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2.
Internist (Berl) ; 58(11): 1171-1182, 2017 Nov.
Article in German | MEDLINE | ID: mdl-29027568

ABSTRACT

Acromegaly is a rare and severe condition, presenting with typical signs and symptoms. The diagnosis is often initially made years after the first manifestations of the disease. In more than 99% of patients the disease is caused by a benign pituitary tumor that secretes growth hormone (GH). The diagnosis is based on the presence of increased insulin-like growth factor 1 (IGF-1) levels and a lack of GH suppression in the oral glucose tolerance test. The standard imaging procedure for tumor detection is magnetic resonance imaging in the region of the sella turcica. Treatment includes surgical, drug and radiation therapy. Important factors are an intensive aftercare of the patient, controls for detection of tumor recurrence and pituitary insufficiency as well as assessment of various organ functions and risk constellations. Patient care should involve close cooperation between endocrinologists, neurosurgeons and general practitioners as well as other specialist disciplines.


Subject(s)
Acromegaly/diagnosis , Acromegaly/blood , Acromegaly/therapy , Adenoma/diagnosis , Adenoma/therapy , Comorbidity , Diagnosis, Differential , Growth Hormone-Secreting Pituitary Adenoma/diagnosis , Growth Hormone-Secreting Pituitary Adenoma/therapy , Humans , Insulin-Like Growth Factor I/analysis , Interdisciplinary Communication , Intersectoral Collaboration , Rare Diseases
3.
Scand J Immunol ; 85(3): 191-196, 2017 Mar.
Article in English | MEDLINE | ID: mdl-28128856

ABSTRACT

The pathogenesis of rheumatoid arthritis (RA) is incompletely understood. Human endogenous retroviruses (HERVs) and their superantigenic envelope protein (env) have been implicated in the pathogenesis of RA. In the present investigation, the arthritogenic potential of the superantigen staphylococcal enterotoxin A (SEA) has been investigated. In the present investigation, the bacterial superantigen staphylococcal enterotoxin A (SEA) was injected into the right knee joint of 15 Lewis rats. Further nine animals received saline. Animals were sacrificed one, five and 10 days after the injection, respectively. The antigens CD3, CD4, CD8, MHC class I, MHC class II, Pax5 and CD138 were investigated by immunohistochemistry on cryo-sections. After intra-articular SEA injection, the inflammation was initially dominated by CD8+ T cells. In the course of the investigation, the numbers of CD4+, Pax5+, CD138+ and MHC class II+ cells increased. CD3 was expressed in low numbers as compared to CD8. After saline injection, no similar inflammatory response has been detected. The arthritis induced by the superantigen SEA may be a novel model for inflammatory joint diseases, that is rheumatoid arthritis or juvenile idiopathic arthritis.


Subject(s)
Arthritis, Experimental/immunology , Arthritis, Experimental/pathology , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Enterotoxins/immunology , Superantigens/immunology , Animals , Arthritis, Rheumatoid/pathology , B-Lymphocytes/immunology , CD3 Complex/metabolism , CD4 Antigens/metabolism , CD8 Antigens/metabolism , Disease Models, Animal , Histocompatibility Antigens Class I/metabolism , Histocompatibility Antigens Class II/metabolism , Male , PAX5 Transcription Factor/metabolism , Rats , Rats, Inbred Lew , Syndecan-1/metabolism
4.
Neurogastroenterol Motil ; 27(8): 1082-8, 2015 Aug.
Article in English | MEDLINE | ID: mdl-26009871

