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Biomedical subjects

C Camus

Publications and source records attributed to C Camus.

At least 19 recordsLinked to original sources
PubMed2006

Comparison of epidemiological, clinical, and biological features of invasive aspergillosis in neutropenic and nonneutropenic patients: a 6-year survey.

BACKGROUND: Invasive aspergillosis is an opportunistic infection that occurs mainly among patients with prolonged neutropenia. Few data are available on invasive aspergillosis in nonneutropenic patients. METHODS: The aim of this survey was to compare neutropenic and nonneutropenic patients who had received a diagnosis of invasive aspergillosis at our institution during a 6-year period. RESULTS: Among the 88 cases of invasive aspergillosis analyzed here, 12 were histologically proven, 52 were probable, and 24 were possible. Forty-seven percent of cases were diagnosed in the intensive care unit, and 40% were diagnosed in hematology units. Neutropenia was a risk factor for 52 patients (59%), most of whom had hematological or solid malignancies. Among the 36 nonneutropenic patients (41%), the main underlying conditions were steroid-treated chronic obstructive pulmonary disease, asthma, rheumatoid arthritis, giant-cell arteritis, and microvascular disorders; 10 patients were recipients of solid-organ transplants, and 1 patient was seropositive for human immunodeficiency virus. The distribution of proven and probable invasive aspergillosis was similar for neutropenic and nonneutropenic patients. The mortality rate was 71.5% overall and was significantly higher among nonneutropenic patients than among neutropenic patients (89% vs. 60%; P<.05). Compared with neutropenic patients, nonneutropenic patients were significantly less likely to have symptoms of invasive aspergillosis and more likely to have frequent intercurrent pneumonia due to another microorganism. The sensitivity of mycological examination of bronchoalveolar lavage fluid specimens was higher for nonneutropenic patients than for neutropenic patients (85% vs. 58%; P<.05), whereas the sensitivity of antigenemia was the same for the 2 populations (65% vs. 64%). Findings on thoracic computed tomographs were similar, except that segmental areas of consolidation occurred more frequently among neutropenic patients. CONCLUSION: This survey at a whole institution underlines the high number of cases of invasive aspergillosis among nonneutropenic patients, with an overall mortality rate that was significantly higher than that for neutropenic patients.

Adolescent↗
PubMed2006

C4d: a marker for hepatic transplant rejection.

BACKGROUND: Acute rejection is still a common complication of hepatic transplantation. The diagnosis, based on the histological examination of the graft, may be difficult to confirm in the setting of combined hepatitis C virus infection. The presence of C4d in the portal capillaries could facilitate differentiation between acute rejection and relapsed hepatitis C. The deposit of C4d provides evidence of activation of humoral immunity. To attempt to confirm this hypothesis, we searched for the presence of C4d in posttransplant hepatic biopsies. METHODS: Thirty-six biopsies from 34 patients were analyzed retrospectively. The samples had been requested for one of the following reasons: suspected rejection, relapsed hepatitis C infection, or systematic check-up 1 year after the transplant. RESULTS: C4d expression was common in biopsies classified as acute rejection (33%) and chronic rejection (100%). C4d was never detected in the event of recurrent hepatitis C infection without rejection. CONCLUSION: These results, which are comparable to recently published data, give credence to the theory that C4d could be used as a marker for rejection following hepatic transplantation.

Acute Disease↗
PubMed2003

Prediction of mesiodistal canine and premolar tooth width in a sample of Peruvian adolescents.

OBJECTIVES: To compare the predicted tooth width measurements of permanent canine and premolars from Tanaka-Johnston regression equations and Moyers probability tables with the in situ measurements in a sample of Peruvian adolescents. DESIGN: Cross-sectional. SETTING AND SAMPLE POPULATION: Trujillo, Peru; 248 dental casts were measured using a sliding caliper with a Vernier scale rounded to 0.1 mm. RESULTS: Tanaka-Johnston regression equations were not precise, except for the upper arch in the male sample. For females, the Moyers 95th percentile in the upper arch and the 65th percentile in the lower arch predicted the sum precisely. For males, the Moyers 65th percentile for the lower arch predicted the sum precisely, but none of the Moyers percentiles provided precise prediction in the upper arch. CONCLUSIONS: Using tooth width prediction methods from a different racial origin could create an under- or overestimation of the actual combined canine and premolar tooth width, although their clinical significance is disputable.

