Design of new and sensitive fluorogenic substrates for human kallikrein hK3 (prostate-specific antigen) derived from semenogelin sequences

Human kallikrein hK3 (prostate-specific antigen) is a chymotrypsin-like serine protease which is widely used in the diagnosis of prostate cancer. Assays of the enzymatic activity of hK3 in extracellular fluids have been limited by a lack of sensitive synthetic substrates. This report describes the design of a series of internally quenched fluorescent peptides containing an amino acid sequence based on preferential hK3 cleavage sites in semenogelins. Those were identified by 2-D gel electrophoresis analysis and N-terminal sequencing of semenogelin fragments generated by ex vivo proteolysis in freshly ejaculated semen. These peptides were cleaved by hK3 at the C-terminal of certain tyrosyl or glutaminyl residues with k(cat)/K(m) values of 15000-60000 M(-1) s(-1). The substrate Abz-SSIYSQTEEQ-EDDnp was cleaved at the Tyr-Ser bond with a specificity constant k(cat)/K(m) of 60000 M(-1) s(-1), making it the best substrate for hK3 described to date.

Loss-of-function polymorphism of the human kallikrein gene with reduced urinary kallikrein activity

Kallikrein is synthesized in the distal tubules and produces kinins, which are involved in the regulation of vascular tone in the kidney. Urinary kallikrein activity has been reported to be partly inherited and to be reduced in essential hypertension. In a systematic search for molecular variants of the human kallikrein gene, nine single-nucleotide polymorphisms were identified. Five of those polymorphisms, including two nonsynonymous substitutions in exon 3, i.e., Arg53His (allelic frequency in Caucasian subjects, 0.03) and Gln121Glu (allelic frequency, 0.33), were studied in a normotensive group and two independent hypertensive groups for which 24-h urinary kallikrein activity had been measured. A significant decrease in urinary kallikrein activity was observed for the subjects who were heterozygous for the Arg53His polymorphism, compared with the other subjects. This finding was consistent in the two hypertensive groups and was observed with several kallikrein enzymatic assays. The Gln121Glu polymorphism and the other polymorphisms were not associated with changes in urinary kallikrein activity. None of the polymorphisms was associated with hypertension. Recombinant kallikrein variants were synthesized and enzymatically characterized, using native kininogen and kininogen-derived synthetic peptide substrates. No important effect was observed after Gln121 mutation, but there was a major decrease in enzyme activity when Arg53 was replaced by histidine. A model of kallikrein derived from crystallographic data suggested that Arg53 can affect substrate binding. The identification of a subset of subjects with genetically reduced kallikrein activity as a result of an amino acid mutation could facilitate analysis of the role of the kallikrein-kinin system in renal and vascular diseases.

Amidolytic activity of prostatic acid phosphatase on human semenogelins and semenogelin-derived synthetic substrates

In addition to kallikrein hK3, a serine protease generally reported as PSA (prostate-specific antigen), at least two other enzymes in human seminal plasma also cleave synthetic peptidyl substrates derived from the sequence of human semenogelins. We have identified one of these as prostatic acid phosphatase (PAP), a major component of prostatic fluid whose physiological function is unclear. The other is a high Mr basic protein present at low concentrations in seminal plasma and that remains to be characterized. PAP was purified to homogeneity from freshly ejaculated seminal plasma. Its N-terminal sequence and its phosphatase properties (hydrolysis of para-nitrophenylphosphate at low pH) were determined, and its inhibition by sodium fluoride measured. Both purified and commercial PAP also had amidolytic activity on peptide substrates derived from the semenogelin sequence at neutral and slightly basic pH. The k(cat)/K(m) values were in the 10(2)-10(3) m(-1) x s(-1) range using fluorogenic semenogelin-derived substrates whose peptidyl moiety included cleavage sites that had been identified ex vivo. PAP cleavage sites differed from those of hK3 and were mainly at P1 = Gln residues or between residues bearing hydroxyl groups. PAP amidolytic activity was poorly inhibited by all currently used wide spectrum proteinase inhibitors. Only 3-4 dichloroisocoumarin and benzamidine inhibited purified PAP. Purified human semenogelin was cleaved by purified and commercial PAP at neutral pH; the two main cleavage sites were at Tyr292 and Ser170 (semenogelin I sequence), only the former has been identified ex vivo by analysis of seminal plasma.

[Ischemic cerebrovascular stroke of arterial origin in the child]

Comparing stroke in children with stroke in adults can provide interesting information because age and cerebral plasticity induce specific clinical features and outcome. Arterial ischemic strokes are the most frequent in childhood although the problem is not one of arteriosclerosis. Arterial dissection, Moya-Moya syndrome, and cardioembolic and thrombogenic events induced by hemoglobin diseases and hyperhomocyteinemia must be detected at the first event. In some cases, onset is marked by head trauma or an infectious syndrome. The important feature is that outcome is better than in adults and is marked by onset of hemidystonia, partial epilepsy. Aphasia is benign if stroke arises before the child has learned to write.

A semiparametric approach for the two-sample comparison of survival times with long-term survivors

In the two-sample comparison of survival times with long-term survivors, the overall difference between the two distributions reflects differences occurring in early follow-up for susceptible subjects and in long-term follow-up for nonsusceptible subjects. In this setting, we propose statistics for testing (i) no overall, (ii) no short-term, and (iii) no long-term difference between the two distributions to be compared. The statistics are derived as follows. A semiparametric model is defined that characterizes a short-term effect and a long-term effect. By approximating this model about no difference in early survival, a time-dependent proportional hazards model is obtained. The statistics are obtained from this working model. The asymptotic distributions of the statistics for testing no overall or no short-term effects are ascertained, while that of the statistic for testing no long-term effect is valid only when the short-term effect is small. Simulation studies investigate the power properties of the proposed tests for different configurations. The results show the interesting behavior of the proposed tests for situations where a short-term effect is expected. An example investigating the impact of progesterone receptors status on local tumor relapse for patients with early breast cancer illustrates the use of the proposed tests.

