Improved survival of Swedish glioblastoma patients treated according to Stupp.

OBJECTIVES: The median survival in glioblastoma (GBM) patients used to be less than 1 year. Surgical removal of the tumor with subsequent concomitant radiation/temozolomide (the Stupp regimen) has been shown to prolong survival. The Stupp protocol was implemented in the county of Jönköping in 2006. The purpose of this study was to examine if the Stupp treatment has prolonged overall survival, in an unselected patient cohort with histologically verified GBM. MATERIAL AND METHOD: This study includes all patients from the county of Jönköping, with a diagnosis of GBM from January 2001 to December 2012. Patients were divided into 2 cohorts, 2001-2005 and 2006-2012, that is before and after implementation of the Stupp regimen. By reviewing the medical case notes, the dates of the histological diagnosis and of death were identified. The median and mean overall survival and Kaplan-Meier survival analysis were calculated and compared between the 2 cohorts. RESULTS: The mean survival was 110 days longer in the cohort treated according to the Stupp regimen. Four patients in the 2006-2012 cohort and 1 patient in the 2001-2005 cohort are still alive. When comparing survival in patients with radical surgery vs biopsy, those that underwent radical surgery survived longer. The significance was slightly greater in the 2001-2005 cohort (mean 163 vs 344 days, P < .001) than in the 2006-2012 cohort (mean 220 vs 397 days, P = .02). CONCLUSION: Survival significantly improved after the implementation of the Stupp regimen in the study region of Sweden.

Anticipating agoraphobic situations: the neural correlates of panic disorder with agoraphobia.

BACKGROUND: Panic disorder with agoraphobia is characterized by panic attacks and anxiety in situations where escape might be difficult. However, neuroimaging studies specifically focusing on agoraphobia are rare. Here we used functional magnetic resonance imaging (fMRI) with disorder-specific stimuli to investigate the neural substrates of agoraphobia. METHOD: We compared the neural activations of 72 patients suffering from panic disorder with agoraphobia with 72 matched healthy control subjects in a 3-T fMRI study. To isolate agoraphobia-specific alterations we tested the effects of the anticipation and perception of an agoraphobia-specific stimulus set. During fMRI, 48 agoraphobia-specific and 48 neutral pictures were randomly presented with and without anticipatory stimulus indicating the content of the subsequent pictures (Westphal paradigm). RESULTS: During the anticipation of agoraphobia-specific pictures, stronger activations were found in the bilateral ventral striatum and left insula in patients compared with controls. There were no group differences during the perception phase of agoraphobia-specific pictures. CONCLUSIONS: This study revealed stronger region-specific activations in patients suffering from panic disorder with agoraphobia in anticipation of agoraphobia-specific stimuli. Patients seem to process these stimuli more intensively based on individual salience. Hyperactivation of the ventral striatum and insula when anticipating agoraphobia-specific situations might be a central neurofunctional correlate of agoraphobia. Knowledge about the neural correlates of anticipatory and perceptual processes regarding agoraphobic situations will help to optimize and evaluate treatments, such as exposure therapy, in patients with panic disorder and agoraphobia.

A new paradigm (Westphal-Paradigm) to study the neural correlates of panic disorder with agoraphobia.

Agoraphobia (with and without panic disorder) is a highly prevalent and disabling anxiety disorder. Its neural complexity can be characterized by specific cues in fMRI studies. Therefore, we developed a fMRI paradigm with agoraphobia-specific stimuli. Pictures of potential agoraphobic situations were generated. Twenty-six patients, suffering from panic disorder and agoraphobia, and 22 healthy controls rated the pictures with respect to arousal, valence, and agoraphobia-related anxiety. The 96 pictures, which discriminated best between groups were chosen, split into two parallel sets and supplemented with matched neutral pictures from the International Affective Picture System. Reliability, criterion, and construct validity of the picture set were determined in a second sample (44 patients, 28 controls). The resulting event-related "Westphal-Paradigm" with cued and uncued pictures was tested in a fMRI pilot study with 16 patients. Internal consistency of the sets was very high; parallelism was given. Positive correlations of picture ratings with Mobility Inventory and Hamilton anxiety scores support construct validity. FMRI data revealed activations in areas associated with the fear circuit including amygdala, insula, and hippocampal areas. Psychometric properties of the Westphal-Paradigm meet necessary quality requirements for further scientific use. The paradigm reliably produces behavioral and fMRI patterns in response to agoraphobia-specific stimuli. To our knowledge, it is the first fMRI paradigm with these properties. This paradigm can be used to further characterize the functional neuroanatomy of panic disorder and agoraphobia and might be useful to contribute data to the differentiation of panic disorder and agoraphobia as related, but conceptually different clinical disorders.