ABSTRACT

BACKGROUND: The influence of physical strain on the esophageal motility has already been examined in a number of studies. It was found that high physical strain compromises the sufficient contractility of the esophagus. However, it needs more examinations to verify these findings. METHODS: To validate these results healthy volunteers were examined using gas-perfusion manometrie. Bicycle ergometry was performed to generate an exactly defined physical exercise. After a pilot study, the changing of the contraction amplitude was determined as the main variable to evaluate the esophageal motility, and the sample size was calculated. Eight subjects without esophageal diseases or symptoms were examined by simultaneous gas-perfusion esophageal manometry and bicycle ergometry. KEY RESULTS: The results showed that high physical strain during bicycle ergometry can induce a significant decrease of the contraction amplitude (α = 5%, ß = 10%). The 95% confidence interval of the quotient of contraction amplitude at rest and under physical strain is (1.074; 1.576). This effect is more pronounced in liquid acts of swallowing than in dry and is also more obvious at the middle measuring point (7.8 cm above the lower esophageal sphincter) than at the distal and proximal point (2.8 and 12.8 cm). Furthermore, a decreasing tendency of the contraction duration could be found. CONCLUSIONS & INTERFERENCES: Gas-perfusion manometry is an inexpensive examination method, which enables the evaluation of the esophageal motility in moving test subjects under conditions of physical strain. It could be proved that physical strain negatively influences the esophageal motility by a decrease of the contraction amplitude.


Subject(s)
Esophagus/physiology , Gastrointestinal Motility , Physical Exertion , Adult , Esophageal Sphincter, Lower/physiology , Exercise , Exercise Test , Female , Healthy Volunteers , Humans , Male , Manometry , Muscle Contraction
5.
Z Gastroenterol ; 52(4): 343-7, 2014 Apr.
Article in German | MEDLINE | ID: mdl-24718938

ABSTRACT

Gastro-oesophageal reflux (GER) has a special meaning for patients with cystic fibrosis (CF). Twelve voluntary patients with CF up to the age of 25 underwent an oesophageal manometry and a 24-hour impedance-pH monitoring. These patients were without symptoms of GER. The examination proved an acid GER in 42 %. In the total population the frequency is ≤ 10 %. In 11 of 12 patients a pathologically low pressure of the lower oesophageal sphincter (LES) was found. No significant correlations between the DeMeester score and the pressure of the LES, the reflux and respiratory symptomatology, the lung function as well as the quality of life could be proven. However, there was a significant correlation between the DeMeester score and the acid clearance time. 37 % of the registered cough pushes were related to a GER, of which 78 % were associated with an acid GER. Therefore, coughing in patients with CF must not necessarily be caused by the underlying disease. The timely detection of a pathological GER in patients with CF, but without symptoms of GER, and its prompt therapy could protect the lung function.


Subject(s)
Cystic Fibrosis/diagnosis , Cystic Fibrosis/physiopathology , Esophagogastric Junction/physiopathology , Esophagus/chemistry , Esophagus/physiopathology , Gastroesophageal Reflux/diagnosis , Gastroesophageal Reflux/physiopathology , Adult , Cystic Fibrosis/complications , Esophageal pH Monitoring , Female , Gastric Acidity Determination , Gastroesophageal Reflux/etiology , Humans , Hydrogen-Ion Concentration , Male , Manometry , Reproducibility of Results , Sensitivity and Specificity
6.
Med Klin Intensivmed Notfmed ; 107(7): 558-63, 2012 Oct.
Article in English | MEDLINE | ID: mdl-22875037

ABSTRACT

BACKGROUND: Severe infections play an important role in the emergency department (ED) and early risk stratification is essential. We compared the prognostic value of APACHE II, SOFA, and MEDS scores, and the biomarkers C-reactive protein (CRP), procalcitonin (PCT), and interleukin 6 (IL-6). METHODS: We performed a prospective observational study. Patients aged 18 years or older with a severe infection, from whom blood cultures were taken, were included. RESULTS: Two hundred and eleven patients were included. The 30-day mortality rate was 8.5%. All scores and biomarkers showed significant area under the curve (AUC) values of receiver operating characteristic curve analysis for death within 30 days: 0.801 for APACHE II, 0.785 for MEDS, 0.708 for SOFA, 0.693 for CRP, 0.651 for PCT, and 0.716 for IL-6. For treatment in an ICU and need for mechanical ventilation, these parameters had significant AUC values, too. For renal replacement therapy, only APACHE II, SOFA, and PCT showed significant AUC values. According to the trend observed, the AUC values were highest for the APACHE II score. CONCLUSIONS: All investigated parameters have a predictive value in patients with an infection in the ED. According to the trend observed, the APACHE II score seems to have the best discriminative power. Use of the APACHE II score already at the time of admission to the ED may be useful for stratifying patients at risk for ICU treatment, thereby using the same score in the ED and the ICU.


