Structure formation and hydrogen bonding in all-aliphatic segmented copolymers with uniform hard segments.

Fully aliphatic segmented poly(ether ester amide) copolymers with uniform hard segments prepared by melt polycondensation of α,ω-hydroxyl end-functionalized polytetrahydrofuran and short glycine or ß-alanine bisester-bisoxalamide units hold promise for biomedical applications. For polymers with the hard block contents varying from 10% to 27%, differential scanning calorimetry and atomic force microscopy reveal a highly phase-separated morphology, with ribbon-like nanocrystals dispersed in the soft segment matrix. To relate the polymer properties to the structure of the hard segment, the monomers were prepared and studied by optical and X-ray diffraction measurements. It was shown that the glycine and ß-alanine carbonyl ester groups are tilted away from the oxalamide plane, which can affect the degradation rate via hydrolysis of the ester bond.

Impact of co-morbid mental illness on the diagnosis and management of patients hospitalized for medical conditions in a general hospital.

AIMS: Comorbidities including hyperglycemia, diabetes, and hypertension are frequently observed in psychiatric patients. Nevertheless, this population has higher rates of morbidity and mortality from medical illnesses compared to non-psychiatric patients. The present study evaluated the diagnosis and management of general medical hospitalized patients with and without mental illness. METHODS: The study group consisted of 200 hospitalized subjects including 100 subjects who met the DSM-IV criteria for schizophrenia or bipolar disorder and 100 age-matched controls. All patients were evaluated for a comorbid condition, concomitant medication, biochemical parameters. Comorbid conditions were defined using the National Cholesterol Education Program risk factors categories: diabetes (fasting plasma glucose level > or = 126 mg/dl and/or pharmacological treatment); hypertension (systolic blood pressure > or =140 mm Hg and/or diastolic BP > or = 90 mm Hg and/or pharmacological treatment); dyslipidemia (hypertriglyceridemia (> or = 150 mg/dl); and/or pharmacological treatment and/or low HDL cholesterol level (< 40 mg/dl in men and < 50 mg/dl in women). RESULTS: The two groups were similar in terms of age, sex, mean blood pressure, glucose, and lipids. Patients with a history of psychiatric illness were less frequently diagnosed with medical conditions such as hypertension, dyslipidemia, and diabetes compared to the non-psychiatric population, though according NCEP criteria, these conditions did not significantly differ between the two groups. Significantly fewer psychiatric than non-psychiatric patients received aspirin, statins, anti-hypertensive and anti-diabetic medications. Although more obesity was diagnosed in psychiatric patients, significantly fewer diet consults were performed during hospitalization. While significantly more smokers and more pulmonary hospitalizations were observed in the psychiatric group, fewer subjects in this group received instruction for smoking cessation compared to the non-psychiatric population. CONCLUSIONS: Comorbid medical conditions such as diabetes, hypertension, dyslipidemia, and obesity are under-diagnosed and under-treated in hospitalized psychiatric patients compared with the non-psychiatric population. Patients with mental illness have significantly less preventive intervention during hospitalization.

The role of Bordetella infections in patients with acute exacerbation of chronic bronchitis.

BACKGROUND: Acute exacerbations of chronic bronchitis (AECB) are associated with a variety of viral and bacterial infectious agents, some of which are potentially preventable by immunization. Bordetella pertussis, which causes whooping cough, has not been studied in this context. We aimed to assess the role of Bordetella infections in patients with AECB. PATIENTS AND METHODS: Patients with AECB, who presented to participating private practices in Basel, Switzerland, between October 2000 and June 2002, were evaluated by a standardized questionnaire, nasopharyngeal swabs for culture (Bordetella spp.), and PCR (Bordetella spp. and selected other respiratory pathogens) and paired blood samples for serologic diagnosis of Bordetella infection. RESULTS: A total of 26 patients (34-86 years of age) were recruited. All culture and PCR samples were negative. Serology revealed Bordetella infection in eight (31%) patients. Duration of cough was shorter in patients with Bordetella infection compared to those without Bordetella infection (mean 15 days vs 41 days, p = 0.04). Cough > or = 21 days duration was present in three (43%) of seven patients with evidence of Bordetella infection compared to 17 (94%) of 18 controls (p = 0.012). Progression to convalescence from initial to follow-up visit after 4-6 weeks was comparable between both groups. CONCLUSION: Bordetella infections appear to play a significant role in AECB and preventive measurements such as immunization with acellular pertussis vaccines should be considered. Extended investigations are necessary to confirm our preliminary and provocative findings.