[Haemostaseologic effects of fractionated snake venoms]. / Wirkungen von Schlangengiftfraktionen auf das Gerinnungssystem.

Comparative investigation concerning gelfiltration as well as haemostaseologic analysis of venoms and venom fractions of some snakes (elapidae and viperidae) have shown that in elapidae an inhibition of coagulation is dominant whilst in viperidae the stimulation of coagulation is of importance. Our investigations produce a basis to select substances for activation of coagulation and substances for inhibition of coagulation. Under pharmacological viewpoints the data may produce information to use snake fractions for anticoagulation or for procoagulant therapy in bleeding tendency.

Quantitative proton magnetic resonance spectroscopy of the normal liver and malignant hepatic lesions at 3.0 Tesla.

This comparative study of tumour patients and volunteers aimed at differentiating liver parenchyma from neoplastic lesions by using localised (1)H MRS at 3.0 T as an adjunct to MRI. In total 186 single-voxel proton spectra of the liver were acquired at 3.0 T using the body transmit receive coil. Consecutive stacks of breath-hold spectra were acquired in the PRESS technique at a short echo time of 35 ms and a repetition time of 2,000 ms. Processing of the spectra included spectral alignment with the software package SAGE and quantitative processing with LCModel. The resulting metabolite concentrations were presented in arbitrary units relative to the internal water. In general, the spectra showed four main groups of resonances originating from the methyl protons (0.8-1.1 ppm) and methylene protons of the lipids (1.1-1.5 ppm; 2.0-2.2 ppm) as well as the methyl protons of choline-containing compounds (CCC) at 3.2 ppm. Overall, the CCC and lipid values in malignant liver tumours showed no significant differences to liver parenchyma. On average, total lipid measurements in normal liver parenchyma increased with age, while those of the CCC did not show pertinent changes. Significant differences between the contents of CCC in malignant liver tumours and normal liver parenchyma were not observed, because in patients and volunteers normal liver tissue showed a large variability in the content of CCC.

Magnetic resonance imaging of the cranial nerves in the posterior fossa: a comparative study of t2-weighted spin-echo sequences at 1.5 and 3.0 tesla.

BACKGROUND: High-field magnetic resonance imaging (MRI) at 3.0 Tesla (T) is rapidly gaining clinical acceptance. Whether doubling of the field strength of 1.5T and the subsequent increase in signal-to-noise ratio (SNR) leads to a significant improvement of image quality is not automatically given. PURPOSE: To evaluate the depiction of fine anatomic detail in the posterior fossa, focusing on brain nerves, on T2-weighted imaging, and to define the potential advantage of imaging at 3.0T versus 1.5T. MATERIAL AND METHODS: In total, 10 brainstem nerve pairs of 12 volunteers were identified on T2-weighted MR images of 2- and 5-mm section thickness acquired at 1.5T and 3.0T. The MR images were compared for each subject at both field strengths by three independent readers who rated image quality according to depiction of anatomic detail and contrast by using a rating scale. RESULTS: In general, MR images at 3.0T were considered more conspicuous and less noisy than images at 1.5T. The SNR value measured was almost doubled. With respect to structural identification and contrast according to the rating scale, observer scores were significantly improved both for standard imaging with 5-mm sections and high-resolution imaging with 2-mm sections at 3.0T. Direct comparison revealed a significant increase for evaluated image quality criteria and the number of nerves detected. CONCLUSION: The comparison revealed a clear advantage in favor of T2-weighted MRI at 3.0T vs. 1.5T in depicting the roots and course of brain nerves in the posterior fossa.

Effectiveness of open and arthroscopic rotator cuff repair (UKUFF): a randomised controlled trial.

