Caracemide, a site-specific irreversible inhibitor of protein R1 of Escherichia coli ribonucleotide reductase

The anticancer drug caracemide, N-acetyl-N,O- di(methylcarbamoyl)hydroxylamine, and one of its degradation products, N-acetyl-O-methylcarbamoyl-hydroxylamine, were found to inhibit the enzyme ribonucleotide reductase of Escherichia coli by specific interaction with its larger component protein R1. No effect on the smaller protein R2 was observed. The effect of the degradation product was about 30 times lower than that of caracemide itself. The caracemide inactivation of R1 is irreversible, with an apparent second-order rate constant of 150 M-1 s-1. The R1R2 holoenzyme was approximately 30 times more sensitive to caracemide inactivation than the isolated R1 protein. The ribonucleotide reductase substrates were potent competitors of the caracemide inhibition, with a Kdiss for GDP binding to R1 of 80 microM. The reducing agent dithiothreitol was also found to be a potent competitor of caracemide inactivation. These results indicate that caracemide inactivates R1 by covalent modification at the substrate-binding site. By analogy with the known interaction between caracemide and acetylcholinesterase or choline acetyltransferase, we propose that the modification of R1 occurs at an activated cysteine or serine residue in the active site of the enzyme.

Electron beam characteristics of the 50-MeV racetrack microtron

Electron beams in the MM50 racetrack microtron are generated by computer controlled scanning of a well-focused electron pencil beam. The treatment head is optimized to give a minimum of scatter between the source position and the collimator plane by a general minimization of all scattering material in the beam and by replacement of the air in the treatment head by helium, which has a much lower linear scattering power than air. A double-focused multileaf collimator with a 31-cm collimator to patient distance is used both for electron and photon collimation. In general, no extra electron collimation is needed for the standard SSD of 100 cm. To make irregular field collimation at a distance this far from the patient possible, a number of requirements have to be fulfilled regarding the virtual source position and the spatial and angular distribution of the initial electron beam. The virtual source position has been found to be at a fixed position for different irradiation parameters. This is important for the use of the light field in electron beam treatment but also for achieving a high degree of accuracy in the dosimetry. Scatter from the multileaf collimator has not been found to give any significant contribution to the radiation field or to the monitor output factor of the MM50. Experimental dose distribution data on the MM50 have been compared to data both from other types of treatment units and to Monte Carlo simulations.

Occupational and other environmental factors and multiple myeloma: a population based case-control study

Epidemiological studies on the aetiology of multiple myeloma are reviewed as a background to this population based case-control study performed in an area with a high incidence of multiple myeloma. The purpose was to identify and evaluate several suspected environmental factors in relation to this disease. A total of 275 confirmed cases diagnosed in four counties in northern Sweden during four years were compared with the same number of control subjects drawn from population registries. The controls were matched for age, sex, county, and vital status. Occupations and work associated exposures to chemicals and other potential carcinogens were assessed by an extensive questionnaire that also included questions on smoking habits, residential building materials, vicinity to electrical power lines, and leisure time contact with animals, electrical equipment, and chemicals. Information obtained from the questionnaires was completed by telephone interviews when necessary. Univariate analysis and multivariate logistic regression were performed. The study confirmed an association found earlier between farming and multiple myeloma. Some domestic animals (cattle, horses, and goats) and two types of pesticides (phenoxyacetic acids and DDT) were indicated as risk factors within farming. Exposure to electromagnetic fields, asbestos, and organic solvents were negatively associated with myeloma in this study.

Homologous collagen-induced arthritis in rats and mice are associated with structurally different major histocompatibility complex DQ-like molecules

Collagen-induced arthritis (CIA) in rats, induced with homologous type II collagen (CII), is a genetically more restricted disease and has better resemblance to rheumatoid arthritis by its chronic disease course, than CIA induced with heterologous CII. The DA strain is highly susceptible to CIA induced with homologous CII, while the Lewis strain is resistant. (DAxLew)F1 is susceptible and backcrossing to Lewis reveals a close, but not complete, association of both arthritis and CII responsiveness to the RT1a haplotype. Analyses of congenic strains on DA and Lewis backgrounds suggest that expression of a major histocompatibility complex class II Ba molecule, encoded from the RT1Ba locus, is associated with arthritis susceptibility and CII responsiveness. The second exons coding for the first domains of the alpha and beta chains of both the RT1a and RT1l haplotypes were sequenced and the deduced amino acid sequences compared with the corresponding molecule associated with susceptibility to CIA in the mouse (H-2 Aq). The sequences of the respective alleles revealed no obvious structural homology explaining the extensive similarities in the development of chronic autoimmune arthritis. Instead, this finding implies that different trimolecular constituents (i.e. class II, T cell receptor, and CII peptides) may yield an antigen presentation event that is able to trigger a similar autoaggressiveness in the two rodent species.

