Soluble Plasmodium falciparum antigens contain carbohydrate moieties important for immune reactivity.

The importance of carbohydrate moieties for the antigenicity of purified soluble Plasmodium falciparum antigens from the asexual blood stage was tested. Digestion of the soluble antigens with alpha-D-galactosidase clearly affected the ability of the antigen to react with malaria-immune sera from different geographical origins in crossed immunoelectrophoresis and immunoblotting. Antigens of 220, 180, 80, and 74 kilodaltons were affected by the enzyme treatment. Furthermore, the enzyme digestion reduced the ability of the purified soluble antigen to stimulate lymphocytes from malaria-immune donors. The results might have important implications for the strategy of developing a malaria vaccine.     

The vascularization of the hypothalamic-hypophyseal region of the eastern brook trout,Salvelinus fontinalis

The hypophysis of the brook trout is irrigated by blood vessels which originate from the internal carotid arteries. These are: (1) branches of the ventral hypothalamic arteries that give rise to an extensive capillary plexus in the neurohypophysis from which vessels extend into all regions of the adenohypophysis; (2) branches of the caudal hypothalamic artery that irrigate the saccus vasculosus and continue anteriorly to supply the ventral areas of the meta-adenohypophysis; (3) a caudal hypophyseal artery which vascularizes a portion of the meta-adenohypophysis however, this vessel is not always present; (4) a pair of small arteries which supply the peripheral regions of the gland directly from the carotids. Most of the neurosecretory fibers of the preoptic-hypophyseal tract terminate close to capillaries in the neurohypophysis. A few axons extend into meso-adenohypophyseal tissue. It is suggested that the secretory activities of the pro-, meso- and metaadenohypophyses are governed by hypothalamic factors that are chiefly transmitted to the gland cells via the vascular system (indirect control). However, the activity of the meso-adenohypophysis may also be regulated by factors which are transmitted directly to the cells from the endings of neurosecretory fibers which have traversed the neurohypophysis (direct control). The distribution and abundance of neurosecretion in the ventral hypophysis suggest the possibility of storage of hypothalamic products within this region.     

Members of the heat-shock protein 70 family promote cancer cell growth by distinct mechanisms

Whereas the stress-inducible heat-shock protein 70 (Hsp70) has gained plenty of attention as a putative target for tumor therapy, little is known about the role of other Hsp70 proteins in cancer. Here we present the first thorough analysis of the expression and function of the cytosolic Hsp70 proteins in human cancer cells and identify Hsp70-2, a protein essential for spermatogenesis, as an important regulator of cancer cell growth. Targeted knock-down of the individual family members by RNA interference revealed that both Hsp70 and Hsp70-2 were required for cancer cell growth, whereas the survival of tumorigenic as well as nontumorigenic cells depended on Hsc70. Cancer cells depleted for Hsp70 and Hsp70-2 displayed strikingly different morphologies (detached and round vs. flat senescent-like), cell cycle distributions (G2/M vs. G1 arrest) and gene expression profiles. Only Hsp70-2 depletion induced the expression of macrophage inhibitory cytokine-1 that was identified as a target of P53 tumor-suppressor protein and a mediator of the G1 arrest and the senescent phenotype. Importantly, concomitant depletion of Hsp70 and Hsp70-2 had a synergistic antiproliferative effect on cancer cells. Thus, highly homologous Hsp70 proteins bring about nonoverlapping functions essential for cell growth and survival.     

CXCR4 and CCR5 expression on CD4+ T cells in vivo and HIV-1 antigen beta-chemokine production in vitro after treatment with HIV-1 immunogen (REMUNE)

BACKGROUND: The chemokine receptors CXCR4 and CCR5 have been identified as the major coreceptors for HIV-1 on CD4+ cells and macrophages. The natural ligands for these receptors are SDF-1 and the beta-chemokines (MIP-1alpha, MIP-1beta, RANTES), respectively, and are the products of a variety of immune cells, including CD8+ T lymphocytes. STUDY DESIGN/METHODS: We hypothesized that the ability to stimulate the natural ligands for these receptors using an immune based therapy might influence in vivo chemokine receptor expression. RESULTS: In vivo CXCR4 expression remained stable after treatment with an HIV-1 Immunogen (REMUNE), whereas CCR5 expression on CD4+ T cells decreased (p < .05). Furthermore, HIV-1 antigen-specific production of beta-chemokines in vitro was also augmented (P < .05). CONCLUSIONS: These preliminary results suggest that this HIV-1-specific immune-based therapy can stimulate antigen-specific beta-chemokine production in vitro and downregulate CCR5 receptor expression on CD4 cells in vivo.     