[Daily life activities and multiple sclerosis]

The onset of Multiple Sclerosis usually concerns young adults who are making plans for their life. The personal, familial, professional plans must be adapted to the course of the disease. This adapted daily life must be as normal as possible to prevent the social loneliness which is the principal complication of Multiple Sclerosis. Three frequent situations of daily life have recently been studied in Multiple Sclerosis. Pregnancy is permitted. There is a dramatic decrease of the relapse rate during pregnancy but an obvious increase after delivery. Pregnancy has no influence on disability. Vaccinations do not favor the onset or the worsening of Multiple Sclerosis according to studies with large number of patients (in particular hepatitis B vaccination). Stress is not able to trigger the onset or relapses of Multiple Sclerosis. Stress could even protect against relapses. The Multiple Sclerosis daily life does not need to take specific precautions which would expose to the marginalization of patients.

Interferon-beta treatment in patients with childhood-onset multiple sclerosis

We present a report of the use of interferon-beta before 18 years of age in 16 patients with childhood-onset multiple sclerosis. This study demonstrated that the treatment is safe and well tolerated.

[Multiple sclerosis: spontaneous course, natural history]

Globally, the course and prognosis of multiple sclerosis are heterogeneous, and generally considered to be unpredictable. Advances in statistical techniques have made it possible to analyze representative cohorts of patients to clearly delineate the overall prognosis of the disease, beyond individual variations. For each individual however, there appears to be a steady progression as shown by serial quantified neurological examinations. At the present time early prediction of outcome remains impossible. In the near future, new imaging techniques may provide a solution to this problem allowing selection of patients at risk who could benefit from early treatment.

Insulin-like growth factor binding proteins (IGFBPs) as potential physiological substrates for human kallikreins hK2 and hK3

Insulin-like growth factors (IGFs) are important growth regulators of both normal and malignant prostate cells. Their action is regulated by six insulin-like growth factor binding proteins (IGFBPs). The proteolytic cleavage of IGFBPs by various proteases decreases dramatically their affinity for their ligands and therefore enhances the bioavailability of IGFs. To elucidate the putative biological role of prostatic kallikreins hK2 and hK3 (prostate-specific antigen) in tumour progression, we analyzed the degradation of IGFBP-2, -3, -4 and -5 by these two tissue kallikreins. We found that hK3, already characterized as an IGFBP-3 degrading protease, cleaved IGFBP-4 but not IGFBP-2 and -5, whereas hK2 cleaved all of the IGFBPs much more effectively, and at concentrations far lower than those reported for other IGFBP-degrading proteases. The proteolytic patterns after cleavage of IGFBPs by hK2 and hK3 were similar and were not modified in the presence of IGF-I. Heparin, but not other glycosaminoglycans, enhanced dramatically the ability of hK3 but not hK2 to degrade IGFBP-3 and IGFBP-4. More importantly, the IGFBP fragments generated by hK2 and hK3 had no IGF-binding capacity, as assessed by Western ligand blotting. Our results suggest that the prostatic kallikreins hK2 and hK3 may influence specifically the tumoral growth of prostate cells through the degradation of IGFBPs, to increase IGF bioavailability.

Purification and characterization of active recombinant rat kallikrein rK9

The rat tissue kallikrein rK9 is most abundant in the submandibular gland and the prostate. It has been successfully expressed in the Pichia pastoris yeast expression system. A full-length cDNA coding for the mature rK9 was fused in frame with yeast alpha-factor cDNA. The fusion protein was secreted into the medium with high yield without being processed by the yeast KEX2 signal peptidase. Mature rK9 was efficiently released from the fusion protein by trypsin and was purified to homogeneity by one-step affinity chromatography using soya bean trypsin inhibitor (SBTI) as affinity ligand. The identity of the recombinant enzyme was checked by N-terminal amino acid sequencing, Western blot analysis and kinetic studies. The dual trypsin- and chymotrypsin-like enzymatic specificity of rK9 was assessed by determining specificity constants (k(cat)/K(m)) for the hydrolysis of fluorogenic substrates, the peptide sequences of which were derived from proparathyroid hormone (pro-PTH) and from semenogelin-I. Our results confirmed the presence of an extended binding site in the rK9 active site. We also identified a far more sensitive substrate of this enzyme than those previously described, Abz-VKKRSARQ-EDDnp, which was hydrolysed with a catalytic efficiency k(cat)/K(m) of 420000 M(-1)s(-1). Finally, we showed that four of the five major proteins contained in secretions of rat seminal vesicles were rapidly degraded by recombinant rK9.

A method for shortening instruments using the Rasch model. Validation on a hand functional measure

BACKGROUND

Many measurement instruments, particularly measures of hand functional ability, frequently comprise a large number of items. Reduced versions of these instruments can facilitate their use. This work proposes a new method for shortening an instrument.

METHODS

The method proposed was based on a scale of item difficulty calculated using the Rasch model. It was applied on a hand functional measure comprising 67 tests. The sample included 194 patients with hand lesions. The shortened instrument obtained was compared with those provided by classic methods used in the literature, with item random choice, and with shortened versions proposed by four independent experts, two rehabilitation physicians and two occupational therapists, who are clinicians familiar with the tool. All the statistical analyses were carried out on a random sub-group of two-thirds of the sample. A cross validation was then carried out on the remaining third.

RESULTS

The reduction obtained had score non significantly different from that of the original instrument. In addition, the intra-class correlation coefficient and the Cronbach alpha coefficient were high. Among the different degrees of reduction investigated, the 12-item version seemed to be appropriate. Our method appeared to provide better results in terms of discriminant validity and internal validity than the choices of the four experts. The reductions produced were also better than those obtained by classic methods based on principal component analysis and multiple linear regression, as well as those obtained by random choices of items.

CONCLUSION

The method presented is pertinent and useful. The reduction obtained appeared to be better than the choices of experts and the reductions provided by classic methods. The method could be used in other fields.