Dynamics of self-focusing and self-phase modulation in a parabolic index optical fiber

The dynamics that result from the combined effects of spatial diffraction, nonlinearity, and a parabolic graded index for wave propagation in optical fibers are presented. An approximate analytical solution of the nonlinear Schrödinger equation in a graded-index fiber is obtained by using a variational approach. Particular emphasis is put on the variation of both the pulse width and the longitudinal phase delay with the distance of propagation along the fiber.

Fractionated irradiation and early changes in noradrenaline induced potassium efflux (86Rb+) in rat parotid gland

The effects of fractionated irradiation on the electrolyte fluid secretion from rat parotid gland were studied. Secretion was measured as noradrenaline stimulated potassium efflux in vitro with 86Rb+ as tracer for potassium. The irradiation was delivered either as a five-day schedule (total dose 20, 25, 30, 35, 40, 45 Gy) or a two-day schedule (total dose 24, 32 Gy). The noradrenaline stimulated efflux was decreased in comparison with contralateral controls 10 days after the last irradiation. The effect was dose-dependent. Based on the data available, alpha/beta ratio of the used system was calculated to about 20 Gy, which corresponds to other results regarding early radiation effects.

Antibody response against autologous and heterologous isolates of Borrelia burgdorferi in four patients with Lyme neuroborreliosis

Serum and cerebrospinal fluid (CSF) samples from four patients with Lyme neuroborreliosis were analyzed for IgM and IgG antibodies by an indirect enzyme immunoassay with the four patients' own CSF isolate of Borrelia burgdorferi and two tick isolates, strains STG152 and B31, as antigens. No major differences in the antibody response were found comparing autologous and heterologous strains as sonicate antigens, although a tendency towards a stronger response to the autologous isolates was noted in samples from two patients.

Microdialysis of 5-S-cysteinyldopa from interstitial fluid in cutaneous human melanoma transplanted to athymic mice

Microdialysis was investigated as a tool for the determination of the extracellular concentration of the pigment metabolite 5-S-cysteinyldopa in human melanoma transplanted to athymic mice. Histology of the tumour with the microdialysis probes in situ showed no tissue damage. With probes equipped with polycarbonate membranes (20 kD) extraction (relative recovery) was approximately 50% at pH 4.0 and flow rates of 1 microliter/min, but at pH 7.0 recoveries were markedly lower, particularly from serum. In a first series of human melanomas transplanted to athymic mice low concentrations of 5-S-cysteinyldopa were detected in only two out of ten dialysates and were not detected in the other eight. Utilizing devices constructed for comparison of membrane characteristics in vitro we found about 4-fold higher recoveries with cuprophane and polyamide membranes than with polycarbonate membranes. Therefore newly constructed microdialysis probes (CMA/11) with cuprophane membranes were tested in vitro and gave recoveries of 38-48% from Ringer-Acetate solutions and 22-31% from serum, and the pH effects were low. When these probes were utilized in a second series of melanomas transplanted to athymic mice, 5-S-cysteinyldopa could easily be quantified in 10/10 experiments. A steady-state level of the dialysate 5-S-cysteinyldopa concentration was reached after 45 min.