Expansion of CD5 - B cells in multiple sclerosis correlates with CD80 (B7-1) expression

The pathogenetic role of autoantibodies in multiple sclerosis (MS) is uncertain. CD5+ B cells commonly produce autoantibodies, but CD5 expression has also been implicated in B-cell tolerance. We studied B-cell subsets, anti-myelin protein antibody-secreting cells in cerebrospinal fluid (CSF) and a panel of serum autoantibodies in patients with clinically isolated syndromes (CIS), suggestive of MS and patients with clinically definite MS (CDMS). Patients with CDMS had a higher percentage of CD5- B cells in CSF than did control subjects (P = 0.02). CIS patients with immunoglobulin G (IgG) oligoclonal bands in CSF or multiple lesions on magnetic resonance imaging (MRI) had a higher percentage of CD5- B cells in CSF than did the remaining CIS patients (P = 0.03). The percentage of CD5- and CD80+ B cells correlated positively and the percentage of CD5+ B cells correlated negatively with the number of CSF cells secreting anti-myelin basic protein (anti-MBP) antibodies. The prevalence of serum autoantibodies was comparable in the three patient groups. We conclude that intrathecal expansion of CD5- B cells appears to be more characteristic in MS patients, and CD5+ B cells may be associated with a lower prevalence of anti-myelin antibody production.     

Faster activation of polymorphonuclear neutrophils in resistant mice during early innate response to Pseudomonas aeruginosa lung infection

Polymorphonuclear neutrophils (PMNs) are crucial for the outcome of Pseudomonas aeruginosa lung infection in patients with cystic fibrosis. We compared PMNs and inflammatory cytokines in the lungs and blood from susceptible BALB/c and resistant C3H/HeN mice 1 and 2 days after intratracheal challenge with alginate embedded P. aeruginosa. These parameters were correlated with the quantitative bacteriology and histopathology of the lungs. After challenge, the content of granulocyte colony-stimulating factor (G-CSF) and macrophage inflammatory protein-2 (MIP-2) was increased in the lungs and the sera and the percentage of PMNs was increased in the blood. However, 2 days after challenge the concentration of G-CSF and MIP-2 was higher in the lungs and sera of BALB/c mice. CD11b expression was higher on the PMNs of the C3H/HeN mice. The expression of CD62L on PMNs of both strains of mice was decreased 1 day after bacterial challenge, whereas the expression was increased after 2 days of challenge on PMNs of C3H/HeN mice only. These changes were accompanied by a more severe lung inflammation in BALB/c mice and faster clearance of the bacteria in C3H/HeN mice. In conclusion, the rapid early bacterial clearance in the lungs of C3H/HeN mice could be explained by faster activation of the PMNs, as indicated by the higher up-regulation of CD11b. The severe lung inflammation in BALB/c mice may be caused by the early higher content of G-CSF in the sera mobilizing PMNs from the bone marrow and the persistent chemotactic gradient provided by MIP-2 in the lungs.     

Improved outcome of chronic Pseudomonas aeruginosa lung infection is associated with induction of a Th1-dominated cytokine response

Repeated challenge with antigen is involved in the pathogenesis of a variety of pulmonary diseases. Patients with cystic fibrosis (CF) experience recurrent pulmonary colonization with Pseudomonas aeruginosa before establishment of chronic lung infection. To mimic recurrent lung infections in CF patients, the lungs of susceptible BALB/c mice were re-infected with P. aeruginosa 14 days after the initial infection. Singly-infected BALB/c mice, as well as non-infected mice, were used as controls. Decreased mortality and milder lung inflammation in re-infected BALB/c mice, as well as a tendency for improved clearance of bacteria, was observed when compared with singly-infected mice. The improved outcome in re-infected mice correlated with changes in CD4 cell numbers. Surface expression of LFA-1 on pulmonary CD4 cells was increased in re-infected compared with singly-infected mice. Moreover, resistance to re-infection was paralleled by a shift towards a Th1-dominated response and increased IL-12 production. No significant increase in serum IgG was observed in the re-infected mice. In conclusion, these results indicate a protective role for a Th1-dominated response, independent of antibody production, in chronic P. aeruginosa lung infection in CF.     