Subsite specificity of trypanosomal cathepsin L-like cysteine proteases. Probing the S2 pocket with phenylalanine-derived amino acids

The S2 subsite of mammalian cysteine proteinases of the papain family is essential for specificity. Among natural amino acids, all these enzymes prefer bulky hydrophobic residues such as phenylalanine at P2. This holds true for their trypanosomal counterparts: cruzain from Trypanosoma cruzi and congopain from T. congolense. A detailed analysis of the S2 specificity of parasitic proteases was performed to gain information that might be of interest for the design of more selective pseudopeptidyl inhibitors. Nonproteogenic phenylalanyl analogs (Xaa) have been introduced into position P2 of fluorogenic substrates dansyl-Xaa-Arg-Ala-Pro-Trp, and their kinetic constants (Km, kcat/Km) have been determined with congopain and cruzain, and related host cathepsins B and L. Trypanosomal cysteine proteases are poorly stereoselective towards D/L-Phe, the inversion of chirality modifying the efficiency of the reaction but not the Km. Congopain binds cyclohexylalanine better than aromatic Phe derivatives. Another characteristic feature of congopain compared to cruzain and cathepsins B and L was that it could accomodate a phenylglycyl residue (kcat/Km = 1300 mM-1.s-1), while lengthening of the side chain by a methylene group only slightly impaired the specificity constant towards trypanosomal cysteine proteases. Mono- and di-halogenation or nitration of Phe did not affect Km for cathepsin L-like enzymes, but the presence of constrained Phe derivatives prevented a correct fitting into the S2 subsite. A model of congopain has been built to study the fit of Phe analogs within the S2 pocket. Phe analogs adopted a positioning within the S2 pocket similar to that of the Tyr of the cruzain/Z-Tyr-Ala-fluoromethylketone complex. However, cyclohexylalanine has an energetically favorable chair-like conformation and can penetrate deeper into the subsite. Fitting of modeled Phe analogs were in good agreement with kinetic parameters. Furthermore, a linear relationship could be established with logP, supporting the suggestion that fitting into the S2 pocket of trypanosomal cysteine proteases depends on the hydrophobicity of Phe analogs.

Relapses and progression of disability in multiple sclerosis

BACKGROUND

The influence of the patterns of onset of multiple sclerosis and relapses of the disease on the time course of irreversible disability is controversial.

METHODS

In 1844 patients with multiple sclerosis who were followed for a mean (+/- SD) of 11 +/- 10 years, we determined the time of the clinical onset of the disease, the initial course (relapsing-remitting or progressive) and the subsequent course (relapsing-remitting, secondary progressive, or primary progressive), the times of relapses, the time to the onset of irreversible disability, and the time course of progressive, irreversible disability. We used three scores on the Kurtzke Disability Status Scale (range, 0 to 10, with higher scores indicating more severe disability) as measures of the severity and progression of disability: a score of 4 (limited walking ability but able to walk for more than 500 m without aid or rest), a score of 6 (ability to walk with unilateral support no more than 100 m without rest), and a score of 7 (ability to walk no more than 10 m without rest while leaning against a wall or holding onto furniture for support). We used Kaplan-Meier analyses to determine the influence of relapses on the time to the onset of irreversible disability.

RESULTS

The median times from the onset of multiple sclerosis to the assignment of a score of 4, a score of 6, and a score of 7 on the disability scale were longer among the 1562 patients with a relapsing-remitting onset of disease (11.4, 23.1, and 33.1 years, respectively) than among the 282 patients who had progressive disease from the onset (0.0, 7.1, and 13.4 years, respectively; P<0.001 for all comparisons). In contrast, the times from the assignment of a score of 4 to a score of 6 were similar in the two groups (5.7 and 5.4 years, P=0.74). The time course of progressive, irreversible disease among patients with the primary progressive type of multiple sclerosis was not affected by the presence or absence of superimposed relapses.

CONCLUSIONS

Among patients with multiple sclerosis, relapses do not significantly influence the progression of irreversible disability.

Does selenium reduce the risk of threatened preterm delivery associated with placental cytochrome P450-1A1 activity?

Selenium (Se), an essential trace element in human nutrition, is thought to have an important role in the prevention of oxygen damage by organic hydroperoxides generated by oxidative metabolism. Epidemiological studies have shown an association between placental cytochrome P450-1A1 (CYP1) activity and threatened preterm delivery (TPD), and other experimental studies have shown alterations in fetal development with CYP1 activity or toxicity. The present study examined the possible protective effect of selenium on the potential toxicity of maternal exposure to polycyclic aromatic hydrocarbons (PAHs) on the normal course of pregnancy. Placental CYP1 activity was used as a risk factor resulting from maternal exposure to PAHs. TPD occurrence was used as a general indicator of troubles in the normal course of pregnancy. A group of TPD patients and a group of controls were selected from 178 pregnant women attending obstetrical care in a maternity hospital. Selenium concentrations in maternal plasma were lower in the TPD group: 63.7 ng/ml (CI 95% confidence bounds = 43.6-82.2) vs 69.2 ng/ml (CI 95% confidence bounds = 49. 3-96.3) (t test, P<0.01). When placental CYP1 was induced, an association between TPD and selenium was found, with an increase of 10 ng/ml for the latter. An adjusted odds ratio of 0.55 (CI 95% confidence bounds = 0.34-0.88; chi(2), P<0.01) was estimated. When placental CYP1 was not activated, the odds ratio was estimated at 0.99 (CI 95% confidence bounds=0.95-1.03; NS). This epidemiologic finding suggests that antioxidant Se status may be a protective factor against the potential toxic effect of PAHs on the normal course of pregnancy. The downward trend that we observed supports the hypothesis that the one-electron pathway metabolism of PAHs may explain a large fraction of TPD and some preterm deliveries.

Migraine history and migraine-induced stroke in the Dijon stroke registry

Two thousand three hundred and eighty-nine patients with first-ever stroke were registered in the population-based Dijon Stroke Registry over an 11-year period. There was a history of migraine in 49 cases (2%), with a majority of women (2.8% versus 1.1% men) with the following distribution: 27 cases among 1,380 large-artery cerebral infarctions (1.9%), 6 cases among 358 small-artery cerebral infarctions (1.6%), 6 cases among 412 cerebral infarctions due to cardiac embolism (1.4%), 7 cases among 191 cerebral hemorrhages (3. 6%) and 3 cases among 47 subarachnoid hemorrhages (6.3%). The male/female ratio was 0.58 for the 49 strokes with a history of migraine versus 1.27 for the 2,340 strokes with no history of migraine. Twelve migraine-induced ischemic strokes occurred with an infarction of the posterior area of the brain in young patients. The annual incidence was 0.80/100,000/year (confidence interval, CI = 0. 37-1.57) with a predominance of women (1.02/100,000/year, CI = 0. 52-1.25; men: 0.57/100,000/year; CI = 0.28-1.04). We conclude that a history of migraine is more frequent in women, in particular in those with hemorrhagic strokes, and that the incidence of migraine-induced stroke in our population-based study is higher in women, although it remains low.

