bluuebunny/crossref_metadata_2025 huggingface dataset:
Enteric‐coated mycophenolate sodium delivers bioequivalent MPA exposure compared with mycophenolate mofetil
Authors: Arns Wolfgang , Breuer Stephan , Choudhury Somesh , Taccard Guy , Lee James , Binder Vera , Roettele Jürgen , Schmouder Robert
Published: March 2005

Abstract: Mycophenolic acid (MPA), the active moiety of mycophenolate mofetil (MMF), is routinely used as an adjunct immunosuppressant therapy in renal transplantation. Although highly effective, MMF therapy is associated with significant gastrointestinal adverse effects. Enteric‐coated mycophenolate sodium (EC‐MPS) is an advanced formulation delivering MPA. The enteric coat dissolves at pH > 5 allowing for MPA delivery in the small intestine. A single‐center, open‐label, randomized, three‐way crossover study of 24 stable Caucasian renal transplant patients receiving cyclosporine‐based immunosuppression, compared the relative bioavailability of two EC‐MPS doses (640 and 720 mg) with MMF (1000 mg). Both EC‐MPS doses delivered bioequivalent mean MPA exposure (AUC0−∞) compared with 1000 mg MMF: 60.7 μg h/mL for 640 mg EC‐MPS, 66.5 μg h/mL for 720 mg EC‐MPS, and 63.7 μg h/mL for 1000 mg MMF. Mediantmaxwas significantly delayed for both EC‐MPS doses compared with MMF (2.0 h vs. 0.75 h, respectively; p < 0.01), consistent with a functional enteric coating of EC‐MPS. Furthermore, both EC‐MPS doses were bioequivalent to 1000 mg MMF forAUCandCmaxfor mycophenolic acid glucuronide. All three treatments were well tolerated. The EC‐MPS 720 mg dose most closely approximated the MPA exposure of 1000 mg MMF and was selected for subsequent phase III studies.
Outflow block secondary to stenosis of the inferior vena cava following living‐donor liver transplantation?
Authors: Mizuno Shugo , Yokoi Hajime , Yamagiwa Kentaro , Tabata Masami , Isaji Shuji , Yamakado Koichiro , Takeda Kan , Uemoto Shinji
Published: March 2005

Abstract:  Although it is well known that outflow block is caused by stenosis or occlusion of hepatic vein anastomoses following living donor liver transplantation (LDLT), there have been few reports on inferior vena cava (IVC) stenosis following LDLT. In this paper, we report two cases of IVC stenosis and hepatic vein outflow block following right hepatic LDLT in the absence of stenosis of any of the anastomoses. Both patients presented with liver dysfunction, an ascitic fluid volume of approximately 2000 mL, and congestion in their biopsy specimens, and venocavography demonstrated IVC stenosis with gradients of more than 10 mmHg in patients with a dominant inferior right hepatic vein (IRHV) anastomosis. After a Gianturco expandable metallic stent successfully implanted in the IVC, the patient's liver function recovered and the volume of ascitic fluid decreased. The pathogenesis of hepatic vein outflow block secondary to IVC stenosis following LDLT may involve the anastomosis with the IRHV, which is the dominant draining vein of the graft and larger than the RHV, caudal to the IVC stenosis and a significant IVC pressure gradient that results in increased IRHV pressure. In conclusion, it is important to include hepatic vein outflow block in the differential diagnosis when patients who have undergone right hepatic LDLT in which anastomosis of the large IRHV has been performed develop manifestations of liver dysfunction.
The long‐term outcome of tacrolimus in cadaveric kidney transplantation from non‐heart beating donors
Authors: Fukuhara Nobuyuki , Ono Yoshinari , Hattori Ryohei , Nishiyama Naoki , Yamada Shin , Kamihira Osamu , Kinukawa Tsuneo , Ohshima Shinichi
Published: March 2005

Abstract:  Tacrolimus (Tac), developed in 1990, has been applied as an immunosuppressive agent for liver, heart, and kidney transplantation and is known to have more powerful immunosuppressive effects than cyclosporine (CyA). To evaluate the efficacy of Tac in cadaveric kidney transplants from non‐heart beating donors, we present the long‐term outcome of patients receiving kidneys with ischemic damage, and compared it with that of CyA. Between July 1990 and December 2000, 55 patients with end‐stage renal disease received kidneys from non‐heart beating donors (Maastrichy category 3) and were treated with Tac and steroid immunosuppressive therapy. During the same period, we also performed 137 non‐heart beating cadaveric renal transplants treated with CyA‐based immunosuppressive therapy. The patient survival rate was 98% at 1 yr and 96% at 3–10 yr in the Tac group, and 97% at 1–3 yr, 93% at 5 yr and 85% at 10 yr in the CyA group. The graft survival rate was 91% at 1 yr, 80% at 3 yr, 63% at 5 yr and 34% at 10 yr in the Tac group, and 88% at 1 yr, 75% at 3 yr, 63% at 5 yr and 49% at 10 yr in the CyA group. There was no significant difference in either patient or graft survival rates between the two groups. Acute early rejection in the Tac group was less than that in the CyA group but acute tubular necrosis was the same in both groups. This indicates that Tac is available for cadaveric kidney transplants from non‐heart beating donors. In conclusion, Tac is available as an immunosuppressive agent even for kidney transplants from non‐heart beating donors.
The effect of sirolimus on sex hormone levels of male renal transplant recipients
Authors: Lee Suji , Coco Maria , Greenstein Stuart M. , Schechner Richard S. , Tellis Vivian A. , Glicklich Daniel G.
Published: March 2005

Abstract:  Background:  It is unclear whether sirolimus, a newer immunosuppressive agent, widely used in renal transplantation, affects male sex hormone levels or sexual function.