Gentamicin susceptibility in Escherichia coli related to the genetic background: problems with breakpoints

In total, 120 Escherichia coli isolates positive for one of the gentamicin resistance (GEN(R)) genes aac(3)-II, aac(3)-IV or ant(2')-I were tested for gentamicin susceptibility by the agar dilution method. Isolates positive for aac(3)-IV or ant(2')-I had an MIC distribution of 8-64 mg/L, whereas isolates positive for aac(3)-II had MICs of 32 to >512 mg/L, suggesting a relationship between the distribution of MICs and the specific GEN(R) mechanism. The MIC distribution, regardless of the GEN(R) mechanism, was 8 - >512 mg/L, which supports the clinical breakpoint of MIC >4 mg/L suggested by EUCAST and questions the breakpoint recommended by the CLSI (> or =16 mg/L).     

Motor unit recruitment and rate coding in response to fatiguing shoulder abductions and subsequent recovery

The purpose of the present study was to investigate motor unit (MU) recruitment and firing rate, and the MU action potential (MUAP) characteristics of the human supraspinatus muscle during prolonged static contraction and subsequent recovery. Eight female subjects sustained a 30° shoulder abduction, requiring 11–12% of maximal voluntary contraction (MVC), for 30 min. At 10 and 30 min into the recovery period, the shoulder abduction was repeated for 1 min. The rating of perceived exertion for the shoulder region increased to “close to exhaustion” during the prolonged contraction, and the surface electromyography (EMG) recorded from the deltoid and trapezius muscles showed signs of local muscle fatigue. From the supraspinatus muscle, a total of 23,830 MU firings from 265 MUs were identified using needle electrodes. Of the identified MUs, 95% were continuously active during the 8-s recordings, indicating a low degree of MU rotation. The mean (range) MU firing rate was 11.2 (5.7–14.5) Hz, indicating the relative force contribution of individual MUs to be larger than the overall mean shoulder muscle load. The average MU firing rate remained stable throughout the prolonged abduction, although firing rate variability increased in response to fatigue. The average concentric MUAP amplitude increased by 38% from the beginning (0–6 min) to the end (24–29 min) of the contraction period, indicating recruitment of larger MUs in response to fatigue. In contrast, after 10 min of recovery the average MU amplitude was smaller than seen initially in the prolonged contraction, but not different after 30 min, while the MU firing rate was higher during both tests. In conclusion, MU recruitment plays a significant role during fatigue, whereas rate coding has a major priority during recovery. Furthermore, a low degree of MU rotation in combination with a high relative load at the MU level may imply a risk of overloading certain MUs during prolonged contractions. Accepted: 6 June 2000     

Identification of recurrent and novel mutations in the LDL receptor gene in Spanish patients with familial hypercholesterolemia. Mutations in brief no. 135. Online

We used the single strand conformation polymorphism (SSCP) method to investigate 13 apparently unrelated Spanish patients with familial hypercholesterolemia (FH) for mutations in the promoter region and the 18 exons and their flanking intron sequences of the low density lipoprotein (LDL) receptor gene. We found 16 aberrant SSCP patterns, and the underlying mutations were characterized by DNA sequencing. Five novel missense mutations, Q71E, C74G, C95R, C281Y and D679E, and one nonsense mutation, Q133X, were identified. We also found six missense mutations, S156L, D200Y, D200G, E256K, T413K and C646Y, and one stop codon mutation, W(-18)X, that were previously described in patients from other populations. A new frameshift mutation, 2085del19, was found in one patient. We also identified three splicing mutations; two of them are novel mutations, 1706-10G->A and 2390-1G->A, and the other one has been reported recently, 313+1G->C. Four patients were found to carry two different mutations in the same allele: Q71E and 313+1G->C; C95R and D679E; W(-18)X and E256K, and C281Y and 1706-10G->A. Our results demonstrate that there is a broad spectrum of mutations in the LDL receptor gene in the Spanish population.