Fibre composition of the ventral roots L7 and S1 in the owl monkey (Aotus trivirgatus)

The ventral roots L7 and S1 of the owl monkey Aotus trivirgatus, were examined by electron microscopy. On average, these roots contain 2950 and 1837 myelinated axons respectively. In both roots the myelinated axons have bimodal size distributions, but the S1 root contains more small myelinated axons. Both roots contain a substantial proportion of unmyelinated axon profiles (UAP). In the L7 root the proportion of UAP decreases as the spinal cord is approached, from 19% distally to 5% in the juxtamedullary rootlets. Unmyelinated and very small myelinated CNS-type axons have not been observed in the L7 transitional region. The average S1 root contains some 40% unmyelinated axons at all examined proximo-distal levels. Unmyelinated/very small myelinated axons are easily found on the CNS side of the S1 transitional region, in direct relation to motoraxon bundles. Bundles of unmyelinated and small myelinated axons occur in the ventral pia mater of both segments. The unmyelinated axons in the L7 root of the owl monkey appear to be arranged like those in the feline L7 ventral root, possibly representing afferents. It is likely that most unmyelinated and small myelinated axons in the ventral root S1 are autonomic efferents.

Structures on the I-A molecule predisposing for susceptibility to type II collagen-induced autoimmune arthritis

The susceptibility to type II collagen (CII)-induced arthritis (CIA) in mice is profoundly influenced by major histocompatibility complex (MHC) class II genes in the H-2 region. Analyses of MHC-congenic strains on the B10 background show that only strains developing an anti-CII antibody response after immunization with autologous CII develop arthritis after induction with CII from various species. The susceptible haplotypes have been found to be H-2q, H-2r, H-2w3 and H-2w17. In addition, these haplotypes respond to different patterns of CII derived from various species suggesting that T cell receptors and CII peptides interact. In contrast, certain haplotypes closely related to H-2q, such as the H-2p and H-2w5 haplotypes, are resistant to induction of CIA and are nonresponders to CII. We have earlier shown that a critical structure on the I-A beta molecule determines the susceptibility differences between the p and q haplotypes. We have now determined the structure of exon 2 of the A beta as well as some of the A alpha genes of the remaining haplotypes in the p, q and r families. The sequences show similarities between the CIA-susceptible haplotypes in the A beta C-terminal part and the A alpha N-terminal part of the first domains forming a large part of the antigenic peptide-binding site. Among the wild mouse-derived haplotypes, the w5 haplotype showed an A beta sequence identical to that of the p haplotype consistent with its nonresponder nature to CII immunization. These findings suggest that (a) structures shared between different class II molecules are of importance for the susceptibility to disease in mouse strains and (b) most likely recognition of different CII peptides is important for development of disease.

Western immunoblot and flagellum enzyme-linked immunosorbent assay for serodiagnosis of Lyme borreliosis

Western immunoblot with a whole-cell lysate was compared with an enzyme-linked immunosorbent assay with a purified flagellum antigen of Borrelia burgdorferi for serodiagnosis of Lyme borreliosis. The assays showed similar sensitivities and specificities in detecting immunoglobulin M and/or immunoglobulin G antibodies in sera from 68 patients with neuroborreliosis and 44 controls with meningitis and encephalitis or with multiple sclerosis. Flagellum enzyme-linked immunosorbent assay is more easily standardized and seems to be a more suitable diagnostic test in a routine laboratory.

Cultivation and characterization of spirochetes from cerebrospinal fluid of patients with Lyme borreliosis

Attempts were made to culture spirochetes from cerebrospinal fluid samples of 105 patients suspected of having Lyme borreliosis with neurological complications. At the final evaluation, only 38 patients fulfilled the criteria of neuroborreliosis. Spirochetes were cultured from cerebrospinal fluid samples of four of these patients. All four patients had pleocytosis in their cerebrospinal fluid and a history of neurological symptoms of only 4 to 10 days in duration. Two of them had no detectable antibodies against any of the isolated spirochetes in their cerebrospinal fluid, both when tested with an enzyme-linked immunosorbent assay and when tested by immunoblotting. An antibody reaction against the homologous isolate that was distinctly stronger than that against the heterologous isolates was found in the serum and cerebrospinal fluid samples from one patient. The cells of the isolates were morphologically similar and showed a very similar protein pattern when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cells of all isolates reacted with the monoclonal antibodies H5332 and H9724, which also react with Borrelia burgdorferi B31, the type strain. One isolate lost a major protein of 23 kilodaltons after subcultivation for 4 months. We conclude that isolation of spirochetes from cerebrospinal fluid might prove successful in clinically selected cases of Lyme borreliosis.

