The rate of inactivation of these proteases by AT can increase by up to 1000-fold due to the binding of heparin. Heparin binds to AT via a specific pentasaccharide sulfation sequence contained within the heparin polymer:

GlcNAc/NS(6S)-GlcA-GlcNS(3S,6S)-IdoA(2S)-GlcNS(6S)The conformational change in AT on heparin-binding mediates its inhibition of factor Xa. For thrombin inhibition, however, thrombin must also bind to the heparin polymer at a site proximal to the pentasaccharide. The highly negative charge density of heparin contributes to its very strong electrostatic interaction with thrombin. The formation of a ternary complex between AT, thrombin, and heparin results in the inactivation of thrombin. For this reason, heparins activity against thrombin is size-dependent, with the ternary complex requiring at least 18 saccharide units for efficient formation. In contrast, antifactor Xa activity via AT requires only the pentasaccharide-binding site. This size difference has led to the development of low-molecular-weight heparins (LMWHs) and fondaparinux as anticoagulants. Fondaparinux targets anti-factor Xa activity rather than inhibiting thrombin activity, with the aim of facilitating a more subtle regulation of coagulation and an improved therapeutic index. It is a synthetic pentasaccharide, whose chemical structure is almost identical to the AT binding pentasaccharide sequence that can be found within polymeric heparin and heparan sulfate. With LMWH and fondaparinux, the risk of osteoporosis and heparin-induced thrombocytopenia (HIT) is reduced. Monitoring of the activated partial thromboplastin time is also not required and does not reflect the anticoagulant effect, as APTT is insensitive to alterations in factor Xa.
Kernigs sign
Kernigs sign (after Waldemar Kernig (1840–1917), a Russian neurologist) is positive when the thigh is flexed at the hip and knee at 90 degree angles, and subsequent extension in the knee is painful (leading to resistance). This may indicate subarachnoid hemorrhage or meningitis. Patients may also show opisthotonus—spasm of the whole body that leads to legs and head being bent back and body bowed forward. Brudzinskis signs
Jozef Brudzinski (1874–1917), a Polish pediatrician, is credited with several signs in meningitis. The most commonly used sign (Brudzinskis neck sign) is positive when the forced flexion of the neck elicits a reflex flexion of the hips, with the patient lying supine.Other signs attributed to Brudzinski:
The symphyseal sign, in which pressure on the pubic symphysis leads to abduction of the leg and reflexive hip and knee flexion. The cheek sign, in which pressure on the cheek below the zygoma leads to rising and flexion in the forearm. Brudzinskis reflex, in which passive flexion of one knee into the abdomen leads to involuntary flexion in the opposite leg, and stretching of a limb that was flexed leads to contralateral extension. See also
Meningitis
Meningoencephalitis

References
External links

FPnotebook page on meningeal signs
Image of Kernigs sign