Adolescent↗
PubMed2002

Severe pneumonia due to Legionella pneumophila: prognostic factors, impact of delayed appropriate antimicrobial therapy.

OBJECTIVE: To compare the outcome of patients with severe Legionella pneumonia (LP) according to the presence or absence of prognostic factors currently reported in the literature and delays in initiating fluoroquinolones and macrolides. DESIGN: Retrospective clinical investigation. SETTING: Intensive care unit (ICU) of an university hospital. PATIENTS: Forty-three consecutive cases with no previous treatment with a macrolide or a fluoroquinolone. MEASUREMENTS AND MAIN RESULTS: The 14 (33%) patients who died of LP were compared with the 29 survivors. Thirty-eight patients (88%) received a fluoroquinolone in combination with a macrolide agent, two patients erythromycin alone and three ofloxacin alone. In univariate analysis, SAPS II more than 46 ( p=0.006) and intubation requirement ( p=0.012) were associated with a higher mortality whereas the administration of fluoroquinolones ( p=0.011) or erythromycin ( p=0.044) within 8 h of arrival on the ICU was associated with better survival. By logistic regression analysis, SAPS II score more than 46 [odds ratio (OR) 8.69; 95% confidence interval (CI) 1.15-66.7; p=0.036], duration of symptoms prior to ICU admission longer than 5 days (OR 7.46; 95% CI 1.17-47.6) were independent risk factors for death. Fluoroquinolone administration within 8 h of ICU arrival (OR 0.16; 95% CI 0.03-0.96; p=0.035) was associated with a reduced mortality. CONCLUSIONS: SAPS II score higher than 46, duration of symptoms prior to ICU admission longer than 5 days and intubation were associated with increased mortality. Initiation of fluoroquinolone therapy within 8 h of ICU admission significantly reduced mortality.

APACHE↗
PubMed2001

Persistence of both peripheral and non-peripheral corneodesmosomes in the upper stratum corneum of winter xerosis skin versus only peripheral in normal skin.

To understand the biochemical abnormalities that underlie the reduced desquamation observed in dry skin, we analyzed corneodesmosome degradation in normal and winter xerosis skin. Western blotting of total proteins from corneocytes obtained by varnish-strippings from the legs of 56 volunteers with normal (26) or xerotic (30) skin was performed using antibodies specific for (corneo)desmosome proteins. In the whole population, the amounts of desmoglein 1 and plakoglobin were found to be correlated, but were not related to the amounts of corneodesmosin. This suggests simultaneous proteolysis for the former proteins differing from that of corneodesmosin. Neither entire desmoplakins nor any proteolysis-derived fragments were detected. The amounts of corneodesmosin, desmoglein 1, and plakoglobin detected were found to be significantly higher in xerotic compared with normal skin extracts. Conventional and freeze-fracture electron microscopy showed the absence of nonperipheral corneodesmosomes in the upper stratum corneum of normal skin but the presence of a significant number of these structures in the same layer of winter xerosis skin. These results provide a more precise description of the proteolysis of corneodesmosome components in the upper cornified layer of the epidermis. They support previous studies demonstrating the importance of corneodesmosome degradation in desquamation and reveal that the nonperipheral corneodesmosomes, which are totally degraded during maturation of the stratum corneum in normal skin, persist in winter xerosis, probably leading to abnormal desquamation.

Adult↗
PubMed2000

Procalcitonin: a valuable indicator of infection in a medical ICU?

