C1-esterase inhibitor blocks T lymphocyte proliferation and cytotoxic T lymphocyte generation in vitro

We have previously shown that activated C1s complement and activated T cells cleave beta2-microglobulin (beta2m) in vitro leading to the formation of desLys58 beta2m. This process can specifically be inhibited by C1-esterase inhibitor (C1-inh). Furthermore we showed that exogenously added desLys58 beta2m in nanomolar amounts to a one-way allogenic mixed lymphocyte culture (MLC) increased the endogenous production of IL-2 and the generation of allo-specific cytotoxic T lymphocytes. C1-inh was purified from fresh human plasma and added to human or murine MLC and mitogen-stimulated lymphocyte cultures grown in the presence of complement-inactivated serum. Read-outs were cell proliferation, lymphokine production and development of T cell-mediated cytotoxicity. We found that addition of C1-inh to MLC and mitogen- exposed murine and human lymphocyte cultures inhibited proliferation, the development of allospecific cytotoxic activity, and changed the endogenous production of IL-2, IL-4, IL-10, IL-12 and IFN-gamma. These data clearly demonstrate a regulatory function of C1-inh on T cell- mediated immune functions.      

How to use Chlamydia antibody testing in subfertility patients

Screening for tubal factor subfertility by means of Chlamydia antibody testing (CAT) was introduced into the initial work-up of subfertile couples several years ago. The results reported, however, are heterogeneous, and no uniformity exists in cut-off levels of titres, or in definitions of tubal factor subfertility. We performed a prospective cohort study to evaluate the implications of varying the definitions of tubal pathology and of modifying the cut-off levels on the clinical impact of CAT in predicting tubal factor subfertility. In 227 consecutive patients who attended our fertility clinic, the Chlamydia IgG antibody titre was determined and related to tuboperitoneal abnormalities at laparoscopy as a reference standard. According to received operating characteristic (ROC) curve analysis, a titre of 16 is the optimum cut-off level. Increasing the cut-off level improves specificity and positive likelihood ratio (LR+), at the expense of sensitivity and negative LR (LR-). Changing the definition of tubal factor subfertility from unspecified tuboperitoneal abnormalities into extensive adhesions and/or bilateral distal tubal occlusion improves LR+, LR- and kappa significantly. We conclude that CAT is more accurate in predicting severe distal tubal pathology than unspecified tuboperitoneal abnormalities. Although from a statistical point of view a titre of 16 is the optimum cut-off level, from a clinical point of view 32 or 64 may be preferable, depending on the aim of screening and the inception cohort.      

Neural mechanisms underlying the clasp-knife reflex in the cat. II. Stretch-sensitive muscular-free nerve endings

1. The goal of this study was to determine the contribution of muscular free nerve endings to the clasp-knife reflex by comparing their response properties and reflex actions to the clasp-knife reflex. 2. The responses of single muscle afferents were examined in anesthetized cats using stretch and isometric contraction of ankle extensor muscles identical to those that evoked clasp-knife inhibition in decerebrated and dorsal spinal-hemisectioned cats. 3. Fifty-three stretch-sensitive mechanoreceptor afferents were identified as free nerve ending afferents based on their conduction velocities, location within the muscle, uniformity of response, and dissimilarity to other muscle proprioceptors. The afferent conduction velocities were in both the group III (56%) and group II (44%) range, including five fast-conducting group II afferents (greater than 55 m/s). 4. The stretch response of stretch-sensitive, free nerve endings (SSFNEs) showed several characteristic features: 1) afferents were excited only by large stretches that produced significant passive force; 2) afferent activity began after a brief delay and exhibited segmentation of discharge during ramp stretch, a maximum at the end of ramp stretch, and rapid and complete decay during static stretch, and 3) afferent response adapted to repeated stretches. These properties match those of clasp-knife inhibition described in the companion paper, except that the SSFNE segmentation and maximum were more pronounced and their decay during maintained stretch was more rapid. 5. Isometric contraction produced by electrical stimulation of the muscle nerve, which induced force-evoked inhibition in decerebrated and dorsal hemisectioned cats, also consistently excited SSFNEs. Stretch evoked greater excitation than contraction, indicating that both length and force contribute to SSFNE activity. 6. Stimulation of free nerve endings by squeezing the achilles tendon in cats exhibiting the clasp-knife reflex evoked powerful, homonymous inhibition and a flexion-withdrawal pattern of reflex action--that is, inhibition of extensor and excitation of flexor muscles throughout the hindlimb, which parallels the spatial divergence of the clasp-knife reflex. 7. Intrathecal application of capsaicin, which preferentially blocks the reflex actions of small afferent fibers, blocked clasp-knife inhibition in decerebrated, dorsal hemisectioned cats. 8. The similarities between the reflex actions and response properties of SSFNEs and the properties of the clasp-knife reflex suggest that SSFNEs mediate clasp-knife inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)     