Subject(s)
Biomarkers/blood , Emergency Service, Hospital , Health Status Indicators , Sepsis/diagnosis , Sepsis/mortality , Adult , Aged , Aged, 80 and over , Comorbidity , Female , Humans , Intensive Care Units , Male , Middle Aged , Organ Dysfunction Scores , Predictive Value of Tests , Prognosis , Risk Assessment , Sepsis/classification , Severity of Illness Index
7.
Clin Radiol ; 64(7): 734-7, 2009 Jul.
Article in English | MEDLINE | ID: mdl-19520218

ABSTRACT

Ectopic pancreas is a rare congenital anomaly. It is usually asymptomatic, or presents with non specific gastrointestinal symptoms. We describe here a case of ectopic pancreas in the gastric antrum, with pseudocyst and pseudoaneurysm formation. This entity has not been reported previously in the literature.


Subject(s)
Aneurysm, False/diagnostic imaging , Choristoma/diagnostic imaging , Pancreas , Pancreatic Pseudocyst/diagnostic imaging , Stomach Diseases/diagnostic imaging , Diagnosis, Differential , Female , Humans , Infant, Newborn , Pyloric Antrum/diagnostic imaging , Tomography, X-Ray Computed/methods , Ultrasonography, Doppler, Color/methods
8.
Dtsch Med Wochenschr ; 129(19): 1059-64, 2004 May 07.
Article in German | MEDLINE | ID: mdl-15136950

ABSTRACT

BACKGROUND AND OBJECTIVE: Polycystic ovary syndrome (PCOS), with an incidence of 5% in women of reproductive age, is defined as the presence of oligo- or amenorrhea in combination with hyperandrogenism. Most patients also suffer from impaired insulin action (insulin resistance). PCOS thus resembles the metabolic syndrome (type 2 diabetes mellitus, hypertension, lipid disorders, atherosclerosis). International studies showed a beneficial effect of metformin treatment on biochemical and reproductive parameters in PCOS. The aim of our study is the evaluation of metformin treatment in a German PCOS sample. PATIENTS AND METHODS: 103 PCOS women (age 18-40) were treated, according to their body weight, with either 1000 mg or 1700 mg metformin per day after assessment of insulin resistance. Clinical features as well as endocrine and metabolic parameters were recorded at baseline and at 1, 6, and 12 months of treatment. Additionally, baseline data were compared with those of 98 control subjects (age 18-38). RESULTS: PCOS women showed significantly higher body mass index, body fat mass and androgen levels, as well as an impaired glucose- and insulin metabolism compared to controls. Metformin treatment ameliorated acne (36% to 4%), hirsutism-score (11.2 to 9.7) and restarted normal menstrual cycles in 66.7% of PCOS-women. Sixteen of 48 patients with unfulfilled wish to conceive became pregnant during therapy. Metformin restored menses in all previously amenorrheic women. Comparing post-metformin versus baseline levels, HOMA-IR (4.6 to 2.3), AUC-I (379 to 225) and 2-h glucose (117 to 90 mg/dl) decreased significantly. Furthermore, metformin decreased testosterone (2.9 to 1.8 nmol/l), free androgen index (9.1 to 5.3) and dehydroepiandrosterone levels (5.1 to 3.9 mg/l). CONCLUSION: Metformin improves significantly hyperandrogenism and insulin resistance in PCOS patients and appears to be an efficacious mode of therapy.