[Can the prognosis of multiple sclerosis be predicted?]

Though the global course of the disease is well known when considering large cohorts of patients, it is rather difficult to make a prognosis for a given patient. It is essential however to predict the course of the disease as early as possible in order to be able to give the patient the right treatment at the right time. Age at disease onset is one of the most important clinical predictive factors, as this has been proved by various analyses. The earlier the disease onset, the better the prognosis. The inaugural symptom of optic neuritis, the long interval between the first two relapses, a remitting form at onset are predictive factors of a good evolution. A normal brain magnetic resonance imaging performed on the occasion of a first isolated sign of the central nervous system is the marker of a good prognosis. Conversely, the presence of oligoclonal bands in the cerebrospinal fluid and the increase of IgG index increase the risk of occurrence of a second relapse. The new techniques of magnetic resonance imaging and the exhaustive initial clinical examination using several classifications of disability will allow a better prognosis for a given patient.

Incidence of multiple sclerosis in Dijon, France: a population-based ascertainment

Incidence of multiple sclerosis (MS) was prospectively determined within the population of the city of Dijon (94,000 inhabitants under 60 years old) at 47 degrees northern latitude, in Burgundy, France. All the incident cases were diagnosed according to the criteria of Poser, associated to the study of cerebrospinal fluid, evoked potentials and cerebral magnetic resonance imaging. Diagnosis was assessed in all the cases by a neurologist working either in the University Hospital (four neurologists) or in private offices (seven neurologists). The ascertainment was performed on a full 5-year period, from 1993 to 1997. Twenty-one cases were diagnosed in the population of 94,000 inhabitants, with an incidence of 6.1/100,000/year in women, 3.3/100,000/year in men and 4.3/100,000/year in both sexes. The sex-ratio female/male was 2.5. Our data are similar to those of the literature, in particular in countries around the Burgundy area. Our data allow evaluation of the burden of MS in our area and allow evaluation of the changes of incidence in the future.

Variation over time of the effects of prognostic factors in a population-based study of colon cancer: comparison of statistical models

The authors compare the performance of different regression models for censored survival data in modeling the impact of prognostic factors on all-cause mortality in colon cancer. The data were for 1,951 patients, who were diagnosed in 1977-1991, recorded by the Registry of Digestive Tumors of Côte d'Or, France, and followed for up to 15 years. Models include the Cox proportional hazards model and its three generalizations that allow for hazard ratio to change over time: 1) the piecewise model where hazard ratio is a step function; 2) the model with interaction between a predictor and a parametric function of time; and 3) the non-parametric regression spline model. Results illustrate the importance of accounting for non-proportionality of hazards, and some advantages of flexible non-parametric modeling of time-dependent effects. The authors provide empirical evidence for the dependence of the results of piecewise and parametric models on arbitrary a priori choices, regarding the number of time intervals and specific parametric function, which may lead to biased estimates and low statistical power. The authors demonstrate that a single, a priori selected spline model recovers a variety of patterns of changes in hazard ratio and fits better than other models, especially when the changes are non-monotonic, as in the case of cancer stages.

Short and long-term effects on survival in breast cancer patients treated by primary chemotherapy: an updated analysis of a randomized trial

A potential advantage of primary over adjuvant chemotherapy in breast cancer survival had been proposed on theoretical grounds. In 1994, early results of the S6-trial comparing primary chemotherapy vs. adjuvant chemotherapy for operable breast cancer in 390 premenopausal patients had shown significant improvement in survival of the primary chemotherapy arm (p = 0.04). An updated analysis conducted in 1995 showed the disappearance of this difference between the two arms (p = 0.18). In the present analysis, we investigated the potential short and long-term benefits attributable to primary chemotherapy by applying weighted logrank tests designed to assess specifically these effects. Results were compared to those obtained with the classical logrank test. At a median follow-up of 105 months, a significant short-term survival benefit (p = 0.02) in favor of the primary chemotherapy has been shown. However, no long-term survival benefit (p = 0.36) could be documented. The classical logrank test had revealed no significant difference (p = 0.24) between the two groups but the proportional hazard assumption being rejected (p = 0.04), the efficiency of this test can be questioned. Results using the present analysis suggested that primary chemotherapy delayed early death rates, without significantly modifying long-term event rates. It emphasizes that a short-term effect which is not necessarily associated with a long-term benefit may be seen at an early evaluation and disappear later on.

[Dental amalgam and multiple sclerosis: what is the connection?]

BACKGROUND

There is some debate concerning a possible relationship between dental fillings and multiple sclerosis. Many patients ask their dentist to remove fillings.

TOXICITY

Dental fillings contain mercury (more than 50%) which can cross the blood-brain barrier. Massive mercurial intoxication is neurotoxic both for the central and peripheral nervous system. Dental fillings release as much mercury in 24 hours as is ingested in a normal meal, i.e. a level well under the neurotoxicity level.

RELATIONSHIP

Mercurial poisoning is histologically, clinically, immunologically, and toxicollogically different from multiple sclerosis. Based on data available today, it is not warranted to propose removing dental fillings.

Unobserved covariates in the two-sample comparison of survival times: a maximum efficiency robust test

In analysing a clinical trial with the logrank test, the hazards between the two groups are usually assumed to be proportional. Nevertheless, this hypothesis is no longer valid with unobserved covariates. As a consequence, there is a loss of power of the logrank test for testing the null hypothesis H(0) of no treatment effect. We propose a test suited for taking into account unobserved covariates. The proposed approach is based on a proportional hazard frailty model whereby the omitted covariates are considered as an unobserved frailty variable. The procedure is as follows. In a first step, the weighted logrank test optimal for testing H(0) against a general proportional hazard frailty model is obtained and its specialization for a gamma frailty variable is derived. In a second step, the proposed test is obtained by combining the maximin efficiency robustness principle and the gamma frailty distribution properties. Simulation studies investigate the power properties of the test for different frailty distributions. A breast cancer clinical trial is analysed as an example. The proposed test might be recommended rather than the logrank for practical situations in which one expects heterogeneity related to omitted covariates.