Comparison of flagellum and sonicate antigens for serological diagnosis of Lyme borreliosis

A sonicate antigen and two concentrations of a purified flagellum antigen of Borrelia burgdorferi were compared for serological diagnosis of Lyme borreliosis by an enzyme immunoassay (EIA). Generally, the higher concentration of flagellum antigen was found to be superior to the lower concentration, which was diluted eight times compared to the higher concentration. The diagnostic sensitivity for IgG antibody detection increased from 13% in the sonicate EIA to 31% in the best flagellum EIA assay (p = 0.01) in sera from patients with erythema migrans (n = 70), and from 34% to 55% (p = 0.01) in sera from patients with neuroborreliosis (n = 77). However, the sensitivity for IgG in sera from patients with acrodermatitis chronica atrophicans (n = 20) was high in both assays: 90% in the sonicate EIA compared to 95% in the flagellum EIA. Regarding IgM, there was no significant difference between the sensitivity of the assays in sera from any of the patient groups. The sensitivity values for IgM and IgG in cerebrospinal fluid (CSF) from patients with neuroborreliosis were also without significant differences. Sera and CSF from patients with meningitis/encephalitis of non-Borrelia etiology (n = 35), multiple sclerosis (n = 9) or syphilis (n = 24), served as controls. The flagellum EIA showed a significantly improved specificity for IgG in CSF from controls with syphilis (p less than 0.01). It is concluded that purified Borrelia burgdorferi flagellum antigen is superior to a sonicate antigen, especially for serodiagnosis of the early stages of Lyme borreliosis.

Localization of a critical restriction site on the I-A beta chain that determines susceptibility to collagen-induced arthritis in mice

Type II collagen-induced arthritis (CIA) in mice is an autoimmune experimental model for rheumatoid arthritis. Susceptibility to CIA is associated with certain major histocompatibility complex class II haplotypes. The two very closely related haplotypes H-2q and H-2p differ in susceptibility to CIA. Only mice of H-2q (DBA/1, B10G strains) but not mice of H-2p-expressing strains (like strain B10P) develop CIA and an autoimmune response to type II collagen (CII) after immunization with CII. In contrast to H-2p, the H-2q haplotype does not express I-E molecules. The purpose of the present study was to identify, at the molecular level, the structures on major histocompatibility complex class II molecules determining susceptibility to CIA and CII responsiveness. We first excluded the possible suppressive involvement of Ep or Ap molecules by showing that F1 hybrids between H-2p and H-2q haplotype strains, expressing Ep and Ap, are responders to CII and fully susceptible to CIA. Secondly, because A alpha chains appear identical, we sequenced the A beta first-domain exons of p and q allotypes and found only four diverging amino acids in the predicted amino acid sequence. These variable residues were closely located at positions 85, 86, 88, and 89 at the end of the postulated alpha-helix, which is of importance for interactions with the antigenic peptide and the T-cell receptor. We suggest that this region is a critical major histocompatibility complex restriction site for CIA and CII responsiveness in H-2q mice as compared with H-2p mice. The CIA will now be an excellent autoimmune model for studies on interactions between autoantigenic peptide, autoreactive T cells, and a particular major histocompatibility complex molecule, as has been postulated to be the initial event also in rheumatoid arthritis.

Pharmacokinetics of disodium clodronate after daily intravenous infusions during five consecutive days

The pharmacokinetics of disodium clodronate was studied in six patients, three females and two males with Paget's disease and one male patient with prostatic cancer. The drug was given at a dose of 300 mg/day as a 3-hour infusion for 5 consecutive days. The concentration of the drug in serum and urine was measured by a gas chromatographic method. The peak concentration of disodium clodronate in serum was 5.7 +/- 1.0 micrograms/ml (means +/- SD) for the males and 10.1 +/- 2.8 micrograms/ml for the females. The elimination half-lives of the drug were 0.76 +/- 0.47 h and 1.79 +/- 0.26 h and the total clearances 18.2 +/- 3.3 l/h and 11.5 +/- 1.9 l/h, respectively. During the fifth day both sexes showed similar mean clearances of 11.9 +/- 1.3 l/h and 11.1 +/- 2.5 l/h and half-lives of about 2 h. The renal clearances was 7.3 +/- 0.5 l/h and 5.9 +/- 0.4 l/h for males and females, respectively. The mean urinary excretion of disodium clodronate during the 5-day period was 59.5% in the male patients and 56.0% in the female patients. We concluded that the slow infusion may increase the accumulation of clodronate in the body causing a higher clearance and a lower urine excretion of the drug than seen in earlier studies with faster infusions.