Methods:  Sex hormone profiles in male renal transplant recipients were obtained and compared between a sirolimus‐treated group and a group not on sirolimus in a cross‐sectional study. Both groups also completed a sexual dysfunction questionnaire.

Results:  Sixty‐six subjects were evaluated, 32 in the sirolimus group and 34 in the control group. Total testosterone level was significantly lower in the sirolimus group than the control group (393.3 ± 188 vs. 537.4 ±232 pg/mL; p = 0.08) while follicle stimulating hormone and luteinizing hormone levels were significantly higher in the sirolimus group (12.8 ± 14 vs. 6.0 ± 5, p = 0.013; 10.9 ± 14 vs. 4.7 ± 4, p = 0.018, respectively). There was a significant negative correlation between 24‐h sirolimus trough and total testosterone levels (p < 0.03). By multiple regression analysis, use of sirolimus was independently associated with decreased total testosterone level. There was no significant difference in subjective sexual dysfunction as assessed by questionnaire scores between the two groups. There was no correlation between questionnaire scores and total testosterone level.

Conclusion:  Sirolimus is associated with decreased total testosterone levels in male renal transplant recipients. It is unclear whether sirolimus may affect other aspects of sexual function.
Feasibility of salvage liver transplantation for patients with recurrent hepatocellular carcinoma
Authors: Hu Rey‐Heng , Ho Ming‐Chi , Wu Yao‐Ming , Yu Seng‐Chang , Lee Po‐Huang
Published: March 2005

Abstract:  Background:  Recurrence is the most frequent cause of treatment failure after hepatocellular carcinoma (HCC) resection. Salvage liver transplantation is an alternative treatment for recurrent HCC. The transplantability for patients with recurrent HCC has not been well studied.

Study design:  This study sought to determine how many patients with recurrent HCC are still candidates for liver transplantation, and to ascertain the possible time from HCC recurrence to the loss of transplantability. In an university hospital setting, 154 of the 252 patients receiving primary HCC resection, from January 1992 through December 1996, had recurrence and were analyzed. The mean follow‐up time was 6 years. Among the 154 patients, 74 patients (group 1) were not eligible for liver transplantation according to the Milan criteria, while 80 patients were eligible (group 2). Demographic characteristics of both groups were compared and the curve of transplantability was calculated.

Results:  When compared with group 1 patients, group 2 patients displayed more cirrhosis (p = 0.007), lower pTNM stage (p = 0.004), were older (p = 0.004), presented with smaller tumors (p < 0.001), and displayed a longer disease‐free interval (p < 0.001). In group 1, only 47% (35/74) patients were eligible for liver transplantation at the time of index hepatectomy, in contrast to 84% (67/80) in the group 2 patients, p < 0.001. The median time from HCC recurrence to the time they were no longer transplantable was 38 months. The total time from the index HCC resection to the time of loss of transplantability was 83 months.

Conclusion:  In a cohort of patients after resection for their primary HCC, 33% patients had no recurrence and were not in need for liver transplantation in a mean follow‐up of 72 months. About 52% of the patients with recurrent HCC still meet the criteria for liver transplantation. For patients with some certain characteristics, resection of the primary HCC may postpone the time of liver transplantation and prolong the time in which a suitable donor searched, while primary liver transplantation may be considered for those patients with factors of low transplantability after recurrence.
Tobacco and alcohol use in lung transplant candidates and recipients
Authors: Evon Donna M , Burker Eileen J , Sedway Jan A , Cicale R , Davis K , Egan T.
Published: March 2005

Abstract:  Tobacco and alcohol use among lung transplant candidates and recipients is unknown. Our first goal was to describe tobacco and alcohol use before and after lung transplant in patients with cystic fibrosis (CF) and other pulmonary diseases (non‐CF). Our second goal was to determine whether demographic variables, depression, anxiety and social support predicted tobacco and alcohol use. Self‐report data from transplant candidates and recipients, and transplant nurse coordinator ratings of post‐transplant smoking and drinking were utilized. Data from two samples were analyzed. Sample 1 comprised 219 patients being evaluated for lung transplant, and sample 2 comprised 45 transplant recipients who were 1–7 yrs post‐transplant. The results from analyzing sample 1 indicated that 72% of non‐CF patients and 16% of CF patients had a history of smoking cigarettes, and the majority of patients in both groups had consumed alcohol in the past. For CF patients, past smoking was related to higher depression scores, and past drinking was related to higher education and lower social support. For non‐CF patients, a history of smoking was associated with being Caucasian and older. For CF patients, a history of drinking was associated with being older and less depressed, and for non‐CF patients a history of drinking was associated with higher education and lower social support. Post‐transplant 100% of recipients reported abstinence from tobacco, and over 60% reported abstinence from alcohol. Transplant coordinator ratings corroborated that no transplant recipients were using tobacco products or consuming alcohol in an excessive or problematic manner. For both groups, consuming alcohol after transplant was related to lower levels of social support. In conclusion, lung recipients remain abstinent from tobacco, and although over 30% of patients consume alcohol after transplant, it is not at problematic levels. Smoking and drinking behaviors were related to demographic variables, depression, and low social support.
Late anastomotic leaks in pancreas transplant recipients – clinical characteristics and predisposing factors
Authors: Nath Dilip S , Gruessner Angelika , Kandaswamy Raja , Gruessner Rainer W , Sutherland David ER , Humar Abhinav
Published: March 2005

Abstract:  Background:  Anastomotic leaks after pancreas transplants usually occur early in the postoperative course, but may also be seen late post‐transplant. We studied such leaks to determine predisposing factors, methods of management, and outcomes.