New, sensitive fluorogenic substrates for human cathepsin G based on the sequence of serpin-reactive site loops

Cathepsin G has both trypsin- and chymotrypsin-like activity, but studies on its enzymatic properties have been limited by a lack of sensitive synthetic substrates. Cathepsin G activity is physiologically controlled by the fast acting serpin inhibitors alpha1-antichymotrypsin and alpha1-proteinase inhibitor, in which the reactive site loops are cleaved during interaction with their target enzymes. We therefore synthesized a series of intramolecularly quenched fluorogenic peptides based on the sequence of various serpin loops. Those peptides were assayed as substrates for cathepsin G and other chymotrypsin-like enzymes including chymotrypsin and chymase. Peptide substrates derived from the alpha1-antichymotrypsin loop were the most sensitive for cathepsin G with kcat/Km values of 5-20 mM-1 s-1. Substitutions were introduced at positions P1 and P2 in alpha1-antichymotrypsin-derived substrates to tentatively improve their sensitivity. Replacement of Leu-Leu in ortho-aminobenzoyl (Abz)-Thr-Leu-Leu-Ser-Ala-Leu-Gln-N-(2, 4-dinitrophenyl)ethylenediamine (EDDnp) by Pro-Phe in Abz-Thr-Pro-Phe-Ser-Ala-Leu-Gln-EDDnp produced the most sensitive substrate of cathepsin G ever reported. It was cleaved with a specificity constant kcat/Km of 150 mM-1 s-1. Analysis by molecular modeling of a peptide substrate bound into the cathepsin G active site revealed that, in addition to the protease S1 subsite, subsites S1' and S2' significantly contribute to the definition of the substrate specificity of cathepsin G.

Modeling of high-cost patient distribution within renal failure diagnosis related group

Modeling by mixed-distribution was proposed in order to analyze heterogeneity of costs and length of stays within Diagnosis Related Groups (DRGs). A mixed-distribution model based on Weibull distributions was applied to 791 discharge abstracts of French DRG no. 450 (Health Care Financing Administration 3 DRG no. 316 "Renal failure") from a national database. Three subgroups of cost and length of stay were identified. Except for age, clinical criteria significantly linked with the long-stay subgroup were the same as those associated with the high-cost subgroup: acute renal failure, intensive care, infectious complications, and vascular investigations. The identification of factors associated with high costs, based on the proposed model, will allow physicians to understand more accurately how their choice of specific procedures influences hospital costs.

[Multiple sclerosis and pregnancy: clinical issues]

Multiple sclerosis (MS) is the most common chronic disabling neurological disease affecting young women. Paradoxically, our knowledge of the relationship between pregnancy and MS is limited. However, several conclusions emerge from the literature: 1) The rate of relapse in MS decreases during pregnancy, and it rises significantly during the first three months post partum before coming back to its level prior to pregnancy. 2) Although pregnancy and delivery cause changes of the relapse rate, they have no influence on mid and long term residual disability. 3) Breast-feeding and epidural analgesia do not seem to have any deleterious effect on the disease. 4) Lastly, MS does not seem to influence pregnancy, delivery or the child's health. The studies available to date suffer from methodological limitations. They need to be confirmed by prospective studies. This is the purpose of the study entitled "Pregnancy in multiple sclerosis, PRIMS", which has been carried out since 1992 at the European level.

Incidence trends of ischemic stroke and transient ischemic attacks in a well-defined French population from 1985 through 1994

BACKGROUND AND PURPOSE

The changing incidence of ischemic stroke is of major concern in view of its public health impact, to define the population concerned, to identify risk factors, and to set up health-care systems. The aim of this study was to evaluate the time trends associated with the incidence of all the subtypes of ischemic stroke and transient ischemic attacks in a well-defined population for 10 years.

METHODS

Since 1985, a population registry has recorded each patient living in Dijon (France) who suffered from a cerebrovascular disease (CVD) regardless of the type of management. This study involved all patients suffering from their first ischemic stroke and their first transient ischemic attacks (TIAs) during 1 calendar year between January 1, 1985 and December 31, 1994. The incidence changes according to age, sex, and type of cerebral ischemic event (cortico-subcortical infarct, lacunar infarct, and TIA) were studied on the basis of their annual variations.

RESULTS

During the 10-year study period, 834 cortico-subcortical infarcts (52.1%), 296 lacunar infarcts (18.5%), 369 TIAs (23.1%), and 101 undetermined ischemic strokes (6.3%) were collected. The incidence of all ischemic events was relatively stable in both sexes over the 10-year period. However, the incidence rates differed according to age and type of ischemia. An increased incidence of cerebral cortico-subcortical infarct was observed in patients older than 75 years of age (+5.45% annual change [AC] in men, P<0.05; +5. 09% AC in women, NS). In parallel, a higher proportion of emboligenic cardiac arrhythmias was observed in these patients (P<0. 001). The incidence of lacunar infarcts tended to decrease, regardless of age but mainly in men under younger than 75 years of age (-12.74% AC in men, NS; +0.31% AC in women, NS). The incidence of TIAs was relatively stable in both sexes. Because our population consisted of a large number of elderly subjects, the increase in cardioembolic causes could partially explain the increased incidence of cerebral cortico-subcortical infarcts in patients older than 75 years of age.

CONCLUSIONS

These preliminary data emphasize the importance of stroke surveillance in considering the variations of the different mechanisms of ischemic cerebrovascular disease. Although the incidence of TIA is stable and the incidence of lacunes tends to decrease in men, mainly before 75 years of age, we emphasize the rise of the crude incidence of cortico-subcortical infarcts in men older than 75 years of age, induced by an increase in cardioembolic causes.

Aryl hydrocarbon hydroxylase activity in human placenta and threatened preterm delivery

Induction of aryl hydrocarbon hydroxylase (AHH) activity in the placenta has been well documented. This enzyme may be induced by a variety of Polycyclic Aromatic Hydrocarbons (PAHs) and the AHH inducibility is associated with harmful effects of environmental chemicals. Toxic effects of PAHs in tissues such as placenta have been demonstrated to be due to their metabolites, epoxides, which interact with DNA. Thus, environmental PAHs may be related to its alterations in fetal development. Founded on these findings the PAH metabolites could interfere with the normal course of the pregnancy and may be an aborticide, a teratogen or a carcinogen. We hypothesize that low increased activity of placental Aryl Hydrocarbon Hydroxylase (AHH) may be an important determinant of human fetotoxicity. The present investigation was designed to examine the possible implications of PAH exposure at environmental exposure levels on the normal course of the pregnancy using AHH induction as an indicator of PAH exposure. Threatened Preterm Delivery (TPD) was used as an index of problems in the normal course of pregnancy. A group of forty pregnancies at term with TPD was compared with eighty controls for placental AHH induction. Macroscopic placental examination was also performed. A significant increase in prevalence of placental AHH induction with TPD was shown (Odds-Ratio = 2.8; 95% confidence bounds [1.3-6.2]; chi 2 = 6.7 p < 0.01). No such increases were found associated with placental pathology. When taking into account the group of placenta without basal plate calcifications, the significant increase in prevalence of placental AHH induction with TPD above mentioned was greatly increased (Odds-Ratio = 8.9; 95% confidence bounds [2.4-32.9]; chi 2 = 11.1 p < 0.001) controlling for gestational age. The increase in prevalence of placental AHH induction with TPD disappeared when taking into account the subgroup with basal plate or parenchyma calcifications. It is hypothesized that the high estrogen and progesterone at term may explain these associations.

