Characterization of the gltF gene product of Escherichia coli

The glt operon of Escherichia coli comprises the structural genes for the glutamate synthase subunits (gltB and gltD) and gltF, whose product was previously suggested to have regulatory functions. The A/T-rich region between gltD and gltF contains a weak promoter and a translation initiation site for gltF. The GltF protein is preceded by a signal peptide, which is cleaved off during export into the periplasmic space. A gltF::Km(R) insertion mutant was constructed and shown here to have no detectable phenotype with respect to amino acid utilization or ammonium transport. Thus, GltF is apparently not involved in regulation of nitrogen catabolism.

[Treatment with Kava--the root to ocombat stress]

Kava-kava (Piper methysticum), a shrub which grows on the islands of the Pacific Ocean, contains the so-called kavapyrones as active substances; these have been pharmacologically investigated in detail and are comparable with the benzodiazepine tranquilizers with regard to their mode and strength of action. The good tolerance and absence of both the soporific effect and risk of dependence should be emphasized. The present article describes the origin and history of the kava plant as well as its pharmacology, action, possibilities for therapeutic use, and significance in medical practice. Also discussed are the advantages of the standardized kavapyrone complex of active substances as a modern phyto-anxiolytic and daily tranquilizer for nervous anxiety, tension, and agitation states.

[What is the value of determining immunoreactive GHRH in acromegaly?]

Acromegaly is usually due to autonomous, excessive secretion of growth hormone from a pituitary adenoma. One would expect growth hormone-releasing factor (GHRH) in these patients to be suppressed. In the available literature referring to acromegaly, immunoreactive GHRH levels were determined in 259 acromegalic patients. When growth hormone was measured simultaneously, no correlation was found between serum growth hormone and plasma GHRH concentrations, irrespective of whether the acromegalic patients were treated or not. A possible explanation for this finding might be the lack of a feedback regulation between plasma growth hormone and GHRH. Also, since growth hormone is secreted in a pulsatile fashion the interpretation of single growth hormone values can be difficult. IGF I, which correlates well with mean growth hormone production, may therefore represent a more valuable criterion for the assessment of activity and GHRH plasma levels in acromegalics. However, no study has yet been performed to elucidate the relationship between GHRH and IGF I in acromegaly. To examine this relationship we measured the concentration of plasma GHRH and IGF I in 18 treated patients with acromegaly (age range 32-64 years median 50.5 years; median follow-up 6.5 years, range 3 months to 33 years). All immunoreactive GHRH levels were within the limits described as normal in the literature (mean +/- SD 22.89 +/- 2.72 pg/ml, range 19-28 pg/ml). The IGFI level was 396.78 +/- 224.26 ng/ml (mean +/- SD, range 71-876 ng/ml; reference ranges, age group 25-39 years: 114-492 ng/ml; 40-54 years: 90-360 ng/ml; > 55 years: 71-290 ng/ml). We found no correlation between IGF I and GHRH concentrations (r = 0.17). We therefore conclude that measuring plasma GHRH is not useful in the evaluation of the activity or therapy of acromegaly but may be helpful in its differential diagnosis since a massive elevation of GHRH is typically associated with the ectopic GHRH syndrome, a rare cause of acromegaly.

Effects of nitrogen dioxide exposure on Clara cell proliferation and morphology

The present study was performed to relate Clara cell proliferation and Clara cell morphology to duration and intensity of nitrogen dioxide (NO2) exposure as a model of lung injury in rats. Male Sprague-Dawley rats were exposed to 5, 10 and 20 ppm NO2 for three (short term exposure) and 25 days (long term exposure). Epithelial proliferation was immunohistochemically assessed by BrdU-incorporation into the bronchial and bronchiolar epithelium. Clara cell specific 10 kD protein was detected using an antibody versus recombinant protein. Following short term exposure Clara cells showed a significant alteration of their morphology: the cells lost the apical intraluminal projections, and the damaged epithelium was covered by a layer of CC10 reactive material. After long term exposure the Clara cell morphology was indistinguishable from that of unexposed controls. In all short term exposure groups cellular proliferation was higher in the bronchiolar epithelium than in the bronchial epithelium. Whereas short term exposure to 5 ppm NO2 sufficed to induce a maximum epithelial proliferation of the bronchiolar epithelium, long term exposure to 5 ppm NO2 yielded no significant increase in the epithelial proliferation, a finding reflecting the adaptation of the airway epithelium to oxidative stress. Long term exposure to 10 and 20 ppm NO2 resulted in a dosilinear increase of cell proliferation in the bronchial and bronchiolar epithelium. Double labelling of CC10 and BrdU showed that BrdU uptake and hence proliferation were restricted to Clara cells. We conclude that changes of the Clara cell morphology are closely related to the extent of inhalative stress and functional status of the Clara cell. The results are in keeping with the assumption that the Clara cell exerts progenitor cell functions in the airway epithelium.