Comparison of Western blot and enzyme-linked immunosorbent assay for diagnosis of Lyme borreliosis

The usefulness of Western blot in the serological diagnosis of Lyme borreliosis was evaluated compared with an ELISA using a whole cell sonicate antigen. Fifty-three of 68 (78%) patients with neuroborreliosis had positive IgM and/or IgG immunoblots and 40 of 68 (59%) had positive IgM and/or IgG ELISA titers in serum. Eight of 44 (18%) controls with meningitis/encephalitis of non-borrelia etiology had positive IgM and/or IgG immunoblots and 4 of 44 (9%) had positive IgM and/or IgG ELISA titers in serum. Western blot was more sensitive than ELISA, the difference being most pronounced in sera from patients with neurological disease for four weeks or less. Both patients and controls lived in an area endemic for Lyme borreliosis and some ELISA negative but Western blot positive controls were thought to have been previously exposed to Borrelia burgdorferi. However, the specificity for current disease was not improved by Western blot. In conclusion, Western blot does not seem to be the method of choice for screening purposes in a routine laboratory but can be used as a complement to ELISA for serodiagnosis in patients with disease of short duration.

Aspects of the diagnosis of Lyme borreliosis

Attempts were made to culture spirochetes from the cerebrospinal fluid of 105 patients with suspected Lyme borreliosis with neurological complications. At the final evaluation, only 38 patients fulfilled the criteria of neuroborreliosis. Spirochetes were cultured from the cerebrospinal fluid of four of these patients. All four had pleocytosis in their cerebrospinal fluid and a history of neurological symptoms of only four to ten days. Two had no detectable antibodies in their cerebrospinal fluid against any of the isolated spirochetes, neither when tested with an ELISA nor by Western blot. A distinctly stronger antibody reaction to the homologous isolate than to the heterologous isolates was found in serum and cerebrospinal fluid from one patient. The cells of the isolates were morphologically similar and showed a very similar protein pattern when analyzed by SDS-PAGE. Cells of all isolates reacted with the monoclonal antibodies H5332 and H9724, which also react with Borrelia burgdorferi isolate B31, the type species. One isolate lost a major protein of 23 kD after subcultivation for four months. We conclude that isolation of spirochetes from cerebrospinal fluid is not suitable as a routine method but might prove successful in clinically selected cases of Lyme borreliosis. The patient antibody response to spirochetal components was analyzed with Western blot. Antibodies to low-molecular components including a major protein with a molecular weight of 21-23 kD, and to a 41-kD major flagellar protein, were the first to appear in serum and in CSF samples. No single band in the immunoblots was found to be specific. By requiring a 41 kD band together with at least one low-molecular band for a positive immunoblot, 53 of 68 (78%) patients with neuroborreliosis had positive IgM and/or IgG serum immunoblots by visual reading of coded material. Western blot was more sensitive than ELISA based on a sonicate antigen which identified 40 of the 68 (59%) patient samples as positive, but not significantly more sensitive than ELISA based on a purified flagellum antigen which identified 50 of 68 (74%). Western blot tended to be more sensitive than the flagellum ELISA regarding sera from patients with neurological symptoms of 2 weeks or shorter duration. However, there was a tendency towards a lower specificity regarding the serological diagnosis of current Lyme borreliosis by Western blot than by sonicate and flagellum ELISAs.(ABSTRACT TRUNCATED AT 400 WORDS)

Evidence for two different classes of redox-active cysteines in ribonucleotide reductase of Escherichia coli

The large subunit of ribonucleotide reductase from Escherichia coli contains redox-active cysteine residues. In separate experiments, five conserved and 2 nonconserved cysteine residues were substituted with alanines by oligonucleotide-directed mutagenesis. The activities of the mutant proteins were determined in the presence of three different reductants: thioredoxin, glutaredoxin, or dithiothreitol. The results indicate two different classes of redox-active cysteines in ribonucleotide reductase: 1) C-terminal Cys-754 and Cys-759 responsible for the interaction with thioredoxin and glutaredoxin; and 2) Cys-225 and Cys-439 located at the nucleotide-binding site. Our classification of redox-active cysteines differs from the location of the active site cysteines in E. coli ribonucleotide reductase suggested previously (Lin, A.-N. I., Ashley, G. W., and Stubbe, J. (1987) Biochemistry 26, 6905-6909).