Headache in hypothyroidism. Prevalence and outcome under thyroid hormone therapy

OBJECTIVE

To evaluate the frequency of headache in patients with hypothyroidism.

DESIGN

A prospective study of a cohort of patients with hypothyroidism.

SETTING

Outpatients or inpatients in a headache clinic and endocrinological clinic.

PATIENTS

102 adults, ages 35 to 78 (83F, 19M) experiencing clinical and biological hypothyroidism.

RESULTS

Thirty-one patients with hypothyroidism of 102 (30%) presented with headache 1 to 2 months after the first symptoms of hypothyroidism. The headache was slight, nonpulsatile, continuous, bilateral, and salicylate responsive and disappeared with thyroid hormone therapy.

CONCLUSION

The authors believe there is a prevalence of nonspecific headache in hypothyroidism and that it has a particular response to thyroid hormone therapy. Hypothyroidism is another cephalalgia with an endocrinological cause after menstrual cephalalgia. We suspect a metabolic or vascular pathophysiological process.

Course of valvular strands in patients with stroke: cooperative study with transesophageal echocardiography

BACKGROUND

Native valve strands might be related to the acute stage of thrombosis or might suggest a long-term valvular change. We aimed to estimate changes in the strands in patients with stroke through a serial transesophageal echocardiographic (TEE) study.

METHODS AND RESULTS

A study was conducted among patients who were referred for TEE for stroke or cardiac pathology. Patients had TEE examinations with a 5-MHz multiplane TEE probe. Echocardiography was repeated 3 months later in patients with stroke. TEE was performed in 180 patients admitted to cardiology units and in 160 patients referred to neurology units. Among 34 patients with valvular strands, 30 were referred to neurology for stroke, whereas 4 patients were admitted to cardiology (18.8% versus 2.2%, difference 16.5%, 95% confidence interval 10% to 22.9%, P =.001). Strands were located on the mitral valve in 16 patients, the aortic valve in 6 patients, and both left heart valves in 8 patients. Among the 38 valves with strands, 17 (44. 7%) were morphologically normal, 4 (10.5%) were thickened, 7 (18.4%) were redundant, and 10 (26.3%) had both abnormalities. TEE showed other abnormalities in 16 (53.3%) patients, whereas 14 patients had only strands. Twenty-six (86.6%) patients had a second TEE study 3 months later. Strands were not found in 4 (15.4%) patients (95% confidence interval 4.3% to 34.9%).

CONCLUSIONS

Valvular thickening or redundancy may predispose valves to strand formation. Native valve strands usually persist and thus reflect a chronic valvular change.

[A brachial form of motor neuropathy caused by lead poisoning]

We report the case of a 48-year-old patient who developed acute onset bilateral, peripheral motor dysfunction in the arms and forearms. Clinical history, electromyography and laboratory tests confirmed the diagnosis of peripheral neuropathy caused by lead poisoning from the domestic water supply. The EMG showed axonal alterations. Improvement was observed after treatments with chelating agents and removal of the source of poisoning. This case provides the opportunity to recall the traditional 1889 Dejerine classification of lead-related peripheral neuropathies and is a warning signal that lead poisoning remains a problem in peri-urban areas of developed countries.

[Is it possible to predict the evolution of multiple sclerosis?]

Three characteristic features describe our understanding of the clinical course and outcome in multiple sclerosis: a validated statistical model of disease progression, wide interindividual variability, and a fixed rate of progression in an individual patient. However for and individual patient, it is still impossible to derive a precise and exact prediction of disease outcome, the only reliable method is the deterministic approach developed by Fog and Linneman in 1970 which consists in objective quantitative neurological examinations performed at three month intervals over several years in the same patient. In routine practice, this method in rather unrealistic. Bran MRI data with conventional techniques are also poorly discriminant. Conversely, it may be anticipated that new magnetic resonance techniques, more sensitive to axonal loss, demyelinization and gliosis, will provide reliable answers to this issue upon which therapeutic decisions depend.

Epilepsy in patients with multiple sclerosis: radiological-clinical correlations

PURPOSE

To determine potential mechanisms of epilepsy in patients with multiple sclerosis (MS).

METHODS

Among 402 patients with clinically and radiologically defined MS, including de novo cases, presenting to the Neurology Service, University Hospital of Dijon, we identified 17 with epileptic seizures (4.25%). Among them, the percentage with partial seizures (50%) was greater than that in the reference population.

RESULTS

In most of the patients with MS, plaques were localized in the frontal region, associated with frontal and callosal atrophy, a frontal syndrome, and severe disability status (as assessed by a standard scale). Magnetic resonance imaging (MRI) showed numerous subcortical plaques. Seizures generally were well controlled with antiepileptic drugs (AEDs).

CONCLUSIONS

Our data suggest that the subcortical plaques of MS underlie seizure activity in patients with MS and epilepsy.

Rate of pregnancy-related relapse in multiple sclerosis. Pregnancy in Multiple Sclerosis Group

BACKGROUND AND METHODS

Multiple sclerosis often occurs in young women, and the effect of pregnancy on the disease is poorly understood. We studied 254 women with multiple sclerosis during 269 pregnancies in 12 European countries. The women were followed during their pregnancies and for up to 12 months after delivery to determine the rate of relapse per trimester and the score on the Kurtzke Expanded Disability Status Scale (range, 0 to 10, with higher scores indicating more severe disability). The relapse rate in each trimester was compared with the rate during the year before the pregnancy. The effects of epidural analgesia and breast-feeding on the frequency of relapse during the first three months post partum and the disability score at 12 months post partum were also determined.