Results:  Between January 1, 1994 and December 31, 2002, a total of 25 pancreas transplant recipients at our institution experienced a late leak (defined as one occurring more than 3 months post‐transplant). We excluded recipients with an early leak or with a leak seen immediately after an enteric conversion. The mean recipient age was 40.3 yr; mean donor age, 31.3 yr. The category of transplant was as follows: simultaneous pancreas–kidney (n = 5, 20%), pancreas after kidney (n = 10, 40%), and pancreas transplant alone (n = 10, 40%). At the time of their leak, most recipients (n = 23, 92%) had bladder‐drained pancreas grafts; only two recipients (8%) had enteric‐drained grafts. The mean time from transplant to the late leak was 20.5 months (range = 3.5–74 months). A direct predisposing event or risk factor occurring in the 6 wk preceding leak diagnosis was identified in 10 (40%) of the recipients. Such events or risk factors included a biopsy‐proven episode of acute rejection (n = 4, 16%), a history of blunt abdominal trauma (n = 3, 12%), a recent episode of cytomegalovirus infection (n = 2, 8%), and obstructive uropathy from acute prostatitis (n = 1, 4%). Non‐operative or conservative care (Foley catheter placement with or without percutaneous abdominal drains) was the initial treatment in 14 (56%) of the recipients. Such care was successful in nine (64%) of the 14 recipients; the other five (36%) required surgical repair after failure of conservative care at a mean of 10 d after Foley catheter placement. Of the 25 recipients, 11 underwent surgery as their initial leak treatment: repair in nine and pancreatectomy because of severe peritonitis in two. After appropriate management (conservative or operative) of the initial leak, five (20%) of the 25 recipients had a recurrent leak; the mean length of time from initial leak to recurrent leak was 5.6 months. All five recipients with a recurrent leak ultimately required surgery.

Conclusions:  Late anastomotic leaks are not uncommon; they may be more common with bladder‐drained grafts. One‐third of the recipients with a late leak had experienced some obvious preceding event that predisposed to the leak. For two‐thirds of our stable recipients with bladder‐drained grafts, non‐operative treatment of the leak was successful.
Basiliximab lowers the cyclosporine therapeutic threshold in the early post‐kidney transplant period
Authors: Balbontin F , Kiberd B , Fraser A , Kiberd M , Lawen J
Published: March 2005

Abstract:  Early adequate cyclosporine exposure has been shown to predict low acute rejection rate in kidney transplantation. The aim of this study is to determine the importance of exceeding the early cyclosporine therapeutic exposure threshold with basiliximab induction. A retrospective analysis of 166 first cadaveric and non‐identical live donor transplant recipients treated with or without basiliximab induction, Neoral, mycophenolate mofetil and prednisone, was performed. Adequate exposure was defined as a 2‐h post‐Neoral dose cyclosporine level (C2) >1700 ng/mL at day 3. The primary outcome was acute rejection within the first 6 months. In the no basiliximab (control) group (n = 74), rejection occurred in 23% (17 of 74) of recipients and was strongly associated with low cyclosporine exposure on day 3. Acute rejection occurred in 38% (11 of 29) with C2 <1700 ng/mL compared with 13% (six of 45) with C2 ≥1700 ng/mL (p = 0.014). In the basiliximab group (n = 92), rejection occurred in only 11% (10 of 92) of recipients and did not correlate with cyclosporine exposure. Acute rejection occurred in 10% (four of 40) with C2 <1700 ng/mL compared with 12% (six of 52) with C2 ≥1700 ng/mL (p = 0.81). Therefore achieving cyclosporine therapeutic targets by day 3 may not be required when anti‐IL2 receptor antibody induction is used.
Therapeutic drug monitoring for everolimus in kidney transplantation using 12‐month exposure, efficacy, and safety data
Authors: Lorber Marc I , Ponticelli Claudio , Whelchel John , Mayer Hartmut W , Kovarik John , Li Yulan , Schmidli Heinz
Published: March 2005

Abstract:  The aims of the current study were to determine whether therapeutic drug monitoring (TDM) might benefit kidney transplant recipients receiving everolimus, and to establish dosage recommendations when everolimus is used in combination with cyclosporine and corticosteroids. The analysis was based on data from 779 patients enrolled in two 12‐month trials. Everolimus trough concentrations ≥3 ng/mL were associated with a reduced incidence in biopsy‐proven acute rejection (BPAR) in the first month (p = 0.0001) and the first 6 months (p = 0.0001), and reduced graft loss compared with lower concentrations (4% vs. 20%, respectively). By contrast, cyclosporine in the standard concentration range had no impact on BPAR within the same timeframes. Most patients receiving everolimus 1.5 or 3 mg/d achieved trough concentrations above the therapeutic threshold of 3 ng/mL, regardless of reductions in cyclosporine dose. TDM simulation showed that just two dose adjustments would achieve median everolimus trough values ≥3 ng/mL in 95% of patients during the first 6 months.