Subject(s)
Hypoglycemic Agents/therapeutic use , Metformin/therapeutic use , Polycystic Ovary Syndrome/drug therapy , Adolescent , Adult , Body Mass Index , Data Interpretation, Statistical , Female , Follow-Up Studies , Glucose Tolerance Test , Humans , Hypoglycemic Agents/administration & dosage , Insulin Resistance , Metformin/administration & dosage , Polycystic Ovary Syndrome/diagnosis , Prospective Studies , Time Factors
9.
J Clin Oncol ; 21(16): 3072-8, 2003 Aug 15.
Article in English | MEDLINE | ID: mdl-12915596

ABSTRACT

PURPOSE: Risk stratification of metastatic and relapsed Ewing's tumors (ETs) has been a matter of debate during the last decade. Patients with bone or bone marrow metastases or early or multiple relapses constitute the worst risk group in ET and have a poorer prognosis than patients with primary lung metastases or late relapses. In this article, the results of the present Meta European Intergroup Cooperative Ewing Sarcoma Study (MetaEICESS) (tandem melphalan/etoposide [TandemME]) were compared with the result of the previous study (hyper melphalan/etoposide [HyperME]), both at 5 years, in a patient population within the same high-risk stratum to determine toxicity. PATIENTS AND METHODS: Among 54 eligible patients, 26 were treated according to the HyperME protocol, and 28 were treated according to TandemME protocol. Patients received six cycles of the Cooperative Ewing Sarcoma Study treatment in HyperME and six cycles of the EICESS treatment in TandemME as induction chemotherapy. Patients also received involved-compartment irradiation for local intensification and myeloablative systemic intensification consolidation with hyperfractionated total-body irradiation (TBI) combined with melphalan/etoposide in HyperME or two times the melphalan/etoposide in TandemME followed by autologous stem-cell transplantation. RESULTS: The event-free survival (EFS) rate +/- SD in HyperME and TandemME was 22% +/- 8% and 29% +/- 9%, respectively. The dead of complication rate was 23% in HyperME and 4% in TandemME. CONCLUSION: TandemME offers a decent, albeit still not satisfactory, rate of long-term remissions in most advanced ETs (AETs), with short-term treatment and acceptable toxicity. TBI was not required to maintain EFS level in this setting but was associated with a high rate of toxic death. Future prospective studies in unselected patients are warranted to evaluate high-dose therapy in an unselected group of patients with AET.


Subject(s)
Sarcoma, Ewing/drug therapy , Whole-Body Irradiation , Adolescent , Adult , Antineoplastic Combined Chemotherapy Protocols , Bone Marrow Neoplasms/secondary , Bone Neoplasms/secondary , Child , Child, Preschool , Combined Modality Therapy , Disease-Free Survival , Etoposide/administration & dosage , Female , Humans , Male , Melphalan/administration & dosage , Middle Aged , Neoplasm Recurrence, Local , Sarcoma, Ewing/radiotherapy , Survival Analysis , Whole-Body Irradiation/adverse effects
11.
Inorg Chem ; 40(12): 2686-92, 2001 Jun 04.
Article in English | MEDLINE | ID: mdl-11375680