Collagen induced arthritis as an experimental model for rheumatoid arthritis. Immunogenetics, pathogenesis and autoimmunity

The type II collagen (CII) induced arthritis animal model (CIA) provides opportunities to study the nature of autoimmune reactions leading to arthritis and may be used as a model for rheumatoid arthritis (RA). Thus, in similarity with RA, the CIA model, when induced with autologous CII, shows a chronic and progressive disease course. The susceptibility to both RA and CIA are correlated to the expression of certain MHC class II allotype genes. In both diseases are autoantibodies to CII and rheumatoid factors produced. Immunohistopathology of affected joints show in both diseases a dominance of activated macrophages/fibroblasts with a significant infiltration of activated T cells and an infiltration of granulocytes. We do here suggest that both RA and CIA are dependent on a synergy between delayed type hypersensitivity and immune complex mediated inflammatory mechanisms and that CIA provides opportunities for studies of immunospecific reactions leading to arthritis.

Clothing fasteners for long-term-care patients: evaluation of standard closures and prototypes on test garments

For the elderly long-term-care patient it is of great psychological and practical importance to be able to dress and undress without assistance. However, the design and position of clothing fasteners often lead to a restriction of the functional capacity of the patient. The aim of this study was to facilitate a more independent daily life for long-term care patients. New fasteners were developed in accordance with a user-oriented product development process where a detailed knowledge of the final users and their capacity and limitations, problems, needs and wishes form the basis for further development. In an initial experimental study (I) the practical use of different standard clothing fasteners (button, hook and eye, nylon pressure tape and zipper) was evaluated. Different fasteners and positions are favourable to different patient groups. Wrist angle in different hand positions is crucial for the function of fasteners for persons with reduced hand function. User demands on clothing fasteners were specified and prototypes developed. In a subsequent study (II) an adapted oval button and a 'finger strap' alternative to hook-and-eye were designed and evaluated, together with a standard button. The oval button in combination with a vertical buttonhole improved the function for most patients, and the front position for the fasteners was superior to a diagonal or lateral position on the chest. The finger strap was of advantage to patients with hemiplegia and joint complaints but was difficult for many of the subjects to understand, being a technical innovation.

Radical formation in the dimeric small subunit of ribonucleotide reductase requires only one tyrosine 122

The small subunit of ribonucleoside-diphosphate reductase (EC 1.17.4.1) is a homodimer. Its catalytic site contains one tyrosyl radical, which is localized to Tyr-122 in one of its polypeptide chains. The engineered Tyr-122----Phe protein was used to demonstrate that it is possible to form a correct ferric iron center in vitro in the absence of Tyr-122. Heterodimers, consisting of one Tyr-122-containing polypeptide chain and one Phe-122-containing polypeptide chain, were constructed. The heterodimer population contained one-half the amount of tyrosyl radical as compared to a homodimer with Tyr-122, i.e. every second heterodimer contains a tyrosyl radical. Thus, one Tyr-122 is sufficient for radical formation. Radical-containing heterodimers are catalytically competent.

Clinical manifestations and diagnosis of neuroborreliosis

Lyme borreliosis has in a few years turned out to be a health problem not only in the United States, but also in many European countries. When it affects the nervous system, Lyme borreliosis acts as the great disease imitator. Because of this characteristic it is often difficult to diagnose on clinical grounds. Patients with neuroborreliosis might appear within all medical disciplines. Clinical markers, such as preceding tick bite and/or ECM, are important clues to the diagnosis. Mononuclear pleocytosis and elevated CSF protein are present in most patients with neuroborreliosis. Final evidence for the diagnosis is the demonstration of specific antibodies in serum and/or CSF. Measurement of antibody titers should be carried out in both serum and CSF, since these methods are complementary when trying to obtain a serological diagnosis of neuroborreliosis.