This investigation indicates that improved efficacy is likely when TDM is considered as an integral component of the immunosuppressive strategy of everolimus.
Urinary tract infections after renal transplantation: a retrospective review at two US transplant centers
Authors: Chuang Peale , Parikh Chirag R , Langone Anthony
Published: March 2005

Abstract: Urinary tract infections (UTIs) are the most common infectious complication following renal transplantation. Previous studies uniformly report that renal transplant recipients develop UTIs more often than the general population, but widely differ on how frequently UTIs occur after transplantation. These studies also disagree on the risk factors associated with developing post‐transplant UTIs, as well as the effect that UTIs may have on graft outcomes and patient mortality. We performed a retrospective cohort study including all the adult patients who received a renal transplant at two US transplant centers from January 1996 to December 2002 (500 patients). Two hundred and thirteen (43%) patients developed one or more post‐transplant UTIs over a mean follow‐up period of 42 months. Significant risk factors for post‐transplant UTIs were advanced age, female gender, reflux kidney disease, use of azathioprine and cadaveric donor. UTIs did not increase risk for renal graft loss, but were associated with increased mortality (3.5 odds ratio, 95% confidence interval 1.68–7.23). We conclude UTIs may be associated with an increased mortality risk in renal transplant recipients. Prevention of UTIs in high‐risk renal transplant patients or those with recurrent UTIs may possibly decrease post‐transplant mortality.
Airway cellular response to two different immunosuppressive regimens in lung transplant recipients
Authors: Slebos Dirk‐Jan , Kauffman Henk F , Koëter Gerard H , Verschuuren Erik AM , van der Bij Wim , Postma Dirkje S
Published: March 2005

Abstract:  A number of new immunosuppressive drugs have become available in transplant medicine. We investigated the effects of two different immunosuppressive protocols on bronchoalveolar lavage fluid cellular characteristics in 34 lung transplant recipients who were treated with anti‐thymocyte globulin induction therapy, cyclosporine, azathioprine (AZA), and prednisolone (regimen I), compared with 17 recipients receiving basiliximab induction, tacrolimus, AZA, and prednisolone (regimen II). We performed bronchoalveolar lavages between 15 and 40 d post‐transplantation, in stable clinical condition and no acute rejection, cytomegalovirus, and/or respiratory tract infection. The regimen II treatment was associated with a significantly lower percentage lavage fluid lymphocytes than with regimen I. The CD4/CD8 ratio was significantly higher with regimen II than with regimen I: 1.56 (range 0.41–2.16) and 0.33 (0.04–0.95) respectively; p < 0.001, mainly because of a lower percentage CD8+ cells with regimen II: 25% (12–51) vs. regimen I: 60% (34–77); p < 0.001. The percentage CD4+ CD25+ cells appeared lower with regimen II: 21% (10–88) vs. regimen I: 50% (0–87); p = 0.04. Overall survival was similar between the groups, whereas a beneficial trend in freedom of bronchiolitis obliterans syndrome was observed with regimen II. Airway lymphocyte subtypes are affected by the immunosuppressive protocol used. This observation should be taken into account when studying transplant recipients, and may contribute to our understanding of alloreactive airway disease.
Minimization of immunosuppression with thymoglobuline pre‐treatment and HCV recurrence in liver transplantation
Authors: Ruvo Nicola De , Cucchetti Alessandro , Lauro Augusto , Masetti Michele , Benedetto Fabrizio Di , Cautero Nicola , Barba Giuliano La , Dazzi Alessandro , Francesco Fabrizio Di , Molteni Gabriele , Romano Antonio , Ramacciato Giovanni , Risaliti Andrea , Pinna Antonio Daniele
Published: March 2005

Abstract:  Induction with thymoglobuline, a potent anti‐thymocyte polyclonal antibody, has been recently reported to allow minimization of postoperative immunosuppression in organ transplantation. The relationship with recurrence of hepatitis C virus (HCV) after liver transplantation (LTx) has never been investigated. We report here on the outcome in 22 HCV+ patients receiving thymoglobuline pre‐treatment and minimal immunosuppression after LTx. Patient survival and acute rejection rates were good, and remarkably low dosages and levels of immunosuppression were achieved with thymoglobuline, without exposing patients to an elevated risk of rejection. A progressive weaning of the primary immunosuppressor was also possible in the majority of patients without complications. The HCV recurrence rate was similar to what is reported in the literature, although lower HCV‐RNA viral loads were obtained with thymoglobuline, with a mild histologic course. Although our results need to be validated in large cohort studies, our experience shows that minimization of immunosuppression with thymoglobuline is effective in protecting against rejection and demonstrated a positive impact on HCV recurrence that deserves further investigation.
Should people who commit themselves to organ donation be granted preferred status to receive organ transplants?
Authors: Spital Aaron
Published: March 2005

Abstract:  Granting preferred status for transplantation to people who commit themselves to posthumous organ donation is an intriguing proposal designed to increase the pool of cadaveric organ donors. Under one version of this plan, all competent adults who had previously consented to having their organs removed and transplanted upon their deaths would be given priority to receive organs, should they ever need them, over potential recipients of equal need who had not agreed to donate. To see if this plan would be acceptable to the public, I contracted Harris Interactive to conduct a national telephone survey about this issue. One thousand fourteen adults living in the United States were queried. Fifty‐three percent of the respondents thought that people who agree to donate their organs after death should be granted priority to receive cadaveric organ transplants over those who do not agree to donate. Only 30% of the respondents would definitely oppose this plan. These data suggest that a pilot study of preferred status should be considered.
Purification and Properties of Two Forms of 6‐Phosphogluconate Dehydrogenase from Candida utilis
Authors: Rippa M. , Signorini M. , Pontremoli S.
Published: March 2005