ABSTRACT

Glutathionylcobalamin (gamma-glutamylcysteinylglycinylcobalamin; gamma-GluCysGly-Cbl) is a natural product which functions as an intermediate in the biosynthesis of the active B(12) coenzymes adenosylcobalamin and methylcobalamin. Of interest to the present studies is glutathionylcobalamin's unique stability in comparison to other thiolatocobalamins, notably the > or =6 x 10(4) fold less stable cysteinylcobalamin, Cys-Cbl. In order to determine which parts of the glutathione tripeptide contribute to the overall stability of glutathionylcobalamin, two cysteine-containing dipeptides, which are truncated versions of glutathione, were used to synthesize their corresponding cobalamins, specifically gamma-glutamylcysteinylCbl (gamma-GluCys-Cbl) and cysteinylglycinylcobalamin (CysGly-Cbl). As with glutathionylCbl, the dipeptide gamma-GluCys-Cbl forms a stable thiolatocobalamin. However and most interestingly, CysGly-Cbl is observed to be unstable much like Cys-Cbl. The results require that the extra stability of glutathionylcobalamin and its congeners, compared to cysteinylcobalamin and its analogues, must be derived from destabilization by the gamma-NH(3)(+) group in cysteinylcobalamin, or stabilization by the gamma-NHC(=O)- amide linkage in glutathionylcobalamin, or both. To probe any ground-state structural basis for the possible stabilization in gamma-GluCys-containing cobalamins, gamma-GluCys-Cbl was crystallized and yielded the first X-ray structural determination of a true thiolatocobalamin, and only the second structure of a cobalamin containing a Co-S bond, the first example being Randaccio and co-workers' 1999 structure of the thioketone complex, thioureacobalamin, (NH(2))(2)CSCbl. Key features of the structure of gamma-glutamylcysteinylcobalamin include (i) a normal Co-S bond length of 2.267(2) A, (ii) a Co-N(axial) bond length of 2.049(6) A, (iii) two alternate conformations of the gamma-glutamylcysteinyl moiety, and (iv) folding of the corrin ring upward by 24.2 degrees, the highest degree of folding yet observed for a cobalamin. These results do not show any strong stabilization (e.g., no shortened Co-S bond), although it is not clear for certain what the effect is (stabilizing or destabilizing) of the elongated Co-N(axial) bond; instead, the crystallographic results suggest that the metastable Cys-Cbl probably has a Co-S cleavage transition state that is stabilized (along with, possibly, any ground-state destabilization of the Co-S bond). Overall, the results strongly suggest that placing a positive charge on the gamma-NH(3)(+) stabilizes the Co-S bond cleavage transition state, thereby setting the stage for the needed full thermolysis product and kinetic studies-as a function of the axial-base on-off equilibrium-that will be required to understand in even greater detail the unique stability of glutathionyl- (gamma-glutamylcysteinylglycinyl-) and gamma-glutamylcysteinylcobalamins.


Subject(s)
Dipeptides/chemistry , Glutamine/chemistry , Glutathione/chemistry , Vitamin B 12/chemistry , Cobalt/chemistry , Crystallography, X-Ray , Dipeptides/chemical synthesis , Glutamine/analogs & derivatives , Glutamine/chemical synthesis , Glutathione/analogs & derivatives , Molecular Conformation , Solutions , Sulfur/chemistry , Vitamin B 12/analogs & derivatives
12.
Unfallchirurg ; 103(9): 754-60, 2000 Sep.
Article in German | MEDLINE | ID: mdl-11039296

ABSTRACT

So far, little is known about the acoustic phenomena of high-frequency sonography for the assessment of healing processes in thermal wounds. However, ex vivo investigations have shown clear age-dependent differences in the rate of sound propagation in thermal scars compared to healthy skin. In order to answer the question of whether measurable acoustic characteristics of burn or scald scars can be classified in a way which corresponds to the clinical severity of the injuries, age of scar or type of treatment, 92 thermal scars, with an average scar age of 3.1 years, in 55 children were investigated with regard to corium thickness and echogenicity. A control group of 25 non-injured children of similar age was studied for comparison. It was shown that measurable echogenicity differences can allow conclusions about clinical severity to be drawn. The comparison of different therapeutic strategies showed no therapeutic effect either for compression or for the application of silicone gel sheets. In contrast, a decrease in scar thickness and a loosening of scar structure could be seen after early application of a sterile, silicone-covered polyamide net bandage. The 20-MHz-Sonography is a suitable non-invasive procedure for the characterisation of burn scars.