AIMS: The appropriate management for patients with a degenerative tear of the rotator cuff remains controversial, but operative treatment, particularly arthroscopic surgery, is increasingly being used. Our aim in this paper was to compare the effectiveness of arthroscopic with open repair of the rotator cuff. PATIENTS AND METHODS: A total of 273 patients were recruited to a randomised comparison trial (136 to arthroscopic surgery and 137 to open surgery) from 19 teaching and general hospitals in the United Kingdom. The surgeons used their usual preferred method of repair. The Oxford Shoulder Score (OSS), two years post-operatively, was the primary outcome measure. Imaging of the shoulder was performed at one year after surgery. The trial is registered with Current Controlled Trials, ISRCTN97804283. RESULTS: The mean OSS improved from 26.3 (standard deviation (sd) 8.2) at baseline, to 41.7 (sd 7.9) two years post-operatively for arthroscopic surgery and from 25.0 (sd 8.0) to 41.5 (sd 7.9) for open surgery. Intention-to-treat (ITT) analysis showed no statistical difference between the groups at two years (difference in OSS score -0.76; 95% confidence interval (CI) -2.75 to 1.22; p = 0.452). The confidence interval excluded the pre-determined clinically important difference in the OSS of three points. The rate of re-tear was not significantly different between the two groups (46.4% for arthroscopic and 38.6% for open surgery; 95% CI -6.9 to 25.8; p = 0.256). Healed repairs had the most improved OSS. These findings were the same when analysed per-protocol. CONCLUSION: There is no evidence of difference in effectiveness between open and arthroscopic repair of rotator cuff tears. The rate of re-tear is high in both groups, for all sizes of tear and ages and this adversely affects the outcome. Cite this article: Bone Joint J 2017;99-B:107-15.

Embolization of experimental wide-necked aneurysms with iodine-containing polyvinyl alcohol solubilized in a low-angiotoxicity solvent.

BACKGROUND AND PURPOSE: To evaluate the ready-to-use iodine-containing polyvinyl alcohol (I-PVA) dissolved in the low angiotoxic solvent N-methyl pyrrolidone (NMP) for embolization of porcine wide-necked aneurysms. METHODS: Fourteen broad-based carotid sidewall aneurysms were surgically constructed in 7 swine. I-PVA (40%) in NMP was injected under temporary balloon occlusion bridging the aneurysm neck. After 4 weeks, follow-up angiography, multisection CT angiography (MSCTA), and 3T MR imaging including MR angiography (MRA) sequences were performed. Afterward, harvested aneurysms were investigated histopathologically. RESULTS: The liquid embolic was well visible under fluoroscopy and displayed a favorable precipitation pattern, allowing for controlled polymer delivery. Ten aneurysms (71%) were initially completely occluded, whereas in 1 aneurysm, a minimal polymer leakage was observed. The other 4 aneurysms (29%) were almost completely occluded. One animal suffered a lethal rebleeding from the anastomosis after uneventful embolization. Aneurysms embolized with I-PVA could be discriminated well from the parent artery without beam-hardening artifacts on MSCTA, and no susceptibility artifacts were encountered on MR imaging. Histologic examination revealed all aneurysms covered with a membrane of fibroblasts and an endothelial cell layer while a moderate intraaneurysmal inflammatory response to the polymer was observed. CONCLUSION: I-PVA dissolved in NMP has proved its effectiveness for the embolization of experimental wide-necked aneurysms. This precipitating liquid embolic offers several interesting features in that it needs no preparation before use and no radiopaque admixtures, the latter allowing for artifact-free evaluation of treated aneurysms with MSCTA and MRA. Moreover, it uses NMP as a solvent, which has only a low angiotoxicity.

[Mutation in factor II and factor V gene in patients with peripheral arterial occlusive disease]. / Chronisch-arterielle Verschlusskrankheit der Beine im Stadium IIb-IV: Molekulargenetische Diagnostik von Mutationen im Faktor-II-und Faktor-V-Gen.

Mutations in factor-V- and factor-II-genes are correlated with an increased risk for venous thrombosis according to the literature. The significance of the mutations in factor- II- and factor-V-genes for the development of the peripheral arterial occlusive disease is not known. Therefore, we investigated the presence of these mutations in 152 patients with documented peripheral arterial occlusive disease and 318 controls without peripheral arterial occlusive disease with polymerase chain reaction (PCR). There was no association between factor-II-mutation and peripheral arterial occlusive disease. The factor-V-mutation, however, was increased in patients with peripheral arterial occlusive disease double fold (12 positive cases in 318 controls, 12 positive cases in 152 patients with peripheral arterial occlusive disease). The significance level was reached (p = 0.05) in statistical analysis but the result did not fall below the significance level as necessary to reach statistical significance (odds ratio 2.19). Nevertheless, from these data we have to discuss a biological relevance of factor-V-mutation in the pathogenesis of peripheral arterial occlusive disease.