The effect of methotrexate on lipoxygenase metabolism in neutrophils from rats:In vitro andex vivo studies

Studies were undertaken to examine the effect of methotrexate (MTX) administeredin vivo or addedin vitro upon the production of the 5-lipoxygenase (5-LO) metabolites of arachidonic acid (AA) by rat neutrophils. Peptone-induced peritoneal exudate cells were stimulated by A23187 and the cell suspensions assayed for leukotriene B₄ (LTB₄), the all-trans isomers of LTB₄ and 5-hydroxyeicosatetraenoic acid (5-HETE) using high-pressure liquid chromatography. MTX addedin vitro to rat cells was weakly inhibitory; however, no inhibition of LTB₄ production was seen followingin vivo administration of MTX by oral, subcutaneous or intraperitoneal routes. On the basis of these findings, inhibition of 5-LO metabolism does not appear to explain the anti-inflammatory effects of MTX.     

Antiphospholipid antibodies and the outcome of pregnancy after the first in-vitro fertilization and embryo transfer cycle

Increased antiphospholipid antibody prevalence has been demonstrated by a number of recent studies in in-vitro fertilization (IVF) patients but the potential effects of antiphospholipid antibodies on the different components of the reproductive process and the consideration of whether to test IVF patients for antiphospholipid antibodies are controversial. The present study was undertaken to investigate the possible association between the presence of circulating antiphospholipid antibodies (namely the lupus anticoagulant and anticardiolipin antibodies), among a series of 21 consecutive IVF patients having a clinical spontaneous abortion after their first embryo transfer. As a control group (n=42), the nearest IVF cycle resulting in an ongoing pregnancy before and after each miscarried IVF cycle (i.e. the closest cycles in temporal relationship to the index cycle) was used. One patient (4.8%) in the study group and two women (4.8%) among controls were seropositive for antiphospholipid antibodies. These low and similar seropositivity rates found in the two groups studied lead us to conclude that antiphospholipid antibodies testing in IVF patients should be considered only in those women having repeated failures of implantation/clinical abortion after embryo transfer but not in an infertile general population reaching an IVF programme.      

Assessment of bioequivalence after subcutaneous and intramuscular administration of urinary gonadotrophins

The objective was to demonstrate bioequivalence between s.c. and i.m. administration of Humegon (FSH/LH ratio 1:1) and Normegon (FSH/LH ratio 3:1). In two randomized, single-centre, cross-over studies, 18 healthy volunteers on each formulation were assigned to one of the two administration sequences. Subjects were given single doses of one of the above gonadotrophins after endogenous gonadotrophin production had first been suppressed using high-dose oral contraceptive. Subsequently, rate (Cmax, tmax) and extent (AUC) of absorption of follicle stimulating hormone (FSH) and luteinizing hormone (LH) were determined for 14 days. For Cmax and AUC, analysis of variance (ANOVA) was performed on log-transformed data and for tmax ANOVA was performed on ranks. Intramuscular and s.c. injections of Humegon were bioequivalent with respect to the main pharmacokinetic parameters, being AUC and Cmax of FSH absorption. Intramuscular and s.c. injections of Normegon were bioequivalent with respect to the AUC of FSH and not bioequivalent with respect to the Cmax of FSH. For tmax of FSH as well as for most LH variables of both preparations, bioequivalence could not be proven due to the high intra- and interindividual variability and/or concentrations being close to the detection limit. Thus, the main pharmacokinetic FSH variables after i.m. and s.c. administration of Humegon and Normegon were bioequivalent.