OBJECTIVE: To assess the use of procalcitonin (PCT) for the diagnosis of infection in a medical ICU. DESIGN: Prospective, observational study. PATIENTS: Seventy-seven infected patients and 24 patients with systemic inflammatory response syndrome (SIRS) due to other causes. Seventy-five patients could be classified into sepsis (n = 24), severe sepsis (n = 27) and septic shock (n = 24), and 20 SIRS patients remained free from infection during the study. Plasma PCT and C-reactive protein (CRP) levels were evaluated within 48 h of admission (day 0), at day 2 and day 4. RESULTS: As compared with SIRS, PCT and CRP levels at day 0 were higher in infected patients, regardless of the severity of sepsis (25.2 +/- 54.2 ng/ml vs 4.8 +/- 8.7 ng/ml; 159 +/- 92 mg/l vs 71 +/- 58 mg/l, respectively). At cut-off values of 2 ng/ml (PCT) and 100 mg/l (CRP), sensitivity and specificity were 65% and 70% (PCT), 74% and 74% (CRP). PCT and CRP levels were significantly more elevated in septic shock (38.5 +/- 59.1 ng/ml and 173 +/- 98 mg/l) than in SIRS (3.8 +/- 6.9 ng/ml and 70 +/- 48 mg/l), sepsis (1.3 +/- 2.7 ng/ml and 98 +/- 76 mg/l) and severe sepsis (9.1 +/- 18. 2 ng/ml and 145 +/- 70 mg/l) (all p = 0.005). CRP, but not PCT, levels were more elevated in severe sepsis than in SIRS (p<0.0001). Higher PCT levels in the patients with four dysfunctional organs and higher PCT and CRP levels in nonsurvivors may only reflect the marked inflammatory response to septic shock. CONCLUSION: In this study, PCT and CRP had poor sensitivity and specificity for the diagnosis of infection. PCT did not clearly discriminate SIRS from sepsis or severe sepsis.

Analysis of Variance↗
PubMed2000

[Cryptococcal meningitis associated with chronic lymphocytic leukemia: a case report. Review of the literature].

INTRODUCTION: The authors report the occurrence of a cryptococcal meningitis in a patient treated by corticosteroids and polychemotherapy for a chronic lymphocytic leukemia. EXEGESIS: A 63-year-old man with chronic lymphocytic leukemia was sent to hospital because of impaired condition with fever. Neurological disorders appeared. Cryptococcal meningitis was diagnosed. Under treatment, the outcome was favorable. CONCLUSION: This paper highlights the feature of this infection most likely underestimated in HIV-seronegative patients and the need to a priori consider this diagnosis.

Diagnosis, Differential↗
PubMed1999

Trial of dexamethasone treatment for severe bacterial meningitis in adults. Adult Meningitis Steroid Group.

OBJECTIVE: To evaluate the clinical benefit of early adjunctive dexamethasone therapy for severe bacterial meningitis in adults. DESIGN: Multicenter, double-blind, randomized trial initiated in emergency or intensive care units in France and Switzerland. Within 3 h after initiation of an aminopenicillin therapy, patients received dexamethasone (10 mg q.i.d.) or placebo for 3 days. The primary end-point was the rate of patients cured without any neurologic sequelae on day 30. RESULTS: Sixty patients were enrolled, predominantly with a severe form since 85% required ICU stay and 43% mechanical ventilation. Streptococcus pneumoniae accounted for 31 cases and Neisseria meningitidis for 18 cases. The study had to be stopped prematurely because of a new national recommendation of experts to use third generation cephalosporin and vancomycin as a result of the increasing rate of penicillin-resistant S. pneumoniae in France. After the third sequential analysis by the triangular statistical test, the difference of rate of cured patients without any neurologic sequelae was not statistically significant (p = 0.0711) between the dexamethasone group (74.2%; n = 31) and the placebo group (51.7%; n = 29). Furthermore, the former group was younger and less sick at inclusion. CONCLUSION: Bacterial meningitis is still a severe disease in adults, since the overall observed rate of death or severe neurologic sequelae was 26.7%. The reported data are inconclusive regarding a systematic use of dexamethasone as an adjunctive therapy for bacterial meningitis in adults. Moreover this treatment impairs antibiotic penetration into the cerebrospinal fluid (CSF) that can lead to therapeutic failure, particularly in areas with high or increasing rates of penicillin-resistant S. pneumoniae.

Adult↗
PubMed1999

Pacemaker lead infection: echocardiographic features, management, and outcome.

OBJECTIVE: To compare transthoracic and transoesophageal echocardiography (TTE, TOE) in patients with permanent pacemaker lead infection and to evaluate the safety of medical extraction in cases of large vegetations. METHODS: TTE and TOE were performed in 23 patients with definite pacemaker lead infection. Seventeen patients without previous infection served as a TOE reference for non-infected leads. RESULTS: TTE was positive in seven cases (30%) whereas with TOE three different types of vegetations attached to the leads were visualised in 21 of the 23 cases (91%). Of the 20 patients with vegetations and lead culture, 17 (85%) had bacteriologically active infection. Left sided valvar endocarditis was diagnosed in two patients. In the control group, strands were visualised by TOE in five patients, and vegetations in none. Medical extraction of vegetations >/= 10 mm was performed in 12 patients and was successful in nine (75%) without clinical pulmonary embolism. After 31.2 (19.1) months of follow up (mean (SD)), all patients except one were cured of infection; three died from other causes. CONCLUSIONS: Combined with bacteriological data, vegetations seen on TOE strongly suggest pacemaker lead infection. Normal TTE examinations do not exclude this diagnosis because of its poor sensitivity. Medical extraction of even large vegetations appeared to be safe.

