A subpopulation of small pre-B cells in rabbit bone marrow expresses x light chains and exhibits allelic exclusion of b locus allotypes

The expression of immunoglobulin heavy and light chains by pre-B cells and B lymphocytes was examined by two-color immunofluorescence in heterozygous b⁵b⁹ rabbits. Allelic exclusion of b5 and b9 x light chain allotypes was observed for both surface immunoglobulin-negative pre-B cells and surface immunoglobulin-positive B lymphocytes. In newborn bone marrow, pre-B cells and immature B lymphocytes expressing b9 were as numerous as those expressing b5. In contrast, circulating B cells and bone marrow plasma cells expressing the b5 marker outnumber b9⁺ cells by 2 to 1 in adult b⁵b⁹ animals. Whereas most B lymphocytes expressed x light chain b allotypes, approximately 80% of the μ heavy chain-positive pre-B cells did not. The pre-B cells that expressed detectable light chains were relatively small lymphocytes. A model is presented which includes a “transitional” pre-B cell that expresses both p chains and x chains.     

In vivo administration of anti-CD4 monoclonal antibody prolongs survival in longtailed macaques with experimental allergic encephalomyelitis

The in vivo administration of monoclonal antibody (mAb) to the CD4 antigen associated with helper T cells has been successful in prolonging the survival of nonhuman primates with experimental allergic encephalomyelitis (EAE). EAE was induced in 17 outbred longtailed macaques (Macaca fascicularis) by inoculation of homologous myelin basic protein (BP) in complete Freund's adjuvant (CFA). Treatment was begun at the onset of clinical signs. Eleven animals were treated with anti-CD4 mAb Leu3a (eight) or OKT4a (three). Of the six control animals, two received anti-CD8 mAb (Leu2a), and four were treated with saline. Specific T- and B-cell subsets which have been implicated in the development of EAE were monitored throughout the course of the disease by one- and two-color immunofluorescence (IF). The monkey anti-BP antibody and anti-mouse immunoglobulin (IgG) responses were measured by enzyme-linked immunoassay (ELISA) techniques, as were the levels of free-circulating murine IgG. The nature of the infiltrating lymphocytes in the brain was evaluated histologically post mortem. Our results indicate that anti-CD4 mAb can prolong survival and in some cases completely reverse the clinical appearance of the disease; however, relapses did occur. Treatments with Leu3a or OKT4a anti-CD4 mAbs reversed the ongoing depletion of CD4+ and CD8+ cells caused by the development of EAE and appeared to reduce the size and degree of inflammation in brain lesions. These treatments did not induce immunologic tolerance to mouse IgG since all of the anti-CD4-treated animals produced high titers of anti-mouse IgG antibodies. Treatment with Leu2a (anti-CD8) had no effect on the development of EAE. These results suggest that CD4+ cells are important to the pathogenesis of EAE in macaques and that manipulation of this subset with monoclonal antibodies may provide effective treatment of human demyelinating disease.     

Fos-like immunoreactivity in brain regions of domestic rams following exposure to rams or ewes

Limbic and basal forebrain-hypothalamic regions from male sheep differing in sexual performance were quantified for fos-like immunoreactivity. Rams classified as high-sexually performing (HP), low-sexually performing (LP), and male-oriented (MO) received noncontact sensory stimulation from either ewes in estrus (HP, n=5; LP, n=4; MO, n=4) or other males (HP, n=5; LP, n=4; MO, n=5) for a 4-h period on each of 3 consecutive days. Following exposure to stimulus animals on the third day, rams were euthanized and their brains were perfused with a 1% paraformaldehyde/1.5% glutaraldehyde solution and sections were analyzed for fos-like immunoreactivity. Brain regions analyzed were the medial amygdala (meAMY), medial preoptic area (mPOA), bed nucleus of the stria terminalis (BNST), and ventromedial hypothalamic nucleus (VMH). Fos-like immunoreactivity differed between groups in the mPOA and BNST but not in the meAMY or VMH. LP rams exposed to estrous ewes had more (P<.05) neurons staining positive for fos and fos-related antigens (FRA) in the mPOA and BNST than LP rams exposed to other rams or MO rams exposed to either estrous ewes or other rams. Numbers of neurons staining positive for FRA in the mPOA and BNST of LP rams exposed to estrous ewes, however, were not different (P>.05) from HP rams exposed to either estrous ewes or other rams. The similar fos-like immunoreactivity in areas important for the display of sexual behavior in HP and LP rams may reflect similar sensory input in these two groups of rams; however, LP rams, in contrast to HP rams, do not appear to respond similarly to the same sensory stimulus.     

Autoimmune murine thyroiditis. V. Genetic influence on the disease in BSVS and BRVR mice

Two inbred strains of mice, BSVS and BRVR, are similar in their antibody response to thyroglobulin but differ significantly with respect to thyroid gland damage. F₁ hybrids, like BSVS mice, respond well to thyroglobulin, exhibiting extensive thyroid lesions, whereas BRVR mice show minimal thyroid damage. H-2 typing of the two strains showed that BSVS mice have a type similar to H-2^th, with the H-2D-end of H-2^d and the H-2K-end of H-2^s, whereas BRVR mice are H-2^k. The cellular response to thyroglobulin appears to be influenced by a specific immune response gene located near the K-end of the H-2 complex.     

