Personality profiles of subjects who reported the occurrence of a high degree of seasonal variation as such were associated with a combination of high self-transcendence (ST) and high persistence (PS), irrespective of the level of harm avoidance (HA). Subjects who reported feeling worst in winter were associated with high HA, irrespective of the levels of ST and PS. Also, subjects feeling worst in summer or experiencing overall problems with seasonal variation were associated with high HA in their personality profiles. Using the SPAQ criteria to define seasonal affective disorder (SAD) or subsyndromal SAD (S-SAD), subjects with these disorders often had combinations of high self-transcendence (ST) and high persistence (PS), but with different associations with HA. LIMITATIONS: No evaluations were made for SAD or subsyndromal SAD according to the DSM-IV or ICD 10 criteria. CONCLUSIONS: Our results relating SPAQ with TCI give support for a dual vulnerability hypothesis for seasonal depression proposed in the literature, where it is attributed to a combination of a seasonal factor and a depression factor. Examining the literature regarding the relationships between the different TCI scales and monoamine neurotransmitter functions, those relationships suggest that these two vulnerability factors for seasonal depression may be modulated by different neurotransmitter systems.