Novel putative saposin-like proteins of Entamoeba histolytica different from amoebapores.

Amoebapores, the pore-forming proteins of Entamoeba histolytica, have been shown to play a pivotal role in the pathogenicity of the protozoan parasite. They belong to the functionally diverse family of saposin-like proteins (SAPLIPs) characterized by a conserved pattern of cysteine residues and the ability to interact with lipids. Here, we report the identification of genomic sequences encoding presumably novel SAPLIPs in E. histolytica and classify them in the structural and functional context provided by known family members. The genes of altogether 15 SAPLIPs are transcribed in the axenically cultured trophozoites as evidenced by reverse transcriptase-polymerase chain reaction. Interestingly, a remarkable sequence variety with a strong resemblance to that of known, functionally diverse SAPLIPs is present in this archaic, unicellular organism.

[The effect of the field strength on standardized MRI of the brain to demonstrate cranial nerves and vessels: a comparison of 1.5 and 3.0 Tesla]. / Auswirkung der Feldstärke bei der standardisierten Kernspintomographie des Gehirns am Beispiel der Darstellung von Hirnnerven und Gefässen in den basalen Zisternen: Vergleich zwischen 1.5 und 3.0 Tesla.

PURPOSE: Comparison of MR images acquired as routine examinations at a field strength of 3.0 T and 1.5 T to determine whether and to which degree the image quality improves at the higher field strength of 3.0 T. MATERIALS AND METHODS: Routine MR images of 200 patients were examined retrospectively, with 100 images obtained at 1.5 T and 100 obtained at 3.0 T. The examinations were performed with a quadrature head coil and focused on the basal cisterns because of the abundance of small distinct structures in this region. We selected the T2-weighted 2D-FSE sequence in transverse direction for comparison. At both field strengths, the same section thickness of 5 mm and a matrix of 512 x 388 (FOV: 220 mm) were used. The quality of the images was evaluated with regard to depicting the cranial nerves N. III, V - X, the AICA and PICA. For comparison, image quality was rated with a score from 1 (well defined) to 5 (not depicted). RESULTS: A score of 1 was obtained in 46 % of the anatomic structures examined at 3.0 T and in only 9.2 % at 1.5 T. A score of 2 was given in 27.6 % of the anatomic structures at 3.0 T vs. 23.5 % at 1.5 T, a score of 3 in 17.2 % vs. 28.1 %, a score of 4 in 8.6 % vs. 28.7 %, and a score of 5 in 0.4 % vs. 10.3 %, respectively. The Mann-Whitney U test showed significance at p < 0.001 for the comparison of images at 1.5 and 3.0 Tesla. CONCLUSION: Routine magnetic resonance imaging using the same quadrature coil technique and similar acquisition times at 3.0 T and 1.5 T shows an improvement for T2-weighted images at the higher field strength.

The effect of acetazolamide on regional cerebral blood oxygenation at rest and under stimulation as assessed by MRI.

The sensitivity of gradient echo magnetic resonance imaging (MRI) to changes in cerebral blood oxygenation (CBO) has been introduced for mapping functional brain activation. Here, we report that this approach allows monitoring autoregulation in the human brain under vasodilatory stress. Following the administration of acetazolamide, signal intensities of deoxyhemoglobin-sensitive images increased in cortical and subcortical gray matter and to a lesser extent in white matter. This result reflects a venous hyperoxygenation stemming from an increase in cerebral perfusion with oxygen consumption remaining constant. In addition, pharmacologic induction of vasodilation attenuated activity-related MRI signal changes in the visual cortex under photic stimulation. Although intersubject variability was high, this finding indicates individually persisting autoregulatory responsiveness to functional challenge despite an "exhausted" reserve capacity. It is suggested that recording CBO by MRI will foster our understanding of modulation of vasomotor tone and cerebral perfusion. Furthermore, this technique may prove valuable for assessing the cerebrovascular reserve capacity in patients with carotid artery occlusive disease.

Two novel calcium-binding proteins from cytoplasmic granules of the protozoan parasite Entamoeba histolytica.