Adult↗
PubMed1998

Acute respiratory failure caused by secondary alveolar proteinosis in a patient with acute myeloid leukemia: a case report.

Pulmonary alvelolar proteinosis (PAP) is a rare cause of chronic respiratory failure due to progressive alveolar accumulation of a periodic acid-schiff (PAS) positive proteinaceous material. In some cases, the rapid accumulation of intra-alveolar material leads to acute respiratory failure (ARF). We report the causative role of secondary PAP in the case of a 26-year-old man with acute myeloid leukemia who developed fever, increased serum lactate dehydrogenase level and ARF, and required mechanical ventilation. The diagnosis of PAP was established by the examination of material obtained by bronchoalveolar lavage (BAL). Respiratory improvement occurred several days after the patient had recovered from neutropenia. This report underlines the importance of the early diagnosis of PAP as a potential cause of ARF in leukemic patients. Adequate stain on BAL fluid provides the diagnosis and avoids repeated invasive procedures and inappropriate treatments.

Acute Disease↗
PubMed1997

Dimerization of Cdc25p, the guanine-nucleotide exchange factor for Ras from Saccharomyces cerevisiae, and its interaction with Sdc25p.

The oligomerization state of Cdc25p, the guanine nucleotide exchange factor for ras from yeast, was analyzed using different complementary approaches. The two-hybrid system showed that the C-terminal part of Cdc25p (Cdc25-Ct) can interact with itself but also with Sdc25p-Ct, the corresponding part of Sdc25p, the other guanine exchange factor from yeast. The homotropic interaction of Cdc25p-Ct has been confirmed in yeast using immunoprecipitation experiments with epitope-tagged and beta-galactosidase-fused polypeptides. No other component was required for this interaction, since dimerization was shown to occur with material synthesized in vitro. The size of Cdc25-Ct produced in Escherichia coli has been directly measured on gel filtration columns and corresponds to a dimer. The dimerization domain is localized in the same part of the molecule as the catalytic domain and the portion responsible for membrane localization. The biological relevance of dimerization is still an open question, however by allowing heterodimerization with Sdc25p it could permit a more complex combinatorial regulation of ras in yeast.

Binding Sites↗
PubMed1997

Effects of epinephrine on right ventricular function in patients with severe septic shock and right ventricular failure: a preliminary descriptive study.

OBJECTIVE: To recognize patients with unresponsive septic shock and right ventricular (RV) failure and to evaluate the effects of epinephrine on RV performance in these patients. DESIGN: Prospective descriptive study. SETTING: Medical intensive care unit. SUBJECTS: 14 consecutive patients in septic shock unresponsive to fluid loading, dopamine, and dobutamine. INTERVENTIONS: Evaluation of RV function by thermodilution with a pulmonary artery catheter equipped with a rapid-response thermistor. Measurements were obtained before and during epinephrine infusion to achieve a systolic arterial pressure > or = 90 mmHg or a mean arterial pressure (MAP) > or = 70 mmHg. RESULTS: At the time of inclusion in the study the hemodynamic pattern in the 14 patients was as follows: (MAP) 58 +/- 14 mmHg, systemic vascular resistance (SVR) 1046 +/- 437 dyne.s.cm-5.m-2, pulmonary artery occlusion pressure (PAOP) 14 +/- 4 mmHg, mean pulmonary artery pressure (MPAP) 24 +/- 4 mmHg, right arterial pressure (RAP) 11 +/- 4 mmHg, cardiac index (CI) 4 +/- 1.7 l/min per m2. During epinephrine infusion, MAP, CI and stroke volume index (SVI) were increased (27%, p < 0.01; 20%, p < 0.01; 15%, p < 0.05, respectively). There was no change in PAOP, SVR or heart rate. Seven patients (group A) had marked RV failure defined by both RV dilation [RV end-diastolic volume index (RVEDVI) > 92 ml/m2] and low RV ejection factor (RVEF) (< 52%) and 7 did not (group B). Group A had a lower baseline RVEF than group B (24 +/- 7 vs 45 +/- 9%, p < 0.05), a higher RVEDVI (134 +/- 28 vs 79 +/- 17 ml/ m2, p < 0.01), and a higher RVES (systolic) VI (103 +/- 30 vs 43 +/- 11 ml/ m2, p < 0.01). The other hemodynamics, especially RAP and RV stroke work index (RVSWI) were no different in the two groups and did not predict RV dysfunction. In group A, epinephrine infusion improved RVEF (25%, p < 0.05) by a reduction in RVESVI (-8%, p < 0.05) without any change in RVEDVI or in RAP, in spite of a rise in MPAP (11%, p < 0.05). A rise in RVSWI (76%, p < 0.05), SVI (23%, p < 0.05), and CI (24%, p < 0.05) was also achieved. An upward vertical shift of the Frank-Starling relationship RVSWI/ RVEDVI and an upward shift to the left of the pressure volume relationship pulmonary artery peak pressure/RVESVI was observed only in the group with RV failure following treatment with epinephrine. In group B (without RV failure), RV parameters were not modified by epinephrine. CONCLUSION: In patients with severe septic shock, RV dysfunction was identified by the use of an RVEF pulmonary artery catheter and was improved by epinephrine by means of an improvement in RV contractility.

