AC/A ratios in myopic and emmetropic Hong Kong children and the effect of timolol§

Purpose: Caucasian children with myopia have elevated response accommodative vergence to accommodation (AC/A) ratios. The purpose of this study was twofold: to determine if response AC/A ratios vary with refractive error and with myopic progression rate in Hong Kong Chinese children, and to determine the effect of beta‐adrenergic antagonism with topical timolol application on AC/A ratios. Methods: Thirty children aged eight to 12 years participated in the study. All refractive errors were corrected with spectacle lenses. Accommodative responses were measured using a Shin‐Nippon autorefractor and concurrent changes in vergence were assessed using a vertical prism and a Howell‐Dwyer card at three metres and 0.33 metre. Accommodative demand was altered using plus or minus two dioptre lenses and lens‐ and distance‐induced response AC/A ratios were calculated. Measurements were repeated 30 minutes after the instillation of topical timolol maleate (0.5 per cent). Results: AC/A ratios appeared higher in progressing myopic children but the difference was not statistically significant. Timolol application reduced accommodative convergence (AC) in the stable myopes (reduction = ‐3 ± 1.14^A) but not in the emmetropes (0.69 ± 0.9^P) or progressing myopes (0.16 ± 0.43^A) and this difference between refractive groups was statistically s ignificant (F^2,27= 3.766; P= 0.036). However, timolol did not produce a significant change in the accommodative response to positive or negative lenses or response AC/A ratios. Conclusions: We did not find that AC/A ratios in myopic Chinese children were elevated and therefore, it is unlikely that elevated AC/A ratios are responsible for the high levels of myopia that occur in Hong Kong. The finding that timolol reduced AC in the stable myopes suggests that the autonomic control of accommodative convergence in these children may be different from that in emmetropic children and those with progressing myopia.     

Antigenic change in a human IgG4-specific CH3 epitope upon binding of a monoclonal antibody against a neighboring IgG4-specific epitope.

Two sets of monoclonal antibodies (mAbs) probably reacting with two different epitopes in the CH3 domain of the human IgG4 molecule were studied. We observed that the commercially available mAb HP 6011 inhibited the antigen binding of the three mutually inhibitable mAbs, 40-A2, 41-E8 and 43-F11 (40-series), made by us. However, the 40-series mAbs, including those with similar affinity such as mAb HP6011, were not able to inhibit mAb HP 6011. When the 40-series mAbs were preincubated with IgG4, the mAb HP 6011 could partially displace these antibodies. This one-way inhibition indicates that upon binding mAb HP 6011 changes the antigenic structure of the IgG4 molecule by disrupting the epitope for the 40-series mAbs. A steric hindrance of this epitope by mAb HP 6011 is more unlikely, since the small Fab fragment of mAb HP 6011 also inhibited the reaction of the 40-series mAbs.     

Activation of guinea pig eosinophil respiratory burst by leukotriene B4: role of protein kinase C

Leukotriene B4 (LTB4) and the protein kinase C activator, 4-beta-phorbol dibutyrate (PDBu), both induced a pronounced and concentration-dependent stimulation of hydrogen peroxide (H2O2) generation by purified guinea pig peritoneal eosinophils in the concentration range 1 nM-1 microM. The LTB4 response was inhibited competitively by the specific LTB4 receptor antagonist, U-75302, with a KB of 25 nM, while the concentration-response curves for both stimuli were shifted rightwards (3.8-fold and 2.8-fold for LTB4 and PDBu, respectively) by the competitive protein kinase C inhibitor, 1-O-hexadecyl-2-O-methylglycerol at a concentration of 300 microM. LTB4 appears, therefore, to induce respiratory burst in eosinophils via a receptor-mediated mechanism involving protein kinase C.     

Analgesie durch intraartikuläres Morphin nach Kniegelenksarthroskopien? Eine doppelblinde,randomisierte Studie mit patientenkontrollierter Analgesie*