We report on the molecular characterisation of two novel granule proteins of the protozoon and human pathogen Entamoeba histolytica. The proteins, which were named grainin 1 and 2, show a considerable structural similarity to calcium-binding proteins, particularly within EF-hand motifs. Each grainin possesses three of these putative calcium-binding sites. Based on careful inspection of known structures of protein families containing EF-hands, a domain of grainin 1 covering two EF-hand motifs was modeled by homology. Calcium-binding activity of grainins was demonstrated by two independent methods. These granule proteins may be implicated in functions vital for the primitive phagocyte and destructive parasite such as control of endocytotic pathways and granule discharge.

Enhanced effective fibrinolysis following the neutralization of heparin in open heart surgery increases the risk of post-surgical bleeding.

The tissue-type plasminogen activator related fibrinolytic system was studied in 24 patients undergoing cardiopulmonary bypass surgery. The degradation of fibrinogen and fibrin was followed during and after surgery by means of new sensitive and specific assays and the changes were related to the blood loss measured in the chest tube drain during the first 24 postoperative hours. Although tissue-type plasminogen activator was significantly released into the circulation during the period of extracorporeal circulation (p less than 0.01), constantly low levels of fibrinogen degradation products indicated that a systemic generation of plasmin could be controlled by the naturally occurring inhibitors. Following extracorporeal circulation heparin was neutralized by protamine chloride, and in relation to the subsequent generation of fibrin, there was a short period with increased concentrations of fibrinogen degradation products (p less than 0.01) and a prolonged period of degradation of cross-linked fibrin, as detected by increased concentrations of D-Dimer until 24 h after surgery (p less than 0.01). Patients with a higher than the median blood loss (520 ml) in the chest tube drain had a significantly higher increase of D-Dimer than patients with a lower than the median blood loss (p less than 0.05). We conclude that the incorporation of tissue-type plasminogen activator into fibrin and the in situ activation of plasminogen enhance local fibrinolysis, thereby increasing the risk of bleeding in patients undergoing open heart surgery.

Multicentric evaluation of a new assay for prothrombin fragment F1+2 determination.

A multicenter study of a recently developed ELISA for the determination of prothrombin fragment F1+2 was performed in order to evaluate analytical and clinical aspects. Mean intra-assay and inter-assay reproducibility were found to be 11.0 and 12.6%, respectively. The measuring range covered by the calibration curve reaches from 0.04 to 10.0 nM/l F1+2. Testing 133 healthy subjects a reference range of 0.37 to 1.11 nM/l F1+2 (2.5-97.5 percentile) with a median of 0.66 nM/l F1+2 was calculated. Minor difficulties with blood sampling (venous occlusion for 2 min) did not affect F1+2 plasma concentrations. Significantly increased F1+2 levels were measured in patients with leukemia (p < 0.0001), severe liver disease (p < 0.005) and after myocardial infarction (p < 0.01). Elevated F1+2 concentration before the beginning of heparin therapy (1.25 nM/l) decreased to 0.77 nM/l (p < 0.0001) after 1 day of therapy. For patients in the stable phase of oral anticoagulant therapy decreasing F1+2 concentrations were measured with increasing INR. F1+2 levels were already significantly reduced in patients with INR < 2.0 (0.56 nM/l; p = 0.0005). Thus F1+2 determination may be helpful in identifying activation processes as well as in monitoring anticoagulant therapy.

Treatment of patients with peripheral arterial occlusive disease Fontaine stage IV with intravenous iloprost and PGE1: a randomized open controlled study.

In a randomized open controlled study the clinical effects and tolerability of prostaglandin E1 (PGE1) and the stable prostacyclin (PGI2) analogue, iloprost in the management of diabetic and non-diabetic patients with advanced peripheral arterial occlusive disease (PAOD Fontaine stage IV) were compared. 267 patients were enrolled in this multicentre study and treated for 21-28 days, either by daily infusions of 6 h with iloprost or 2 x 2 h with PGE1. At the end of treatment patients were assessed for evidence of improvement of trophic lesions, relief of rest pain and change of global clinical status. 228 patients were considered as evaluable for efficacy analysis, which revealed 52.7% responders in the iloprost group and 43.1% for PGE1 (p = 0.148). Whereas iloprost showed similar effects in diabetics and non-diabetics (53.3% and 51.4% response rates, respectively), the diabetics treated with PGE1 had a considerably poorer outcome (36.6% versus 53.3%). At 6 months follow-up 62.2% of patients in both groups were alive with a viable limb. Slightly more iloprost patients underwent major amputation (32.1% versus 27.2%), but the number of deaths was reduced by 50% in the iloprost group compared to the PGE1 group (7.5% versus 14.6%, p = 0.10). Side-effects such as headache, flushing and gastrointestinal symptoms were significantly more common in the iloprost group (73.9%) than in the PGE1 group (31.0%), particularly during the first 3 days of dose titration. No specific toxic or unexpected reactions were reported in either group.