Crude extracts of Candida utilis contain two types of 6‐phosphogluconate dehydrogenase. One can be obtained in the crystalline form and has already been described and studied. In the present paper the purification of the second one, together with the differences in the properties between the two purified proteins, is reported. The two types of enzyme have identical pH optimum, same Km for the substrates and same specificity. They differ in amino acid composition, molecular weight, electrophoretic mobility, stability to pH and heat treatment, sensitivity to chlorodinitrobenzene and proteolytic treatment. All evidence indicates a greater instability of the crystalline enzyme in respect to the non‐crystalline one and seems to exclude that the two forms of enzyme are an artefact due to the extraction or the purification procedures.
Zum Mechanismus der Ribonuclease‐Reaktion
Authors: Wieker H.‐J. , Witzel H.
Published: March 2005

The hydrolysis of cyclic 2′,3′‐cytidylic acid (Cp) and cyclic 2′,3′‐uridylic acid (Up) by panereatic ribonuclease (E.C.2.7.7.16) at pH 7 and 5.6 is activated by adenine, adenosine, cyclic 2′,3′‐adenylic acid, and adenylyl‐adenosine (ApA). The activation is reflected by parallel shifts in the kinetic parameters when expressed on a e/v—1/s‐diagram. The measured parameters k°=π·k+2 and K°=Φ·Km are increased by the same factor, i.e.Φ=π > 1 or 1.

Rate equations can be derived for an interaction of the modifier with either the substrate, the enzyme, or the enzyme‐substrate‐complex (ES), independent of any mechanistic concept. It is then possible to calculate the conditions pertaining to the relation Φ=π.

The first case, an interaction between the modifier and the substrate can be excluded. In the case of an interaction between the modifier and the enzyme or ES the rate equations if Φ=π require that k−1 and k+2 are equally influenced by the modifier. Thus both constants are coupled and associated with reactions of the same type.

Since the dissociation of the inhibitor 3′‐Cp from the enzyme as measured by relaxation times [21] is 103 times faster than the k+2 value in the reaction where the same 3′‐Cp is formed as the product, k+2 cannot be the dissociation of the product from the enzyme, but must be associated with a step involving bond exchange. Consequently k−1 must be associated with a step which also involves a bond exchange and is catalysed by the same principle. Both steps should therefore start from a common intermediate and lead alternatively either to the substrate (k−1) or to the product (k+2).

It can be further shown that k+1 must be associated with the complementary step to k−1, also involving bond exchange, and that a simple association‐dissociation‐equilibrium between enzyme and substrate (not involving covalent bond exchanges in the substrate) does not appear in the measurable kinetic parameters. Km therefore would not represent a dissociation constant in the sense of Michaelis‐Menten but rather the ratio of the rate constants for the breakdown and the formation of an intermediate which is stabilized by the enzyme.

The mathematical relations do not give any information as to the nature of the bonds exchanged or the type of catalysis. On the basis of the mechanism derived from other experiments in our previous investigations [1,3] it can be concluded now that the enzyme only induces a non‐rate‐limiting polarisation at the monoanionic phosphodiester group of the substrates. Binding would occur in a very fast non‐rate‐limiting step after the rate limiting base catalysed step when the dianionic intermediate has been formed.
Spectrométrie de masse de glycolipides
Authors: Senn M. , Ioneda T. , Pudles J. , Lederer E.
Published: March 2005

“Cord factors” are diesters of α,α‐trehalose produced by Mycobacteriae and Corynebacteriae. Saponification of the “cord factor” of Corynebacterium diphtheriae gives an equimolecular mixture of homologues of the saturated corynomycolic and of the unsaturated corynomycolenic acids (I and II, R = H). Máss spectrometry of their methyl esters confirms their structures (see Fig. 1, R = CH3).

The peracetylated cord factor (IV, a, b, c) gave very weak molecular ions at m/e 1630, 1632 and 1634 showing apparently that it is a mixture of the diesters having respectively two saturated, one saturated and one unsaturated, and two unsaturated acyl radicals. Strong peaks at m/e 809 and 807 are attributed to the oxonium ions (V a and V b).

These results as well as chemical degradations show that the “cord factor” of C. diphtheriae is a mixture of glycolipids (III a, b, c).
The Determination of the Order of Lysine‐containing
Authors: Perham R. N. , Jones G. M. T.
Published: March 2005

A new diagonal electrophoretic technique for determining the order of the lysine‐containing tryptic peptides of a protein is described. The protein is converted into its trifluoracetyl derivative, digested enzymatically (or chemically), and the resulting peptides separated by paper electrophoresis. The paper is then treated with ammonia vapour, which re‐exposes the ɛ‐amino groups of the lysine residues, and submitted to a second electrophoresis at right angles to the first direction. Peptides containing lysine residues, together with the N‐terminal peptide of the protein, are found to lie off a diagonal formed by all other peptides, whence they may be readily purified. A study of these peptides enables the order of the lysine‐containing tryptic peptides in the protein to be deduced.

The technique has been successfully tested with insulin.

When the method was applied to porcine pepsin, the four tryptic peptides isolated were easily ordered and the carboxyl‐terminal sequence of the protein shown to be Arg‐Gln‐Tyr‐Tyr‐Thr‐Val‐Phe‐Asp‐Arg‐Ala‐Asn‐Asn‐Lys‐Val‐Gly‐Leu‐Ala‐Pro‐Val‐Ala. The three basic amino acid residues in the molecule are thus found clustering towards the C‐terminus of the polypeptide chain.