Subject(s)
Burns/diagnostic imaging , Burns/therapy , Cicatrix/diagnostic imaging , Cicatrix/therapy , Age Factors , Bandages , Child , Humans , Nylons , Silicone Gels , Silicones , Time Factors , Ultrasonography
15.
J Inorg Biochem ; 78(2): 149-60, 2000 Jan 30.
Article in English | MEDLINE | ID: mdl-10766338

ABSTRACT

Aqueous solutions of adenosylcobalamin (AdoCbl) were thermolyzed with excess beta-mercaptoethanol under anaerobic conditions. The product studies reveal that approximately 90% Co-C bond homolysis occurs, to yield Co(II)cobalamin, 5'-deoxyadenosine, and the disulfide product from the combination of two HOCH2CH2S* radicals, 2,2'-dithiodiethanol; there is also approximately 10% Co-C bond heterolysis, yielding Co(III)cobalamin, adenine, and 2,3-dihydroxy-4-pentenal. The kinetic studies show there is a first-order dependence on AdoCbl and zero-order dependence on thiol under the higher [RSH] experimental conditions used, consistent with the rate-determining step at high [RSH] being the generation of Ado*. The kinetic results require that, in enzyme-free AdoCbl solution, adenosyl radical (Ado*) is formed as a discrete intermediate which then abstracts H* from the added thiol. The activation parameters for Co-C bond homolysis in the presence of thiol trap are the same within experimental error as the activation parameters for Co-C bond homolysis without trap, standard delta H(obs) = 29(2) kcal mol(-1) and standard delta S(obs) = -1(5) e.u. The results, in comparison to the rate of Co-C bond homolysis in ribonucleoside triphosphate reductase (RTPR), reveal that RTPR accelerates Co-C bond cleavage in AdoCbl by approximately 10(10+/-1). The recent literature evidence bearing on the exact mechanism of RTPR enzymic cleavage of the Co-C bond of AdoCbl is briefly discussed, notably the fact that this mechanism is presently controversial, but does involve at least coupled (and possibly concerted) Co-C cleavage, -S-H cleavage, and C-H (Ado-H) formation steps.


Subject(s)
Adenosine/metabolism , Hydrogen/metabolism , Lactobacillus/enzymology , Ribonucleotide Reductases/metabolism , Sulfhydryl Compounds/metabolism , Adenosine/chemistry , Catalysis , Free Radicals , Sulfhydryl Compounds/chemistry
16.
Eur J Endocrinol ; 141(6): 563-9, 1999 Dec.
Article in English | MEDLINE | ID: mdl-10601957

ABSTRACT

OBJECTIVE: TGPO autoantibodies (aAbs) that bind simultaneously to thyroglobulin (Tg) and thyroperoxidase (TPO) are present in the serum of patients with autoimmune thyroid diseases (AITD) and have been found to differ from monospecific Tg and TPO aAbs. To obtain further insights on the prevalence defined as the rate of occurrence and significance of TGPO aAbs in a large population, we carried out a collaborative study involving 15 European teams. METHODS: Serum samples from 3122 patients with various thyroid and non-thyroid diseases and normal subjects were assayed using a novel TGPO aAb detection kit. This test was designed so that TGPO aAbs are trapped between the Tg-coated solid phase and the soluble TPO labeled with a radioiodinated monoclonal antibody. RESULTS: Only three out of the 220 normal subjects (prevalence of 1.4%) were found to have positive TGPO aAb levels, which were mainly observed in the patients with AITD: the group of patients suffering from Hashimoto's thyroiditis had a TGPO aAb prevalence of 40.5% (n=437 patients), those with Graves' disease, a prevalence of 34.6% (n=645) and those with post-partum thyroiditis, 16.0% (n=243). Among the non-AITD patients with positive TGPO aAb levels, the TGPO aAb prevalence ranged from 20.7% among those with thyroid cancer (n=246) to 0% among those with toxic thyroid nodules (n=47). Among the patients with non-thyroid diseases, the TGPO aAb prevalence ranged from 9.8% in the case of Biermer's pernicious anemia (n=78) to 0% in that of premature ovarian failure (n=44). It is worth noting that the groups showing the highest TGPO aAb prevalence also contained the patients with the highest TGPO aAb titers. Statistical comparisons between the TGPO aAb prevalences in the various groups showed that TGPO aAb could be used as a parameter to distinguish between the groups of Hashimoto's and Graves' patients and between the women with post-partum thyroiditis and the post-partum women with only Tg and/or TPO aAb established during early pregnancy. Unexpectedly, the correlations between TGPO aAbs and Tg and TPO aAbs were found to depend mainly on the assay kit used. CONCLUSION: High TGPO aAb titers are consistently associated with AITD but the reverse was not found to be true. TGPO aAbs are a potentially useful tool, however, for establishing Hashimoto's diagnosis, and would be worth testing in this respect with a view to using them for routine AITD investigations.