Philadelphia chromosome (Ph) positive chronic myelocytic leukemia (CML): frequency of additional findings.

This article documents the cytogenetic findings in 79 patients with typical Ph-positive chronic myelocytic leukemia (CML). Direct preparations of bone marrow and/or peripheral blood of 46 males and 33 females were studied with different banding techniques. Seventy patients were studied during chronic phase. Three (4.3%) had unusual or complex translocations: t(6;22)(p21;q11), t(8;12;9;22)(p21;q21;q34;q11), and t(9;11;22)(q34;q13;q11). One (1.4%) had a +Ph, 1 (1.4%) had a +8, 1 (1.4%) had a del(3)(p13,p23), and 4 of 30 males (13.3%) showed loss of Y chromosome. Five of 8 cases studied during blast crisis had additional abnormalities. The +8 occurred in 4 cases, +10 and +19 each in 3 cases, +6, + 9q+, and +13 each in 2 cases, and +5, +11, +14, +21, +Ph, i(17q), dic(1;9), and structural abnormalities of chromosomes #1, #5, #12, and #13 each in 1 case. Two cases studied in blast crisis alone had complex translocations leading to the Ph. Because it cannot be ruled out that these translocations are secondary, they were not included in the calculation of the frequency of atypical translocations.

Alterations of brain metabolites in metachromatic leukodystrophy as detected by localized proton magnetic resonance spectroscopy in vivo.

The brain morphology and chemistry of seven children with late infantile (4/7) and juvenile (3/7) forms of metachromatic leukodystrophy (MLD) were investigated by magnetic resonance imaging (MRI) and localized proton magnetic resonance spectroscopy (MRS). Patients who were examined at least 6 months after the onset of symptoms (6/7) had severe leukodystrophic changes on MRI. Proton MRS revealed a marked reduction of the neuronal marker N-acetylaspartate in white and grey matter and elevated lactate in demyelinated areas. In contrast to other leukodystrophies MLD patients showed a generalized increase of brain myo-inositol (2- to 3-fold in white matter), indicating a specific role in the pathophysiology of demyelination in MLD.

Immunological and functional determination of the protease inhibitors, protein C and antithrombin III, in liver cirrhosis and in neoplasia.

Using a new rapid coagulant method, protein C activity (PC act) was determined in liver cirrhosis and malignancies and compared with PC antigen and AT III values. PC was decreased in a more pronounced manner than AT III in liver cirrhosis, mainly due to impaired synthesis. This is of special clinical interest because PC proved to be a high sensible indicator of liver cell dysfunction. Decreased levels of PC act (PC ratio act/ag less than 1) in decompensated liver cirrhosis may be caused by the synthesis of dysfunctional PC and/or vitamin K deficiency with production of undercarboxylated PC most sensitively registered by this coagulant assay. An increased clearance of in vivo activated PC induced by DIC may play an insignificant role. In patients with liver metastases, PC act (but not AT III and immunological parameters) was significantly reduced, supporting the conclusion that in these patients liver dysfunction concomitant with synthesis of dysfunctional PC must be discussed as the main cause of this alteration.

Does protamine chloride neutralize low molecular weight heparin sufficiently?

The heparin neutralizing properties of protamine chloride on conventional heparin (porcine mucosa) and on low molecular weight heparin (Kabi 2165) were studied in vitro. Protamine chloride neutralized 99% of the delaying effect of conventional heparin on the activated partial thromboplastin time, whereas only 70% of the effect of low molecular weight heparin was neutralized. The neutralizing effect of protamine chloride on the inhibition of factor Xa (clot test) was 95% for conventional heparin and 55% for low molecular weight heparin, whereas the effect of both heparin preparations on the thrombin inhibition could be completely neutralized. We conclude that conventional heparin is neutralized more effectively in vitro by protamine chloride than is the low molecular weight heparin. The findings do not exclude that protamine chloride is able to suppress in vivo bleedings caused by low molecular weight heparin.