A common ancestral gene for porcine pepsin and bovine (calf) rennin is suggested by the close homology between the C‐terminal sequences of the two proteins.
Interactions entre pigments et acides nucléiques
Authors: Ohba Y. , Fromageot P.
Published: March 2005

Luteoskyrine can be bound to nucleic acids in presence of Mg2+ ions. Two types of complexes are found. Complex I is made with single stranded nucleic acids containing purine bases such as denatured DNA, heated apyrimidinic acid, poly adenylic acid, poly inosinic acid or heated poly guanylic acid. Its visible spectrum is shifted towards shorter wavelengths compared to that of free luteoskyrine. Complex II is formed with double stranded nucleic acids or with single stranded ones deprived of purine bases such as a purinic acid, poly uridylic or poly cytidylic acid. The visible spectrum of complex II is shifted towards longer wavelengths with respect to that of free pigment. In complex I, one mole of luteoskyrine is associated to one atom of magnesium. Prolonged dialysis or heating does not dissociate the magnesium from the complex I but addition of EDTA does, with the simultaneous appearance of the free dye spectrum. Any purine residue in a polynucleotide is a potential site for complex I formation, but neither the nature of the purine (adenine or guanine) nor the nature of the sugar (ribose or deoxyribose) is relevant. However, the maximum amount of luteoskyrine bound as complex I by poly adenylic acid corresponds to a dye/purine ratio of 1/2. This ratio is somewhat larger with the denatured DNAs studied, being comprised between 1/1,2 and 1/1,7. It is suggested that this limit for complex I formation results from steric hindrance due to the size of the luteoskyrine molecule. Being bound to a given purine residue, a luteoskyrine molecule hinders the approach of another dye molecule to the adjacent purine residue but not to the one second next. According to this hypothesis, the maximum amount of complex I formed with given DNA can be calculated from the frequencies of purines sequences, and the predictions made correspond to the observed values. It is therefore likely that the stoechiometry of complex I corresponds to the association of one purine residue, one molecule of luteoskyrine and one atom of magnesium.

To be able to bind luteoskyrine and magnesium as a complex I, a purine‐containing oligo‐nucleotide has to have a certain minimum size of 5 to 6 nucleotides (at 20 °). This suggests that a certain conformation of the relevant purine nucleotide residue is required for the binding of luteoskyrine as complex I.
Carboxyl‐Terminal Region of Human and Bovine Erythrocyte Carbonic Anhydrases
Authors: Andersson B. , Göthe P. O. , Nilsson T. , Nyman P. O. , Strid L.
Published: March 2005

A methionine‐containing tryptic peptide from acetamidinated human carbonic anhydrase B has been isolated. This peptide has been shown to bridge a previously known carboxyl‐terminal fragment prepared by CNBr degradation with the rest of the enzyme molecule. Sequence studies on the methionine‐containing peptide have extended the previous knowledge of the carboxyl‐terminal sequence of the enzyme.

Corresponding bridge peptides from human carbonic anhydrase C and acetamidinated bovine carbonic anhydrase B have also been isolated and their amino acid compositions have been determined.
Études sur les fractions glucidiques de la trame fibreuse insoluble du stroma cornéen
Authors: Moczar E. , Robert L. , Moczar M.
Published: March 2005

Calf corneas were extracted with a buffer containing M CaCl2, 0.05 M Tris and 0.02 M citric acid, at pH 7.5. The residual stroma was digested successively by collagenase and pronase. The glycopeptides obtained were separated by gel filtration and high voltage electrophoresis. The sugar and amino acid content of the isolated glycopeptides was determined. Two types of sugar chains were detected: (a) chains with a more complicated structure, containing galactose, glucose, mannose and glucosamine; (b) disaccharidic and monosaccharidic side chains containing galactose and glucose or galactose alone and linked O‐glycosidically to the OH groups of hydroxylysine. The Hyl‐Gal‐Glc compound was isolated and identified with the compound isolated by Butler and Cunningham from calf skin collagen, by the study of its composition, thin layer chromatography and high voltage electrophoresis.

The stroma of the calf cornea contains about 4 times more hexoses in the small glycopeptides of type b (di‐ and monosaccharides) than in the higher molecular weight mannose‐containing chains.
Effect of Phenobarbital on the Conversion of Cholesterol to Taurocholic Acid
Authors: Einarsson K. , Johansson G.
Published: March 2005

The effect of administration of phenobarbital to rats on four different enzyme systems in the metabolic pathway from cholesterol to taurocholic acid, on the metabolism of androst‐4‐ene‐3,17‐dione, and on the oxidative demethylation of aminopyrine was studied in liver homogenates. In homogenates of liver from phenobarbital‐treated rats the extent of 7α‐hydroxylation of cholesterol and the conversion of cholest‐5‐ene‐3β,7α‐diol into 7α‐hydroxycholest‐4‐en‐3‐one were not significantly increased as compared to control rats. The 12α‐hydroxylation of 7α‐hydroxycholest‐4‐en‐3‐one was about 50% lower in phenobarbital‐treated rats than in control rats. The 7α‐hydroxylation of taurodeoxycholic acid was about twice as high in phenobarbital‐treated rats as in control rats. The conversion of androst‐4‐ene‐3,17‐dione into polar products and the formation of formaldehyde from aminopyrine were about 4 and 2.6 times higher, respectively, in phenobarbital‐treated rats than in control rats. The results indicate that the 7α‐hydroxylase catalyzing the conversion of cholesterol into cholest‐5‐ene‐3β,7α‐diol and the 12α‐hydroxylase catalyzing the conversion of 7α‐hydroxycholest‐4‐en‐3‐one into 7α,12α‐dihydroxycholest‐4‐en‐3‐one are different from the drug‐metabolizing enzyme systems.
Bovine Pancreatic Ribonuclease‐Spectrophotometric Investigations of the Interaction of the Enzyme with Nucleotides
Authors: Deavin A. , Fisher R. , Kemp C. M. , Mathias A. P. , Rabin B. R.
Published: March 2005