RESULTS

The mean (+/-SD) rate of relapse was 0.7+/-0.9 per woman per year in the year before pregnancy; it was 0.5+/-1.3 during the first trimester (P=0.03 for the comparison with the rate before pregnancy), 0.6+/-1.6 during the second trimester (P=0.17), and 0.2+/-1.0 during the third (P<0.001). The rate increased to 1.2+/-2.0 during the first three months post partum (P<0.001) and then returned to the prepregnancy rate. The mean Kurtzke disability score worsened by 0.7 point during 33 months of follow-up, with no apparent acceleration during the post-partum period. Neither breast-feeding nor epidural analgesia had an adverse effect on the rate of relapse or on the progression of disability in multiple sclerosis.

CONCLUSIONS

In women with multiple sclerosis, the rate of relapse declines during pregnancy, especially in the third trimester, and increases during the first three months post partum before returning to the prepregnancy rate.

The interest of surgical closure of patent foramen ovale after stroke: a preliminary open study of 8 cases

The risk of stroke and the risk of recurrent strokes in patients with patent foramen ovale (PFO) need a prevention that still remains a therapeutic problem. There are 4 preventive treatments: anti-agregants, anti-coagulants, transcatheter closure, and surgical closure of PFO. The aim of this study was to demonstrate that surgical closure of PFO is safe and useful for prevention of strokes. Eight patients with stroke and PFO diagnosed by transesophageal echography (TEE) were prospectively selected for surgical closure. It was necessary to be younger than 70 years, not to have another cause of stroke, and to have either recurrent strokes or several ischemic lesions on MRI, isolated for PFO associated with an atrial septal aneurysm, and to have a Valsalva maneuver or cough inducing the stroke. For these reasons, these patients were considered to be an homogenous group with a strong relationship between the PFO and the stroke, and with a high risk of recurrence of stroke. The 8 patients had a direct suture of the PFO with a cardiopulmonary bypass. All patients were followed-up with clinical, MRI and TEE examinations during 12 months after surgery. No surgical complications were observed. After one year, without any anticoagulant treatment, no recurrent stroke or transient ischemic attack, no new ischemic lesions on MRI, nor neuropsychological disturbance were noted. No post-surgical inter-atrial right-to-left shunting was observed. In the absence of controlled studies to guide therapeutic options, our data suggest that surgical closure of PFO in patients with stroke, is safe and efficacious to prevent recurrent stroke without any anticoagulants in the first year of follow-up. Further studies are needed to evaluate the long-term role of surgical closure of PFO as an alternative to prolonged anti-thrombotic treatment.

Purification and characterization of a new cystatin inhibitor from Taiwan cobra (Naja naja atra) venom

Cobra cystatin, a new cysteine-proteinase inhibitor of the cystatin superfamily, was isolated from the venom of the Taiwan cobra (Naja naja atra) by affinity chromatography on S-carboxymethylpapain-Sepharose and reverse-phase chromatography. The venom contained two forms of the inhibitor, one of 11870 Da and the other of 12095 Da, as determined by MS, and pI values of 6.2 and 6.1. Cobra cystatin strongly inhibits cysteine proteinases of the papain family, but not calpain. Papain, cathepsin L, cathepsin B and cathepsin S are inhibited with Ki values of 0.19, 0.1, 2.5 and 1.2 nM respectively. The amino acid sequence of cobra cystatin shows that it is a Type 2 cystatin. The amino acid sequence is 73% identical with that of the cystatin in African-puff-adder (Bitis arietans) venom, with which it shares a unique six-residue insertion in a region opposite the reactive inhibitory site. Cobra cystatin is 25-42% identical with other Type 2 cystatins, the most closely related being the recently described human cystatin M, which also has a similar five-residue insertion starting at position 76 (chicken cystatin numbering). A molecular phylogenetic tree of 16 representative members of Family 2 cystatins was constructed by parsimony analysis; it suggests that snake cystatins, together with Tachypleus tridentatus (Japanese horseshoe crab) cystatin and human cystatin M, form a new subfamily within cystatin Family 2.

Kininogen-derived fluorogenic substrates for investigating the vasoactive properties of rat tissue kallikreins--identification of a T-kinin-releasing rat kallikrein

Peptide substrates with intramolecularly quenched fluorescence that reproduce the rat kininogen sequences at both ends of the bradykinin moiety were synthesized and used to investigate the kinin-releasing properties of five rat tissue kallikreins (rK1, rK2, rK7, rK9, rK10). Substrates derived from rat H- and L-kininogen were cleaved best by rK1, especially that including the N-terminal insertion site of bradykinin, Abz-TSVIRRPQ-EDDnp(Abz = O-aminobenzoyl, EDDnp = ethylenediamine 2,4-dinitrophenyl), which was cleaved at the R-R bond with a k(cat)/Km of 12400 mM(-1) s(-1). Replacement of the P2' residue Pro by Val in Abz-TSVIRRPQ-EDDnp gave a far less specific substrate that was rapidly hydrolysed by all five rat kallikreins and human kallikrein hK1. Peptidyl-N-methyl coumarylamide substrates, which lack prime residues, also had low specificities. The importance of the P2' residue for rK1 specificity was further demonstrated using a human-kininogen-derived substrate that included the N-terminal insertion site of bradykinin (Abz-LMKRP-EDDnp). This was cleaved at the M-K bond by hK1 (kallidin-releasing site), but at the K-R bond (bradykinin-releasing site) by rK1. Competition experiments with Abz-TSVIRRPQ-EDDnp, which is resistant to most kallikreins, and Abz-TSVIRRVQ-EDDnp, a general kallikrein substrate, demonstrated that the former competitively inhibited hydrolysis by rK9 and hK1, with Ki values similar to the Km values for the substrate. Thus Pro in P2' does not prevent the peptide binding to the enzyme active site, but impairs cleavage of the scissile bond. The T-kininogen-derived substrate with the T-kinin C-terminal sequence (Abz-FRLVR-EDDnp) was cleaved by rK10 (k(cat)/Km = 2310 mM(-1) s(-1)) and less rapidly by rK1, rK7 and hK1, at the R-L bond, while that corresponding to the N-terminal (Abz-ALDMMISRP-EDDnp) of T-kinin was resistant to all five kallikreins used, suggesting that none has T-kininogenase activity. But this substrate was hydrolysed by a semipurified sample of submandibular gland extract. Another kallikrein, identified as kallikrein rK3, was isolated from this fraction and shown to hydrolyze Abz-ALDMMISRP-EDDnp; rK3 also specifically released T-kinin from purified T1/T2-kininogen after HPLC fractionation. Injection of purified rK3 and of Abz-ALDMMISRP-EDDnp-cleaving fractions into the circulation of anesthesized rats caused transient falls in blood pressure, as did purified rK1 but none of the other purified rat or human kallikreins. This effect occurred via activation of the kinin system since it was blocked by Hoe140, a kinin receptor antagonist.