[Unusual gram positive rods, causing pneumonia]. / Ungewöhnliche grampositive Stäbchenbakterien als Auslöser von Pneumonien.

In the last decade, a growing number of patients with pneumonia, caused by unusual gram positive rods have been observed. Mostly, the patients had been infected as a consequence of impaired immunity. In some cases, bioterrorist activities may also induce pneumonia by gram positive rods (B. anthracis). In order to bring these organisms to the attention of the medical community, we present three clinical cases and describe six species of gram positive rods, known to provoke this kind of pneumonias. Case 1 was a 84 years old patient with impaired lung function. He was suspicious of tuberculosis (Tbc). Nocardia spec. was isolated. Case 2 was an alcoholic of 46 years with pneumonia. Reactivation of Tbc was suspected. Actinomadura madurae has been isolated. Case 3 was a patient of 58 years with myelodysplastic syndrome (MDS) and pneumonia. N. asteroides was isolated. All patients shared impaired immunity (age, alcoholism, MDS) with impaired lung functions; Tbc had been suspected (Case 1 + 2). Infection by A. madurae was contained by Clindamycin. Therapy of Nocardia with Moxifloxacin (Case 1) or Bactrim (Case 3) was only partly effective. In the appendix, six species of gram positive rods which are known to cause pneumonia, are summarized (Nocardia, Actinomyceta, Actinomadura, Rhodococcus, Corynebacterium and Bacillus).

Contamination of bronchoscopes with Mycobacterium tuberculosis and successful sterilization by low-temperature hydrogen peroxide plasma sterilization.

BACKGROUND: The transmission of mycobacteria by bronchoscopes has been reported several times in the last years. To explore methods to prevent transmission of tuberculosis in this way, we sterilized contaminated bronchoscopes with low-temperature hydrogen peroxide gas plasma sterilization. METHODS: Bronchoscopes were contaminated with Mycobacterium tuberculosis and decontaminated with a washer/disinfector ("normal washing"). Some were additionally disinfected with glutaraldehyde ("intensive washing"). Afterward the bronchoscopes were sterilized by low-temperature hydrogen peroxide plasma sterilization. RESULTS: After normal washing, 8/17 samples had positive results by culture, and 7/17 had positive results by nucleic acid amplification technique. After intensive washing, all samples had negative results by culture, and 10/25 had positive results by nucleic acid amplification technique; after sterilization with low-temperature hydrogen peroxide plasma sterilization, all samples had negative results by culture and nucleic acid amplification technique. CONCLUSION: Washing of bronchoscopes, as performed normally, is not sufficient for decontamination of bronchoscopes. Additional disinfection is recommended. If the nucleic acid amplification technique is used for diagnostic procedures, sterilization by low-temperature hydrogen peroxide plasma sterilization is recommended to avoid false-positive results.

Why multiple small subunits (Y2 and Y4) for yeast ribonucleotide reductase? Toward understanding the role of Y4.

Ribonucleotide reductases (RNRs) catalyze the conversion of nucleotides to deoxynucleotides. Class I RNRs are composed of two homodimeric subunits: R1 and R2. R1 is directly involved in the reduction, and R2 contains the diferric-tyrosyl radical (Y*) cofactor essential for the initiation of reduction. Saccharomyces cerevisiae has two RNRs; Y1 and Y3 correspond to R1, whereas Y2 and Y4 correspond to R2. Y4 is essential for diferric-Y* formation in Y2 from apoY2, Fe(2+), and O(2). The actual function of Y4 is controversial. Y2 and Y4 have been further characterized in an effort to understand their respective roles in nucleotide reduction. (His)(6)-Y2, Y4, and (His)(6)-Y4 are homodimers, isolated largely in apo form. Their CD spectra reveal that they are predominantly helical. The concentrations of Y2 and Y4 in vivo are 0.5-2.3 microM, as determined by Western analysis. Incubation of Y2 and Y4 under physiological conditions generates apo Y2Y4 heterodimer, which can form a diferric-Y small middle dot when incubated with Fe(2+) and O(2). Holo Y2Y4 heterodimer contains 0.6-0.8 Y* and has a specific activity of 0.8-1.3 micromol.min.mg. Titration of Y2 with Y4 in the presence of Fe(2+) and O(2) gives maximal activity with one equivalent of Y4 per Y2. Models for the function of Y4 based on these data and the accompanying structure will be discussed.