Spectral changes on interaction of ribonuclease with a number of nucleotides have been measured. For guanine nucleotides these changes are the same as those produced by protonation of the guanine chromophore. It is concluded that the guanine ring of nucleotides interacts with an acid group of the protein in position N‐7. Evidence is presented for a similar interaction of the enzyme with the purine ring of adenine nucleotides. For uridine nucleotides the spectral changes on interaction with the enzyme are the same as those produced by de‐protonation of the pyrimidine ring in a partially hydrophobic environment. It is concluded that the pyrimidine ring of nucleotides interacts with a base group of the protein. The triphosphates of uridine, cytidine, guanine and adenine all form 1:1 ligand: enzyme complexes.
Beef Pancreas Tryptophanyl‐tRNA Synthetase
Authors: Lemaire G. , Gros C. , Labouesse B. , VAN Rapenbusch R.
Published: March 2005

The molecular weight of beef pancreatic tryptophanyl‐tRNA synthetase has been determined by Sephadex filtration, by equilibrium sedimentation according to Yphantis and to Van Holde and Baldwin, and by light scattering. These different techniques indicate an average molecular weight of 108000. The amino acid composition has been determined after total acid hydrolysis of the performic acid oxidized and of the carboxymethylated reduced protein. Spectrophotometric measurements, according to Edelhoch, have been used for tryptophan determination. The cysteine and cystine content have been measured before and after reduction by sodium borohydride in urea. From this study it is concluded that tryptophanyl‐tRNA synthetase contains no disulfide bridge. Its molecular extinction coefficient at 280 nm is 9 × 104. The optical rotatory dispersion of the enzyme indicates that it contains about a third of its polypeptide chain in helical conformation.
Electrophoresis of Ribosomes in Agar Gel
Authors: Dessev G. N. , Venkov C. D. , Tsanev R. G.
Published: March 2005

Electrophoretic separation in agar gel has been achieved for ribosomes from rat liver and Escherichia coli and their subunits. These particles were characterized by their mobility. RNA was extracted from the agar gel zones containing the two subunits of rat liver. It was found that the faster subunit contained only 18 S RNA with a base composition identical with that of 18 S cytoplasmic rat liver RNA. The slow subunit contained 18 S and 28 S RNA, both having the base composition of 28 S cytoplasmic RNA. The technique also provides a means of studying the labelling pattern of the ribosomes, contaminants being quantitatively removed by washing of the gel with acid.
The Cross Striation Pattern of the Fibrin Fibril
Authors: Karges Hermann E. , Kühn Klaus
Published: March 2005

Two different cross striation patterns can be seen under the electron microscope when fibrin fibrils are treated with heavy metal salts. The first shows two bands of different intensities per period (Type I), while the second has four bands per period (Type II). In this work, the factors involved in the formation of this particular cross striation pattern have been investigated. The origin of the Type I pattern is attributed to a reaction between uranyl acetate or phosphotungstic acid with the polar groups of fibrin (positive staining). Type II pattern arises from the embedding of excess heavy metal salts in the loosely structured portions of the fibrin fibril (negative staining). The sites of accumulation of the polar groups are not the areas of greatest mass density of the molecule.
The Association of Brain Hexokinase with Mitochondrial Membranes and its Functional Implications
Authors: Vallejo Carmen G. , Marco Roberto , Sebastián Jesús
Published: March 2005

The intracellular location of brain hexokinase and the nature of its association with mitochondria were studied in calf and rat. Three different media were used in order to minimize possible artifacts in the homogenization process.

Subcellular fractionation was followed testing, in addition to hexokinase, certain enzymes known as markers for the different cellular fractions. In the conditions used, hexokinase was almost entirely associated with mitochondria in calf, but only partially associated in rat. This is at variance with the rest of the enzymes involved in the glucose 6‐phosphate crossroads. The use of a “physiological saline” homogenization medium resulted in a considerable increase in the proportion of soluble hexokinase in rat brain.

Repeated washings of mitochondria from calf brain released little hexokinase, but in rat brain a rapid release was observed.

Upon submitochondrial fractionation by Sottocasa's method, a substantial amount of hexokinase appeared bound to the inner membrane in the case of calf brain. In rat brain, the evidence found also points to the binding of the greater part of hexokinase to the inner membrane.

Brain mitochondria were found to be sensitive to atractyloside, which made it possible to locate mitochondrial bound hexokinase as external to the ATP barrier, both in calf and rat.

These results indicate that mitochondrially bound hexokinase is only active on substrates located in the cytosol.
The Effects of 2‐Ethylcitrate and Tricarballylate on Citrate Transport in Rat Liver Mitochondria and Fatty Acid Synthesis in Rat White Adipose Tissue
Authors: Robinson Brian H. , Williams G. Ronald , Halperin Mitchell L. , Leznoff Clifford C.
Published: March 2005

2‐Ethylcitrate and propane 1,2,3 tricarboxylic acid (tricarballylate) were found to be inhibitors of the citrate transporting system as monitored by cis‐aconitate and isocitrate oxidation. Kinetic data showed the inhibitions to be competitive with tricarboxylate anion. When the exchange of intramitochondrial [14C]citrate with added extramitochondrial citrate or l‐malate was measured at low temperatures, 2‐ethylcitrate and 2‐propylcitrate were found to be good inhibitors, while tricarballylate did not inhibit and in fact was found to be a good substrate for exchange on the transporting system. Neither 2‐ethylcitrate nor tricarballylate at low concentrations (<10 mM) were found to inhibit fatty acid synthesis with pyruvate as precursor in rat white adipose tissue but both were potent inhibitors of fatty acid synthesis with glucose as precursor. The implications of these findings are discussed.
Level of Methionyl‐tRNA Synthetase in Merodiploids of Escherichia coli K12
Authors: Cassio Doris , Lawrence Françoise , Lawrence David A.
Published: March 2005