Treatment of Lyme borreliosis with emphasis on neurological disease

We have studied 113 patients with neurologic Lyme borreliosis and meningitis who were treated with intravenous high-dose antibiotics (penicillin G, 12 g, mostly for 14 days in 47 patients; penicillin G, 9 g, mostly for 10 days in 58 patients; doxycycline, 200 mg, in 5 patients; and cefuroxime, 4.5-9 g, in 3 patients). Seventy percent of the patients had peripheral nerve symptoms and 13% had central nervous symptoms. Almost half of the patients were treated more than 4 weeks after the onset of symptoms and 15% of the patients had persisting or progressive symptoms between 4 and 11 months. There seemed to be clinical benefit as well as a decrease of spinal fluid pleocytosis and spinal proteins. No significant symptoms of Herxheimer reaction were demonstrated.

CNS-induced natriuresis during dopamine receptor blockade. Further support for the existence of, at least, two separate natriuretic hormonal systems

Intracerebroventricular (ICV) stimulation with hypertonic sodium chloride solutions has previously shown indications to stimulate the release of a blood-borne natriuretic factor. Sodium excretion in this situation increases in the order of 10-20 times. Acute isotonic volume expansion has shown to be a potent stimulus for endogenous release of the atrial natriuretic factor (ANF). It has also been demonstrated that the natriuretic response to both volume expansion and exogenously applied ANF can be attenuated by the dopamine receptor blocker haloperidol. The present study was performed to investigate if the natriuretic response to ICV stimulation also could be attenuated with haloperidol, thus indicating similar effector mechanisms as for ANF. A first group of anaesthetized animals was, therefore, pre-treated with haloperidol (H) and then ICV stimulated (H-ICV). A second group of animals was subjected to acute isotonic volume expansion (VE, 2% b.w.h.-1) to evoke the documented ANF release. In a third group of animals pre-treatment with haloperidol was followed by volume expansion (H-VE). In the H-ICV group there was a more than 30-fold increase in sodium excretion, due to an increase both in urine flow rate (more than sixfold) and in the urinary concentration of sodium (more than fourfold). Potassium excretion increased more than eightfold, urine osmolality was unchanged, and blood pressure increased by 7%. In the VE group sodium excretion increased more than 18-fold, consequent to large increases in urine flow rate (more than 23-fold), while the urinary concentration of sodium tended to decrease. Potassium excretion increased more than threefold, urine osmolality decreased by 88%, and blood pressure was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Half-site reactivity of the tyrosyl radical of ribonucleotide reductase from Escherichia coli

A C-terminally truncated form of protein B2, the homodimeric small subunit of ribonucleotide reductase from Escherichia coli, was found as the result of an apparently specific proteolysis. Truncated homodimers contain an intact binuclear iron center and a normal tyrosyl radical but have no binding capacity for the other ribonucleotide reductase subunit, protein B1, and are consequently enzymatically inactive. Heterodimers, consisting of one full-length and one truncated polypeptide, formed spontaneously during a chelation-reconstitution cycle and were easily separated from the two homodimeric variants. The heterodimeric form of B2 shows a weak interaction with the B1 subunit resulting in low enzyme activity. Using heterodimers containing deuterated tyrosine on the full-length side and protonated tyrosine on the truncated side, we could demonstrate that the tyrosyl radical was randomly generated in one or the other of the two polypeptide chains of the heterodimeric B2 subunit. The small subunit of ribonucleotide reductase thus conforms to a half-site reactivity.

Fate of haem after parenteral administration of haem arginate to rabbits

Rabbits were injected either intravenously or intramuscularly with [14C]haem arginate and [59Fe]haem arginate (haem 5 mg kg-1). The main part (80%) of AUCINF of labelled haem was associated with the beta-phase, T1/2 being about 6 h. Only 1% of the haem dose had been taken up by the red blood cells. In contrast, the iron moiety from the haem molecule was effectively utilized. Thirty days post-injection of [59Fe]haem arginate, 40% of the dose after intravenous injection and 60% after intramuscular injection was circulating with the red cells. Radioactivity was shown to concentrate in the liver, where haem is mainly metabolized and eliminated. An accumulation of haem in the adrenals was also evident. Haem itself did not concentrate in the bone marrow, and a negligible amount of radioactivity was recovered from brain, implying a poor penetration of the blood brain barrier.