[Modelling of length of stay and costs in 2 homogeneous groups of hematological and pneumological patients: clinical characterization of patients with long-stay and high costs]

After the implementation of the Medicare Prospective Payment System (PPS) in the USA, many European countries like France have introduced DRGs to curb hospital overspending. However, there has been some reluctance from hospital actors, especially because of the heterogeneous nature of DRG's. To analyse this situation, we propose a method based on distribution modelization of length of stays and costs within DRGs. For each DRG, the model is based on a mixture of Poisson and Weibull distributions identified as subgroups. The subgroups are characterized by their means and their proportions which are estimated by maximization of data likelihood. For a particular DRG, the proportion of long stay or high-cost patients can be explained by the introduction of clinical variables in the model. First the model was applied to the DRG "leukemia and lymphoma" (HCFA V.3), using 133 discharge abstract files from the Dijon public teaching hospital which were classified into this DRG in 1993. Among the studies parameters only acute leukemia, neutropenia < 500 PNN/mm3, high dose aplastic chemotherapy, central venous catheterization, parenteral nutrition, use of protected or laminar air flow room, septicemia, large spectrum intravenous antibiotherapy, and blood transfusion had a significant influence on the distribution of the patients in the long stay or costly subgroup. Second, for DRG "chronic bronchopneumopathies" (n = 220) the significant parameters were mechanical ventilation, antibiotherapy, post hospitalization medicalized care.

[Nicotine and worsening myasthenia]

We report a case of myasthenia gravis worsened by a nicotine transdermal system, in a man who usually was smoking fourty cigarettes per day without any worsening of his symptomatology. He noted an increased bilateral ptosis, total ophtalmoplegia, difficulty in chewing and generalized weakness two hours after application of a nicotine transdermal system, the symptoms improving after he removed it. Cholinergic receptors involved in myasthenia gravis are nicotinergic, and their number at the neuromuscular junction is reduced in myasthenia gravis. That leads to a "functional overdosage" after application of the nicotine transdermal system similar to the cholinergic crisis. This case can be compared with myasthenia syndromes described during the Second World War in tobacco chewers without any muscle impairment.

Mechanism of first-dose cytokine-release syndrome by CAMPATH 1-H: involvement of CD16 (FcgammaRIII) and CD11a/CD18 (LFA-1) on NK cells

The administration of the immunosuppressive humanized monoclonal antibody CAMPATH 1-H, which recognizes CD52 on lymphocytes and monocytes, is associated with a first-dose cytokine-release syndrome involving TNFalpha, IFNgamma, and IL-6 clinically. In vitro models have been used to establish the cellular source and mechanism responsible for cytokine release, demonstrating that cytokine release is isotype dependent, with the rat IgG2b and human IgG1 isotype inducing the highest levels of cytokine release, which was inhibited with antibody to CD16, the low affinity Fc-receptor for IgG (FcgammaR). Cross-linking antibody opsonized CD4 T lymphocytes failed to stimulate TNFalpha release, which together with the observation that TNFalpha release by purified natural killer (NK) cells stimulated by fixed autologous CAMPATH 1-H-opsonized targets was inhibited with anti-CD16, indicates that cytokine release results from ligation of CD16 on the NK cells, rather than Fc-receptor (FcR)-dependent cross-linking of CD52 on the targeted cell. Since the hierarchy of isotypes inducing cytokine release in these cultures matches that seen clinically, we conclude that ligation of CD16 on NK cells is also responsible for cytokine release after injection of CAMPATH 1-H in vivo.

Homology modelling of rat kallikrein rK9, a member of the tissue kallikrein family: implications for substrate specificity and inhibitor binding

The rat kallikrein rK9 is one of the six members of the rat tissue kallikrein family isolated to date. It is 84% identical to rK2 (tonin), and both proteinases are thought to have vasoconstrictive properties. Recently we have shown that rK9 and rK2 have distinct substrate specificities and sensitivities to inhibitors, despite their similar sequences. Unlike all other mammalian kallikrein-related proteinases, rK9 is resistant to inhibition by aprotinin. We have developed a 3-D model of rK9, based on the known X-ray structures of rK2, porcine kallikrein and bovine trypsin, to identify the structural features underlying this functional diversity. The final rK9 model is structurally similar to rK2, but variable regions surrounding the active site differ quite markedly from the reference proteins. The kallikrein loop, which differs from that in porcine kallikrein by a seven-residue insertion, has been generated de novo and subjected to simulated annealing to assess its influence on the restricted substrate specificity of these proteinases. The proposed conformation of the specificity pocket in rK9 differs from that of other serine proteinases, but it can still accommodate both aromatic and basic amino acid side chains at the substrate P1 position, thus explaining the dual chymotrypsin and trypsin-like activity of rK9. The electrostatic potentials of rK9 and aprotinin were calculated using the finite difference Poisson-Boltzmann method. They indicated a large positive region near the active site of rK9 not found in related proteinases because of positively charged residues at positions 61 and 65 in rK9. They generate a positive region, which overlaps a positive region in aprotinin, and may prevent aprotinin binding. A single mutation in aprotinin is suggested that might allow kallikrein rK9 inhibition by aprotinin. This model contributes significantly to our understanding of the structure-function relationships among proteinases of the tissue kallikrein family.

[Familial epilepsy seizure disclosing long QT syndrome]

The Romano-Ward syndrome shows a congenital prolonged QT on the electrocardiogram. It is often revealed by syncopes, sudden death and, in rare cases, by an epileptic attack. We report the cases of two sisters presenting this syndrome. One of them presented an inaugural epileptic attack. The electrocardiogram returned to normal and the seizures disappeared after a treatment with beta-bloquants.