Ca2+–calmodulin-dependent protein kinase expression and signalling in skeletal muscle during exercise

Ca²⁺ signalling is proposed to play an important role in skeletal muscle function during exercise. Here, we examined the expression of multifunctional Ca²⁺–calmodulin-dependent protein kinases (CaMK) in human skeletal muscle and show that CaMKII and CaMKK, but not CaMKI or CaMKIV, are expressed. Furthermore, the effect of exercise duration and intensity on skeletal muscle CaMKII activity and phosphorylation of downstream targets was examined. Eight healthy men exercised at ∼67% of peak pulmonary O₂ uptake     with muscle samples taken at rest and after 1, 10, 30, 60 and 90 min of exercise. Ten other men exercised for three consecutive 10 min bouts at 35%, 60% and 85%     with muscle samples taken at rest, at the end of each interval and 30 min post-exercise. There was a rapid and transient increase in autonomous CaMKII activity and CaMKII phosphorylation at Thr²⁸⁷ in skeletal muscle during exercise. Furthermore, the phosphorylation of phospholamban (PLN) at Thr¹⁷, which was identified as a CaMKII substrate in skeletal muscle, was rapidly (< 1 min) increased by exercise, and remained phosphorylated 5-fold above basal level during 90 min of exercise. The phosphorylation of serum response factor at Ser¹⁰³, a putative CaMKII substrate, was higher after 30 min of exercise. PLN phosphorylation at Thr¹⁷ was higher with increasing exercise intensities. These data indicate that CaMKII is the major multifunctional CaMK in skeletal muscle and its activation occurs rapidly and is sustained during continuous exercise, with the activation being greater during intense exercise.     

A quantitative analysis of the geometry of cat motoneurons innervating neck and shoulder muscles

The geometry of the somata and dendritic trees of motoneurons innervating neck and shoulder muscles was investigated by using intracellular injections of HRP. In general, these motoneurons did not belong to a homogeneous population of motoneurons. Differences in average primary dendritic diameter, number of primary dendrites, and other measures of dendritic tree size were found between different neck and shoulder motoneuron groups. Several indices of proximal dendritic tree size (number of primary dendrites, sum of dendritic diameters, Rall's dendritic trunk parameter, and the sum of dendritic holes) were weakly correlated with the diameter or surface area of the soma. Some of these correlations depended on the muscle supplied by the motoneuron. The total combined dendritic length ranged from 66,660 to 95,390 microns. There was a weak, but positive, correlation between the diameter of primary dendrites and combined dendritic length. This relationship varied from motoneuron to motoneuron. The diameters of all dendrites of three trapezius motoneurons were examined in detail. The total dendritic surface area examined ranged from 415,000 to 488,100 microns 2 and represented approximately 99% of the total neuronal surface area. Last-order dendrites showed a high degree (39.9%) of taper. Dendritic tapering, by itself, was a major factor in the decrease of the (sum of dendritic diameters)3/2 measured at progressively distal sites from the soma. Although few parent and daughter dendrites obeyed the "three-halves law," the average exponent was 1.57. The diameters of primary dendrites and dendritic surface area were weakly correlated. The correlation between dendritic diameter and combined dendritic length or surface area improved if the weighted average of the diameter of second-order dendrites was used as a measure of dendrite size. Second-order dendrites, whose branches terminated in different regions of the spinal cord, showed different relationships between dendritic diameter and combined dendritic length or surface area. Comparisons between the motoneurons examined in the present study and motoneurons innervating other muscles indicate that, although all spinal motoneurons share several common features (e.g., long dendrites, dendritic tapering), each motoneuron group has a set of unique features (e.g., soma shape, relationship between primary dendrite diameter and dendritic surface area). Thus, the rules governing motoneuron dendritic geometry are not fixed but depend on the species of the motoneuron.     

Effects of Feeding Time on Markers of Muscle Metabolic Flexibility Following Acute Aerobic Exercise in Trained Mice Undergoing Time Restricted Feeding

Time-restricted feeding (TRF) is becoming a popular way of eating in physically active populations, despite a lack of research on metabolic and performance outcomes as they relate to the timing of food consumption in relation to the time of exercise. The purpose of this study was to determine if the timing of feeding/fasting after exercise training differently affects muscle metabolic flexibility and response to an acute bout of exercise. Male C57BL/6 mice were randomized to one of three groups for 8 weeks. The control had ad libitum access to food before and after exercise training. TRF-immediate had immediate access to food for 6 h following exercise training and the TRF-delayed group had access to food 5-h post exercise for 6 h. The timing of fasting did not impact performance in a run to fatigue despite TRF groups having lower hindlimb muscle mass. TRF-delayed had lower levels of muscle HSL mRNA expression and lower levels of PGC-1α expression but displayed no changes in electron transport chain enzymes. These results suggest that in young populations consuming a healthy diet and exercising, the timing of fasting may not substantially impact metabolic flexibility and running performance.     

Liver-First Approach for Synchronous Colorectal Metastases: Analysis of 7360 Patients from the LiverMetSurvey Registry

Annals of Surgical Oncology - The liver-first approach in patients with synchronous colorectal liver metastases (CRLM) has gained wide consensus but its role is still to be clarified. We aimed to...