Amantadine for prophylaxis against influenza A

Amantadine, 200 mg daily, for 5 days was used in an attempt to restrict the spread of influenza A in a hospital ward. After index cases of influenza A amantadine was given to 2 patients with clinical symptoms and to 8/10 patients who were not yet ill. No further case of clinical influenza was seen among the patients, but 3 of those receiving amantadine developed subclinical infection. No side effects of amantadine were noted. Amantadine was not given to any of the 23 hospital staff on duty. In this group 8 cases of influenza A appeared, 3 of them during the week after the introduction of amantadine to patients.

Antibiotic usage in surgery in a large teaching hospital

A prevalence study of the antibiotic usage in the surgical departments at the Karolinska Hospital, Stockholm, showed that 126/517 hospitalized patients (24%) received antibiotics and that 100/306 operated patients (33%) received antibiotics. 44 (44%) of the operated patients were given their antibiotics as prophylaxis and 46 (37%) of all patients receiving antibiotics were given them as prophylaxis. Antibiotics were administered intravenously to 35 (28%) patients, orally to 75 (60%), and topically to 16 patients (13%) (eye department only). The most commonly used drugs in prophylaxis were isoxazolylpenicillins and trimethoprim-sulphonamide while cephalosporins accounted for a minor part. In therapy the most commonly used drug was isoxazolylpenicillin, followed by ampicillin derivatives, metronidazole, tetracyclines, trimethoprim-sulphonamide and cephalosporins. The pattern of antibiotic usage differed markedly between departments.

Analysis of pethidine disposition in the pregnant rat by means of a physiological flow model

The disposition of pethidine (meperidine) in the pregnant rat is described by means of a physiological flow model. The model includes arterial and venous blood, brain, fat, fetal, hepatic, intestinal, muscular, pulmonar, and renal tissues. The concentration-time profiles of pethidine calculated by the model are consistent with experimental data, except for the brain and renal tissues, where the model predicts initially higher concentrations. Simulations are carried out to further explore the contribution from different organs on the kinetics in blood and tissues. The tissue-to-blood partition coefficients vary over a range from 5 to 316, where fat has the lowest and liver the highest after a correction is made due to hepatic extraction. Rapid uptake occurs into highly perfused organs such as brain, kidneys, liver, and lungs, followed by fetus, intestines, muscle, and fat. Data indicate no marked membrane resistance to pethidine of the investigated organs, except for fetal tissues, but rather a perfusion-limited uptake. Simulations suggest that muscles and adipose tissue play an important role in the rat, becoming the major reservoir of drug during the intermediate and terminal elimination phase, respectively. Volume of distribution and the biological half-life agree with reported findings. Pethidine is subject to a high systemic blood clearance, which exceeds the total hepatic blood flow in the rat. No degradation of pethidine is found in blood, and therefore a pulmonary expression for pethidine clearance is added as a potential source of pethidine elimination. The elimination of pethidine after a single i.v. bolus does is found to be dependent on simulated changes in cardiac output and hepatic blood flow. A simulation is performed with the scaled model to mimic the human concentration-time profiles in maternal blood and brain tissues and fetal tissue during repetitive doses of pethidine.

Overproduction and purification of the B2 subunit of ribonucleotide reductase from Escherichia coli

The nrdB gene of Escherichia coli, coding for the B2 protein of ribonucleotide reductase, has been cloned in a runaway-replication vector. The runaway derivative pBEU17 carries the promoter-proximal portion of the E. coli alanyl-tRNA synthetase gene and proved useful for expressing cloned genes lacking their native transcription initiation signals. The alaS promoter is located approximately 500 base pairs upstream of a single BamHI restriction endonuclease cleavage site utilized in the construction of an expression recombinant plasmid, pBS1, for the nrdB product. After 5-h thermal induction of cells carrying the runaway recombinant pBS1, protein B2 constituted 40% of the soluble protein fraction of the cells. The high concentration of protein B2 in crude extracts of induced cells has enabled a simplified purification scheme to be developed for production of homogeneous and concentrated B2 preparations. Protein B2 produced from pBS1 is identical to the chromosomally encoded nrdB product of E. coli as regards molecular mass on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, enzyme activity, tyrosine radical content, and structure of the binuclear iron center. Amino acid sequence analysis showed that the two polypeptide chains of protein B2 are identical. They start with an alanine residue, and the first 30 residues confirmed the amino acid sequence predicted from the nucleotide sequence of the nrdB gene, apart from an NH2-terminal processing removal of the initiator methionine.