Previous studies investigating the peripheral action of locally instilled morphine after arthroscopic knee surgery found evidence for an analgesic effect. Follow-up studies have lead to conflicting results.We used patient-controlled analgesia (PCA) to test the analgesic potency of intraarticular morphine. Methods. Patients undergoing arthroscopic knee surgery under general anaesthesia received, after written informed consent and in double-blind and randomised manner, 1?mg morphine diluted in 10?ml saline either intraarticularly or intravenously at the end of the surgical procedure. A control injection of 10?ml saline was given at the other site. The pain intensity on a visual analogue scale (VAS) and the cumulative morphine consumption were recorded at 1, 2, 3, 4, 6, 8 and 24?h after the end of general anaesthesia. Statistics: Wilcoxon rank sum test with P<0.05. Results. A total of 59?patients were included in the study; 29 received morphine intraarticularly (verum group), 30 intravenously (control group). There was no difference in gender, age, duration of arthroscopy or anaesthesia. There were more than 60% diagnostic arthroscopies in both groups; other types of surgery were comparable, with the exception of cruciate band repair procedures only in the control group. We found no difference in morphine consumption or pain intensity between the two groups throughout the study period. Median overall consumption of morphine after 24?h was 14?mg in the verum group and 15?mg in the control group, with wide interindividual variation. Pain intensities were remarkably low. The peak pain intensity of both groups was found at 1?h postoperatively, with median 16/100 on the VAS in both groups. Blinding was robust. Conclusion. We found no reduction in postoperative morphine supplementation after 1?mg morphine intraarticularly compared to 1?mg intravenously given at the end of knee arthroscopies. There were also no differences in pain intensities on a VAS. We conclude that titration of postoperative pain with a morphine-filled PCA pump was unable to show a difference in analgesic potency between intraarticular and intravenous morphine.     

Functional activities and immunoglobulin variable regions of human and murine monoclonal antibodies specific for the P1.7 PorA protein loop of Neisseria meningitidis

The meningococcal PorA protein is considered a promising vaccine candidate. Although much is understood regarding the structure of PorA proteins, little is known about the structure-function relationships of PorA antibodies. The aim of this study was to compare the functional and molecular characteristics of a human monoclonal antibody (MAb) and three murine MAbs specific for the PorA P1.7 serosubtype. Murine MAbs 207,B-4 (immunoglobulin G2a [IgG2a]) and MN14C11.6 (IgG2a) were both bactericidal and opsonophagocytic for P1.7-expressing meningococci, whereas human MAb SS269 (IgG3) and murine MAb 208,D-5 (IgA) initiated neither effector function. Epitope mapping with synthetic peptides revealed that MAbs 207,B-4 and 208,D-5 recognized the sequence ASGQ, which is the same specificity motif that a previous study had established for SS269 and MN14C11.6. Nucleotide and amino acid sequence analyses of the variable regions of the four MAbs showed that the SS269 V(H) region belonged to the VH3 family and was approximately 70% homologous to those of the murine MAbs which were all from the 7183 family, whereas the SS269 V(L) region belonged to the Vlambda1-b family and was less than 40% homologous to those of the murine MAbs which were all members of the Vkappa1 family. The Fab fragment of SS269 was cloned and expressed in Escherichia coli and was shown by enzyme-linked immunosorbent assay analyses to bind as well as intact SS269 MAb to P1.7,16 serosubtype group B strain 44/76. We conclude that distinct differences exist in the effector function activities and variable region gene sequences of human and murine P1.7-specific MAbs despite their recognition of similar epitopes.     

Demonstration of non-idiotypic variable heavy chain (VH) antigens on human peripheral blood lymphocytes

In this study we have obtained evidence for the expression of Vh-like determinants on unstimulated human T lymphocytes as well as T lymphoblasts. These determinants were detected with antisera raised against isolated VH fragments of a human IgG3 cryoglobulin (KUP). The antisera detect idiotypic, VH subgroup and HV framework determinants and behave as anti-immunoglobulin antibodies when tested against peripheral blood mononuclear cells in immunofluorescence experiments. However, sensitive radiolabelling and immunoprecipitation techniques revealed a certain reactivity against highly purified T lymphocytes. The specificity of these T-cell-reactive antibodies has not been fully established, but the results suggest that the antisera contain antibodies directed at VH fragment-specific antigens or antigens not exposed on native immunoglobulins or isolated heavy chains.     

Lysine 322 in the human IgG3 C(H)2 domain is crucial for antibody dependent complement activation