Adult↗
PubMed1996

Calcium free hemodialysis: experience in the treatment of 33 patients with severe hypercalcemia.

OBJECTIVE: To assess the efficacy, adverse effects and relevance of calcium-free hemodialysis (CFHD) in the treatment of major hypercalcemia. DESIGN: Retrospective chart review. SETTING: Medical ICU. PATIENTS: All patients admitted over a 9-year period for hypercalcemia requiring urgent treatment and who underwent hemodialysis. INTERVENTIONS: CFHD with an acetate dialysate. MAIN RESULTS: Thirty-three patients with severe hypercalcemia from various etiologies received CFHD. Marked and rapid decrease of serum total calcium was obtained during all sessions (mean decrease: 1.71 +/- 0.54 mmol/l). Calcium rebound within 24 h after CFHD was observed in all evaluable cases (1 +/- 0.45 mmol/l; mean delay 13.7 +/- 5.8 h). Adverse cardiovascular effects occurred in 17 of 48 sessions (35%) and in 13 of 30 evaluable patients (43%). CONCLUSIONS: Adverse effects are frequent during CFHD. After correction of hypovolemia, its use should be restricted to patients with severe clinical symptoms or advanced renal impairment.

Adult↗
PubMed1996

[200 first hepatic transplantation at the Rennes University Hospital].

UNLABELLED: From 21st of april 1978 to 1st september 1994, 200 liver transplantations in 172 patients were performed in the Medical Center of University of Rennes. Three patients had a liver and kidney transplant. 26 patients received a second transplant (13%) and 2 patients a third transplant (1%). There were 110 males and 62 females with a mean age of 43.7 years (range 17 months-66 years). The indications of transplantations were the following: 22 fulminant hepatitis (12%), 104 cirrhosis (60.5%), including 41 alcoholic cirrhosis (24%), 21 post-hepatitis B cirrhosis (12.2%), 24 post-hepatitis C cirrhosis (14%), 6 autoimmune cirrhosis, 7 primary biliary cirrhosis (4%), 21 non A non B cirrhosis (12.9%), 3 undetermined cirrhosis. Thirty one patients had a liver transplantation for cancer. The other indications were 5 sclerosing cholangitis and 2 atresia of the biliary tract. 45% of the patients had an uneventful postoperative course. In hospital mortality rate is related to the indication and Child Pugh classification in cirrhotic patients. The vascular surgical complications were 8.5%, biliary complications 6.1%, intra-abdominal infection 9.2%, intra-abdominal bleeding 5.5%. The rate of reoperation was 18.5%. 23 re-transplantations were performed in emergency and 6 electively (one from outside). The overall survival of patients from 1978 to 1994, including the patients before cyclosporine era, the use of extracorporeal circulation, the preservation with Wisconsin solutions and with main indications for cancer was 69% at 1 year and 59% at 5 years. After 1988, the overall patient survival was 75% at 1 year and 70% at 5 years. The graft and patient survival is mainly related to the indications. In fulminant and subfulminant hepatitis, the quality of the graft was preferred as often as possible. The actuarial graft survival at 1 year, 3 years and 5 years was respectively 75%, 70.45% and 70.45%. The actuarial patient survival was 77.3%, 72.5% and 72.5%. In liver transplantation for cancer, the actuarial patient survival at 1 year, 3 years and 5 years is respectively 55%, 32% and 23.5%. 5 patients are alive and well at 5 years, including a patient who underwent a Cluster operation for Klatskin tumor. In post-hepatitis cirrhosis, the patient actuarial survival at 1 year, 3 years and 5 years was 79%, 76.5% and 76.5% and in alcoholic cirrhosis 75%, 72% and 72%. The actuarial survival is closely related to Child Pugh Classification (at one year Child A 87%, Child B 72.4%, Child C 58%). CONCLUSION: in this series of the first 200 liver transplants at the University of Rennes Medical Center, graft and patient survival depends on the evolution of the surgical technic but it is also closely related to the indication. In fulminant hepatitis, the quality of the graft (without incompatible graft, if possible) should permit to avoid retransplantation and to obtain results closely to the elective transplantation. Liver transplantation for cancer should be restricted. In cirrhosis, results are depending upon Child Pugh classification. The conclusions of Paris consensus conference should be followed. The limited number of donor livers call for the "priorization" (T.E. Starzl) favoring those patients who will benefit most, i.e., patients with the most serious conditions and the poorest short term vital prognosis.