Subject(s)
Autoantibodies/blood , Iodide Peroxidase/immunology , Thyroglobulin/immunology , Thyroid Diseases/immunology , Autoimmune Diseases/immunology , Female , Graves Disease/immunology , Humans , Pregnancy , Puerperal Disorders/immunology , Reagent Kits, Diagnostic , Thyroiditis, Autoimmune/immunology
17.
J Inorg Biochem ; 76(3-4): 197-209, 1999 Sep 30.
Article in English | MEDLINE | ID: mdl-10605837

ABSTRACT

The syntheses, isolation and characterization of cyclohexylthiolatocobalamin (C6H11SCbl), glutathionylcobalamin (GluSCbl), and cysteinylcobalamin (CysSCbl) are reported in 75, 55, and 65% yield, respectively. Characterization was achieved using elemental analyses, L-SIMS (liquid secondary ion mass spectrometry), UV-visible spectroscopy and, for the more stable C6H11SCbl and GluSCbl, our recently established 1H NMR method (which emphasizes the readily interpreted aromatic region of the cobalamin's 1H NMR spectrum). Preliminary evidence is presented for clean homolysis of the RS-Co bond in C6H11SCbl, GluSCbl, and CysSCbl to give RS. and .Co(II)Cbl radical pairs analogous to those that are intermediates in ribonucleoside triphosphate reductase (RTPR). A summary is provided which emphasizes the seven variables identified to date, underlying the successful syntheses and isolation of thiolatocobalamins, variables which make the one-step syntheses of RSCbls considerably more complex than they initially appear. Also briefly discussed are the analogous protein-S-Cbl complexes that are seen as side-products in RTPR, and the probability that such side-products are formed when HOCbl.HX is used as a possible 'active-site inhibitor' complex with B12-dependent enzymes.


Subject(s)
Cobamides/metabolism , Glutathione/analogs & derivatives , Ribonucleotide Reductases/metabolism , Vitamin B 12/analogs & derivatives , Vitamin B 12/chemical synthesis , Glutathione/chemical synthesis , Ligands , Methanol , Spectrophotometry , Water
18.
Prep Biochem Biotechnol ; 29(3): 273-309, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10431931

ABSTRACT

Ribonucleoside triphosphate reductase (RTPR, EC 1.17.4.2) from Lactobacillus leichmannii is a 5'-deoxyadenosylcobalamin-dependent (AdoCbl; Coenzyme B12) enzyme. RTPR is also a prototypical adenosylcobalamin-dependent ribonucleotide reductase, one that, as its name indicates, converts ribonucleoside triphosphates (NTP) to deoxyribonucleoside triphosphates (dNTP). Upon substrate binding to RTPR, AdoCbl's cobalt-carbon bond is cleaved to generate cob(II)alamin, 5'-deoxyadenosine, and the cysteine (C408) derived thiyl radical. Five key cysteines (Cys 119, 408, 419, 731, and 736), from among the ten total cysteines, are involved in RTPR's catalytic mechanism. A critical examination of the RTPR isolation and purification literature suggested that the purification protocol currently used results in RTPR which contains 2040% microheterogeneity, along with minor contamination by other proteins. In addition, no report of crystalline RTPR has ever appeared. The literature indicates that irreversible cysteine oxidation (e.g., to -SO2H or -SO3H) is one highly plausible reason for the microheterogeneity of RTPR. The literature also indicates that improvement in the level of enzyme purity is the most effective next step in coaxing enzymes to crystallize that have previously failed to do so. A shortened, improved purification of RTPR has been developed, one involving a shorter purification time, a lower pH, a higher concentration of the more effective reductant DTT (all designed to help protect the cysteines from oxidation), and a final step utilizing our recently reported, improved dGTP-based affinity chromatography resin. The resultant RTPR is approximately 20-30% higher in both specific activity and in its ability to undergo single turnovers, and is homogeneous by mass spectrometry and dynamic light scattering. Additionally, the revised purification procedure eliminates > 30 proteins present in 2-3% amounts along with damaged RTPR that does not bind properly (i.e. tightly) to the dGTP-affinity resin. Finally, dGTP-based affinity chromatography purified RTPR has yielded the first reported, albeit small, single crystals of RTPR.