The specific activity of aminoacyl‐tRNA synthetases has been determined in strains of Escherichia coli K12 carrying the F32 episome. These strains were presumed to be diploid for the structural gene of methionyl‐tRNA synthetase. Of eighteen different aminoacyl‐tRNA synthetases tested, all but one showed similar levels of activity in both the merodiploids and the haploid strain of reference Hfr H. The only exception was methionyl‐tRNA synthetase, the level of which was four‐fold higher than that of the haploid strain, regardless of growth conditions. Parental strains of one of the merodiploids were studied. The female parent had the same level of methionyl‐tRNA synthetase as the hapoid HfrH strain, whilst the male parent Hfr AB 311, from which the F32 episome originated, had three times the level of the haploid HfrH strain. In both parental strains the level of valyl‐tRNA synthetase was the same as in the HfrH strain.
Purification of Ornithine Carbamoyltransferase from Halobacterium salinarium
Authors: Dundas Ian E. D.
Published: March 2005

Ornithine carbamoyltransferase from Halobacterium salinarium is a typical extremely halophilic enzyme. It is rapidly and irreversibly inactivated when exposed to a salt‐free environment and shows high activity at NaCl concentrations above 4 M. The present paper describes the purification of the enzyme from cell free extracts, by acetone fractionation, gel filtration, sucrose gradient centrifugation and chromatography on calcium phosphate gels. All purification procedures were carried out on 4.3 M NaCl solutions to prevent irreversible inactivation of the enzyme. Ornithine (0.1 M) stabilizes the enzyme and was included throughout the purification. The purified enzyme was essentially homogeneous as judged by polyacrylamide gel electrophoresis and by analytical ultracentrifugation. Enzyme activity was measured as citrulline formation from ornithine and carbamoylphosphate in the presence of 4.3 M NaCl, at 37°. Specific activity of the purified enzyme was about 1 μmole citrulline formed per minute per μg protein or an about 50‐fold increase from that of cell‐free extracts. Halophilic enzymes which can not be reactivated from a salt‐free environment have not previously been extensively purified.
Interactions entre l'acide désoxyribonucléique et les histones
Authors: Touvet‐Poliakow Marie‐Claire , Daune Michel P. , Champagne Madeleine H.
Published: March 2005

Reconstitution in vitro of complexes between DNA and histone fractions (F1 and F3), each properly purified, is performed at high salt concentrations (∼ 1 M), followed by a progressive dialysis of the mixtures against decreasing ionic strengths.

In a first approach, we study at pH = 5.4, the formation of a coacervate inside these mixtures, using low speed centrifugation, and measuring DNA and histone concentrations in the supernatants, as a function of the ratio of histone/DNA (w/w) in the initial mixture, and the molarity of the salt (NaCl). Interactions between DNA and histones are essentially electrostatic. However, the total number of positive charges on the histone molecules cannot explain the greater efficiency of F1 to precipitate DNA compared with F3. Uneven distribution of positive charges along histone molecules are to be considered, together with hydrophobic interactions between histones.

Then by means of appropriate sucrose gradients, the existence of two complexes can be clearly demonstrated, the relative amount of each depending upon the ionic strength and the initial ratio histone/DNA in the mixture. The first complex, called “soluble”, is obtained alone only for very small values of histone/DNA ratio. With increasing amounts of histone, there appears a second complex called “aggregate”, which is in fact the first step in the formation of the coacervate.

Distinct physico‐chemical factors govern each step of the binding process and it must be pointed out that the first step (soluble complex) only can be used to characterize the affinity of histone to DNA.

The second step (coacervate) appears as an insoluble precipitate in the case of F1. In the case of F3, an intermediary state in the formation of the coacervate consists of stable aggregates, whose size and polydispersity are related to the initial F3/DNA ratio.

The former case is somewhat similar to the complexes of DNA with polylysine, but the latter one resembles the artificial complexes between lysozyme and DNA.

A tentative model is proposed for F3‐DNA aggregates where DNA is first folded into rodlike particles which in turn are organized into quasi‐spherical and highly hydrated micelles.
The Concurrent Regulation of Metabolically Related Enzymes
Authors: Flavell Richard B. , Woodward Dow O.
Published: March 2005

The kinetics of derepression of isocitrate lyase, malate synthase, phosphoenolpyruvate carboxykinase, citrate synthase, fumarate hydratase, and malate dehydrogenase were studied following transfer of mycelium grown on a medium containing sucrose to one containing acetate as sole source of carbon. The maximum rate of isocitrate lyase synthesis was proportional to the number of isocitrate lyase structural genes. Comparisons of the repressed levels of isocitrate lyase and malate synthase on sucrose medium and the derepressed levels in acetate medium showed an over‐all coordination between the levels of these two enzymes. A similar relationship existed between the levels of fumarate hydratase, citrate synthase and malate dehydrogenase. The Krebs cycle enzymes also showed coordinate repression on sucrose medium under conditions of enhanced catabolite repression. Other results, however, showed that neither for the glyoxylate shunt enzymes nor for the Krebs cycle enzymes was this coordination invariable. Under conditions in which some of the Krebs cycle enzymes assumed different roles no coordination was observed. It is suggested that this type of coordination, which is frequently observed in the pathways of central carbon metabolism in eucaryotes, results from the metabolic repressors of each enzyme being in equilibrium or in a constant ratio to one another. The coordination does not arise because the structural genes of each enzyme belong to the same operon.