The classical complement activation cascade of the immune system is initiated by multivalent binding of its first component, C1q, to the Fc region of immunoglobulins in immune complexes. The C1q binding site on mouse IgG2b has been shown to contain the amino acids Glu 318, Lys 320 and Lys 322 in the C(H)2 domain (Duncan, A.R., Winter, G.,1988. The binding site for C1q on IgG. Nature 322 738-740). Identical or closely related motifs are found on all IgGs in all species, and the binding site has therefore been thought to be universal. However, the results from another study indicate that the site is different in human IgG1 molecules (Morgan, A., Jones, N.D., Nesbitt, A.M., et al., 1995. The N-terminal end of the C(H)2 domain of chimeric human IgG1 anti-HLA-DR is necessary for C1q, Fc gamma RI and Fc gamma RIII binding. Immunology 86 319-324). To determine the site(s) responsible for complement activation in anti-NIP-mouse/human IgG3 antibodies, we have mutated amino acids Lys 276, Tyr 278, Asp 280, Glu 318, Lys 320 and Lys 322 in two beta-strands in the C(H)2 domains of human IgG3. In addition, we mutated the Glu 333, which resides in close proximity to the postulated C1q-binding site of mouse IgG2b, as well as Leu 235 in the lower hinge region. All mutants were tested in Antibody Dependent Complement Mediated Lysis (ADCML)(4) assays, where the antigen concentration on target cells was varied and human serum was complement source. Only the mutants that lacked the positively charged side chain of lysine in position 322 showed strong reduction in ADCML, particularly at low antigen density on target cells. Alanine scanning of positions 318 and 320 did not affect ADCML, contrary to what was observed for mouse IgG2b. Neither did a leucine to glutamic acid mutation in position 235 have the effect that has been reported for human IgG1. These results suggest that the complement binding site on human IgG3 molecules is different from that found on mouse IgG2b, and possibly on human IgG1 as well. Thus the contact site may not be conserved.     

Compensation for distal impairments of grasping in adults with hemiparesis

Previous studies have shown that patients with arm and hand paresis following stroke recruit an additional degree of freedom (the trunk) to transport the hand during reaching and use alternative strategies for grasping. The few studies of grasping parameters of the impaired hand have been case studies mainly focusing on describing grasping in the presence of particular impairments such as hemi-neglect or optic ataxia and have not focussed on the role of the trunk in prehension. We hypothesized that the trunk movement not only ensures the transport of the hand to the object, but it also assists in orienting the hand for grasping when distal deficits are present. Nineteen patients with chronic hemiparesis and seven healthy subjects participated in the study. Patients had sustained a stroke of non-traumatic origin 6–82 months previously (31±22 months) and had mild or moderate to severe arm paresis. Using a whole hand grasp, subjects reached and grasped a cylinder (35 mm) that was placed sagittally (T1) or at a 45° angle to the sagittal midline in the ipsilateral workspace (T2), both at about 90% arms length (10 trials per target). Eight infrared emitting diodes were placed on bony landmarks of the hand, arm and trunk and kinematic data were recorded by an optical motion analysis system (Optotrak) for 2–5 s at 120 Hz. Hand position and orientation were recorded by a Fastrack Polhemus system. Our results show that during goal-directed prehension tasks, individuals with hemiparesis oriented the hand more frontally for grasping and used more trunk anterior displacement or rotation to transport the hand to the target compared to healthy subjects. Despite these changes, the major characteristics of reaching and grasping such as grip aperture size, temporal coordination between hand transport and aperture formation and the relative timing of grip aperture were largely preserved. For patients with more severe distal impairments, the amount of trunk displacement was also correlated with a more frontal hand orientation for grasping. Furthermore, in healthy subjects and patients without distal impairments, the trunk movement was mostly related to proximal arm movements while in those with distal impairments, trunk movement was related to both proximal and distal arm movements. Data support the hypothesis that the trunk movement is used to assist both arm transport and hand orientation for grasping when distal deficits are present.     

IgG subclass distribution of anti-Rh,anti-Kell and anti-Duffy antibodies measured by sensitive haemagglutination assays.

The IgG subclass distribution of anti Rh antibodies (anti-D, ''anti-Du'', anti-c, anti-E), anti-Kell and anti-Duffy (anti-Fya) antibodies was measured by two haemagglutination techniques on microtitre plates. The first technique involved rabbit subclass specific antisera which were used to agglutinate red cells previously reacted with the patients'' antibodies at high concentration. The second, which was more sensitive, had an additional step by introducing sheep anti-rabbit antibodies (sandwich technique). By the sensitive sandwich technique we revealed, for anti-D antibodies: IgG1 8/19, IgG3 1/19, IgG1/IgG3 8/19, IgG1/IgG2/IgG3/IgG 41/19, IgG1/IgG4 1/19; for the Du reactive anti-D antibodies: IgG1 1/8, IgG1/IgG3 1/8, IgG1/IgG3/IgG4 6/8; for the anti-E antibodies: IgG1/IgG2/IgG4 2/3, IgG1/IgG2/IgG3/IgG4 1/3; for the anti-c antibodies: IgG1 2/5, IgG3 1/5, IgG1/IgG3 1/5; for the anti-Kell antibodies: IgG1 9/20, IgG1/IgG3 1/20, IgG1/IgG4 8/20, IgG1/IgG3/IgG4 2/20; and for anti-Duffy antibodies: IgG1 1/8, IgG1/IgG4 7/8. These results are partly at variance with previously published results.