Subject(s)
Chromatography, Affinity/methods , Cobamides/metabolism , Deoxyguanine Nucleotides/chemistry , Lactobacillus/enzymology , Ribonucleotide Reductases/isolation & purification , Allosteric Regulation/drug effects , Allosteric Site/drug effects , Chromatography, Agarose , Cobamides/chemistry , Crystallization , Crystallography , Electrophoresis, Polyacrylamide Gel , Escherichia coli/enzymology , Hydrogen-Ion Concentration , Mass Spectrometry , Models, Chemical , Resins, Synthetic/chemistry , Ribonucleotide Reductases/chemistry , Scattering, Radiation , Sodium Acetate/pharmacology , Substrate Specificity
19.
J Inorg Biochem ; 73(4): 215-9, 1999 Apr.
Article in English | MEDLINE | ID: mdl-10376344

ABSTRACT

A straightforward and simple, but powerful and direct, method is presented for both the detection and quantitation of cobalamin impurities in either commercial cobalamins or in metastable cobalamins (Cbls), such as RSCbls. The method is, quite simply, the use of the aromatic region of the 1H NMR of cobalamins; it is a method developed as an outgrowth of our work preparing metastable thiolatocobalamins (RSCbls) and is a method that proved necessary for characterizing those (and by inference other) cobalamins unstable to HPLC separation conditions (i.e., and, therefore, where the normally powerful HPLC method so commonly used in cobalamin chemistry fails). Despite considerable, prior, modern multidimensional NMR literature on cobalamins, the present method has not yet been indicated explicitly, nor has anyone reported previously the NMR data required to prove that the method works (i.e., the data for a series of cobalamins and their common impurities proving that they have different chemical shifts in the aromatic region of their 1H NMR when examined under identical NMR solvent, pH and other conditions). The direct NMR method is easy to perform, readily quantitated and applicable to species unstable to the HPLC conditions required to separate cobalamin impurities. The results have allowed quantitation of the 5-11% impurities in, for example, commercial HOCb1.HX, results which document that some commercially available cobalamins are not as pure as the manufacturers' claims.


Subject(s)
Vitamin B 12/chemistry , Chromatography, High Pressure Liquid , Drug Contamination , Magnetic Resonance Spectroscopy , Molecular Structure
20.
Nucleosides Nucleotides ; 17(8): 1453-71, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9672704

ABSTRACT

Seven nucleotides linked through the gamma-phosphate to diamine hydrocarbons were synthesized and coupled to Sepharose for use in protein purification affinity chromatography. The synthesis involved converting the nucleotides to nucleoside-5'- trimetaphosphates using dicyclohexyl carbodiimide, followed by nucleophilic ring opening of the trimetaphosphate with an alpha, omega-diamino hydrocarbon to generate a gamma-phosphoamide linkage in each nucleotide.


Subject(s)
Chromatography, Affinity/instrumentation , Proteins/isolation & purification , Resins, Plant/chemistry , Resins, Plant/chemical synthesis , Ribonucleotide Reductases/isolation & purification , Chromatography, Affinity/methods , Nucleosides , Phosphates
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