High-frequency (140-GHz) time domain EPR and ENDOR spectroscopy: the tyrosyl radical-diiron cofactor in ribonucleotide reductase from yeast.

High-frequency pulsed EPR and ENDOR have been employed to characterize the tyrosyl radical (Y*)-diiron cofactor in the Y2-containing R2 subunit of ribonucleotide reductase (RNR) from yeast. The present work represents the first use of 140-GHz time domain EPR and ENDOR to examine this system and demonstrates the capabilities of the method to elucidate the electronic structure and the chemical environment of protein radicals. Low-temperature spin-echo-detected EPR spectra of yeast Y* reveal an EPR line shape typical of a tyrosyl radical; however, when compared with the EPR spectra of Y* from E. coli RNR, a substantial upfield shift of the g(1)-value is observed. The origin of the shift in g(1) was investigated by 140-GHz (1)H and (2)H pulsed ENDOR experiments of the Y2-containing subunit in protonated and D(2)O-exchanged buffer. (2)H ENDOR spectra and simulations provide unambiguous evidence for one strongly coupled (2)H arising from a bond between the radical and an exchangeable proton of an adjacent residue or a water molecule. Orientation-selective 140-GHz ENDOR spectra indicate the direction of the hydrogen bond with respect to the molecular symmetry axes and the bond length (1.81 A). Finally, we have performed saturation recovery experiments and observed enhanced spin lattice relaxation rates of the Y* above 10 K. At temperatures higher than 20 K, the relaxation rates are isotropic across the EPR line, a phenomenon that we attribute to isotropic exchange interaction between Y* and the first excited paramagnetic state of the diiron cluster adjacent to it. From the activation energy of the rates, we determine the exchange interaction between the two irons of the cluster, J(exc) = -85 cm(-)(1). The relaxation mechanism and the presence of the hydrogen bond are discussed in terms of the differences in the structure of the Y*-diiron cofactor in yeast Y2 and other class I R2s.

Two-dimensional ENDOR-ESEEM correlation spectroscopy

A two-dimensional (2D) experiment that correlates electron-nuclear double resonance (ENDOR) and electron spin-echo envelope modulation (ESEEM) frequencies, useful for unraveling and assigning ENDOR and ESEEM spectra from different paramagnetic centers with overlapping EPR spectra, is presented. The pulse sequence employed is similar to the Davies ENDOR experiment with the exception that the two-pulse echo detection is replaced by a stimulated echo detection in order to enhance the resolution in the ESEEM dimension. The two-dimensional data set is acquired by measuring the ENDOR spectrum as a function of the time interval T between the last two microwave pulses of the stimulated echo detection scheme. This produces a series of ENDOR spectra with amplitudes that are modulated with T. Fourier transformation (FT) with respect to T then generates a 2D spectrum with cross peaks connecting spectral lines of the ESEEM and ENDOR spectra that belong to the same paramagnetic center. Projections along the vertical and horizontal axes give the three-pulse FT-ESEEM and ENDOR spectra, respectively. The feasibility of the experiment was tested by simulating 2D ENDOR-ESEEM correlation spectra of a system consisting of an electron spin (S = (1/2)) coupled to two nuclei (I(1) = I(2) = (1/2)), taking into account experimental conditions such as pulse durations and off-resonance irradiation frequencies. The experiment is demonstrated on a single crystal of Cu(2+) doped l-histidine (Cu-His), containing two symmetrically related Cu(2+) sites that at an arbitrary orientation exhibit overlapping ESEEM and ENDOR spectra. While the ESEEM spectrum is relatively simple and arises primarily from one weakly coupled (14)N, the ENDOR spectrum is very crowded due to contributions from two nonequivalent nitrogens, two chlorides, and a relatively large number of protons. The simple ESEEM projection of the 2D ENDOR-ESEEM correlation spectrum is then used to disentangle the ENDOR spectrum and resolve two sets of lines corresponding to the different sites. Copyright 2000 Academic Press.

High-field EPR detection of a disulfide radical anion in the reduction of cytidine 5'-diphosphate by the E441Q R1 mutant of Escherichia coli ribonucleotide reductase.