Adolescent↗
PubMed1996

["De novo" cancer after organ transplantation].

From March 1972 to 1st of January 1996, 804 kidney, liver and pancreas transplants were performed in 690 patients. 39 post transplant cancers occurred in 27 patients. 21 skin tumors (15 squamous cell carcinoma, 4 basocellular carcinomas, 1 squamous carcinoma, 1 melanoma), 4 squamous cancers (anus, esophagus, tongue, and parotid), 4 post-transplant lymphoproliferative disorders, 1 non-Hodgkin's lymphoma T, 4 gynecological tumors (breast, ovarian peritoneal carcinomatosis, 2 uterine cervix cancers), 4 miscellaneous tumors (larynx, right colon, brain, prostate, own kidney). 14 patients died (14/27: 52%). Post transplant de novo cancers are a major risk in transplant patients These cancers are mainly represented by skin tumors and lymphomas. Skin cancers are mainly spinocellular and occur in the areas which are exposed to the sun. Post transplant lymphoproliferative disorders are very close to Burkitt's lymphoma, they produced B lymphocyte proliferation due to the reduction of the control of T lymphocytes and induced by Epstein-Barr virus. They can disappear with the diminution of immunosuppression.

Adult↗
PubMed1995

X-ray structure and catalytic mechanism of lobster enolase.

Enolase prepared from lobster tail muscle yielded trigonal crystals with one 47 kDa subunit per asymmetric unit. X-ray data were collected on the apoenzyme at 2.4 A resolution and on a complex with Mn2+ and the inhibitor phosphoglycolate at 2.2 A resolution. The corresponding cDNA was amplified from a library of lobster muscle cDNA, and a sequence corresponding to residues 27-398 was determined. It is highly homologous to other enolases, including yeast enolase for which an X-ray structure is available. Yeast enolase was used as a starting point for crystallographic refinement, which led to models of lobster enolase having R-factors below 22% and good stereochemistry. These models are very similar to yeast enolase; they have the same fold with a beta 3 alpha 4 N-terminal domain followed by an atypical alpha/beta barrel. Lobster apoenolase and the ternary complex differ only in the position of three mobile loops. In the complex, a single Mn2+ ion is seen ligated to three carboxylates and three water molecules. Phosphoglycolate binds near, but not directly to, the metal. His 157, which belongs to one of the mobile loops, is in contact with the C2 atom of the ligand. A water molecule hydrogen-bonds to the carboxylate of the ligand and to those of Glu 166 and Glu 209. We suggest that His 157 is the base that abstracts the C2H proton, whereas the water molecule is part of a proton relay system keeping the substrate in the carboxylic acid form where the pKa of the C2H group is low enough for proton transfer to His 157. The resulting catalytic mechanism is different from those proposed on the basis of the yeast enzyme X-ray structures, but it fits with earlier biochemical and spectroscopic data.

Amino Acid Sequence↗