Class I ribonucleotide reductases (RNRs) are composed of two subunits, R1 and R2. The R2 subunit contains the essential diferric cluster-tyrosyl radical (Y.) cofactor and R1 is the site of the conversion of nucleoside diphosphates to 2'-deoxynucleoside diphosphates. A mutant in the R1 subunit of Escherichia coli RNR, E441Q, was generated in an effort to define the function of E441 in the nucleotide-reduction process. Cytidine 5'-diphosphate was incubated with E441Q RNR, and the reaction was monitored by using stopped-flow UV-vis spectroscopy and high-frequency (140 GHz) time-domain EPR spectroscopy. These studies revealed loss of the Y. and formation of a disulfide radical anion and present experimental mechanistic insight into the reductive half-reaction catalyzed by RNR. These results support the proposal that the protonated E441 is required for reduction of a 3'-ketodeoxynucleotide by a disulfide radical anion. On the minute time scale, a second radical species was also detected by high-frequency EPR. Its g values suggest that this species may be a 4'-ketyl radical and is not on the normal reduction pathway. These experiments demonstrate that high-field time-domain EPR spectroscopy is a powerful new tool for deconvolution of a mixture of radical species.

Combined ultramicrotomy for AFM and TEM using a novel sample holder.

A new sample holder that allows combined microtomy for atomic force microscopy (AFM) and transmission electron microscopy (TEM) is described. The main feature of this sample holder is a small central part holding the sample. This central part fits into the head of an atomic force microscope. AFM measurements can be performed with a sample mounted in this central part of the sample holder. This makes the alignment of a microtomed bulk sample unnecessary, and offers the opportunity of an easy and fast combined sample preparation for AFM and TEM.

Mycobacterium ulcerans infection in a child from Angola: diagnosis by direct detection and culture.

Buruli ulcer, caused by Mycobacterium ulcerans, is a chronic ulcerative skin disease, found predominantly in central and west Africa and Australia. A boy of 2.5 years of age from Angola was admitted to our hospital with severe kwashiokor and a large ulcer with undermined edges on the left side of the thorax. Further examination revealed anaemia, hypoproteinaemia, bacterial superinfection of the ulcer and intestinal parasites. Histological analysis showed acid-fast bacilli and histopathological changes typical of Buruli ulcer. M. ulcerans was detected by PCR and culture. The patient was treated by surgical excision of diseased skin, followed by split-skin grafting. He also received antibiotic therapy (ciprofloxacin, clarithromycin, rifabutin, and dapsone). After six months, the child was discharged from hospital in good condition. This is the first published case of Buruli ulcer from Angola.

Albinism in Malawi

The rehabilitation programme showed that many teenage albino patients; after visiting eye and skin clinics; started to gain in self-confidence at school. It is hoped that as a result of this programme albino patients will seek medical help more readily in the future than they do now

Purification and properties of arogenate dehydrogenase from Actinoplanes missouriensis.

Actinoplanes missouriensis utilizes arogenate as an intermediate in L-tyrosine biosynthesis, while no evidence of prephenate dehydrogenase was observed. Arogenate dehydrogenase has been partially purified by a five-step procedure. The enzyme requires NAD as cofactor. The Km values for NAD and arogenate are 0.2 mM and 0.15 mM, respectively. The molecular weight of arogenate dehydrogenase is about 68,000, and SDS gel electrophoresis indicates a composition of two identical subunits. The enzyme is not feedback inhibited by L-tyrosine and unaffected by L-phenylalanine, prephenate, phenylpyruvate, p-hydroxyphenylpyruvate or L-tryptophan. Arogenate dehydrogenase is quite sensitive to p-hydroxymercuribenzoate with 50% inhibition at 12.5 microM of the SH-specific reagent. The presence of malate in usually applied arogenate preparations is demonstrated and the consequence of an impure substrate on arogenate dehydrogenase studies is discussed.

[Experiences with the self-supporting type SCL hip screw prosthesis]. / Erfahrungen mit der selbsthaltenden Hüftschraubprothese vom Typ SCL.

After having experienced different systems of cementless bonding for 12 years the method of screwing--in prostheses has been applied for several years now. In doing so a cementless fixing-system has been created while the implants--acetabulum cup and femoral infibulum--contact the bone with the whole surface and they are primarily fixbonded to the bone. The result of the fellow-up examinations are very satisfactory and positive results are expected as well for future fellow up examinations.