The functional use of the reciprocal hip mechanism during gait for paraplegic patients walking in the Louisiana State University reciprocating gait orthosis

Reciprocally linked orthoses used for paraplegic walking have some form of linkage between the two hip joints. It has been assumed that flexion of the swinging leg is driven by extension of the stance leg. The aims of this study were to investigate the moments generated around the hip joint by the two cables in a Louisiana State University Reciprocating Gait Orthosis (LSU-RGO). Six (6) subjects were recruited from the Regional Spinal Injuries Centre at Southport, who were experienced RGO users. The cables were fitted with strain gauged transducers to measure cable tension. Foot switches were used to divide the gait into swing and stance phases. A minimum of 20 steps were analysed for each subject. Moments about the hip joint for each phase of gait were calculated. There were no moments generated by the front cable in 4 of the subjects. In only 2 subjects did the cable generate a moment that could assist hip flexion during the swing phase. These moments were very low and at best could only have made a small contribution to limb flexion. The back cable generated moments that clearly prevented bilateral flexion. It was concluded that the front cable, as used by these experienced RGO users, did not aid flexion of the swinging limb.

Applications of neural network analyses to in vivo 1H magnetic resonance spectroscopy of epilepsy patients

A total of 67 in vivo water-suppressed proton magnetic resonance spectra of the temporal lobes were recorded from 15 patients with long standing temporal lobe epilepsy and 13 healthy volunteers. Conventional data analysis indicated slightly lower N-acetyl aspartate levels in epileptic patients compared with controls. For further analysis of data, a spectral region (4.0-1.5 ppm) was used as input for artificial neural network analysis. Correct classification of spectra was obtained in 66 out of 67 cases, disregarding from which side of the brain the spectra were recorded. The ability of the trained network to recognize spectra recorded both contalaterally and ipsilaterally to the epileptic focus strongly indicates bilateral metabolic changes. Artificial neural networks could also be trained to recognize whether the spectra were recorded from the ipsilateral or contralateral side of the epileptic focus, indicating that neural network analysis of in vivo proton MR spectra can be used as an additional tool for pre-surgical lateralization of seizure foci.

Vertical distribution of methanogens in the anoxic sediment of Rotsee (Switzerland)

Anoxic sediments from Rotsee (Switzerland) were analyzed for the presence and diversity of methanogens by using molecular tools and for methanogenic activity by using radiotracer techniques, in addition to the measurement of chemical profiles. After PCR-assisted sequence retrieval of the 16S rRNA genes (16S rDNA) from the anoxic sediment of Rotsee, cloning, and sequencing, a phylogenetic analysis identified two clusters of sequences and four separated clones. The sequences in cluster 1 grouped with those of Methanosaeta spp., whereas the sequences in cluster 2 comprised the methanogenic endosymbiont of Plagiopyla nasuta. Discriminative oligonucleotide probes were constructed against both clusters and two of the separated clones. These probes were used subsequently for the analysis of indigenous methanogens in a core of the sediment, in addition to domain-specific probes against members of the domains Bacteria and Archaea and the fluorescent stain 4', 6-diamidino-2-phenylindole (DAPI), by fluorescent in situ hybridization. After DAPI staining, the highest microbial density was obtained in the upper sediment layer; this density decreased with depth from (1.01 +/- 0.25) x 10(10) to (2.62 +/- 0.58) x 10(10) cells per g of sediment (dry weight). This zone corresponded to that of highest metabolic activity, as indicated by the ammonia, alkalinity, and pH profiles, whereas the methane profile was constant. Probes Eub338 and Arch915 detected on average 16 and 6% of the DAPI-stained cells as members of the domains Bacteria and Archaea, respectively. Probe Rotcl1 identified on average 4% of the DAPI-stained cells as Methanosaeta spp., which were present throughout the whole core. In contrast, probe Rotcl2 identified only 0.7% of the DAPI-stained cells as relatives of the methanogenic endosymbiont of P. nasuta, which was present exclusively in the upper 2 cm of the sediment. Probes Rotp13 and Rotp17 did not detect any cells. The spatial distribution of the two methanogenic populations corresponded well to the methane production rates determined by incubation with either [14C]acetate or [14C]bicarbonate. Methanogenesis from acetate accounted for almost all of the total methane production, which concurs with the predominance of acetoclastic Methanosaeta spp. that represented on average 91% of the archaeal population. Significant hydrogenotrophic methanogenesis was found only in the organically enriched upper 2 cm of the sediment, where the probably hydrogenotrophic relatives of the methanogenic endosymbiont of P. nasuta, accounting on average for 7% of the archaeal population, were also detected.

Different cumulative pregnancy rates in patients with repeated IVF- or ICSI cycles: possible influence of a male factor

The low rate of ongoing pregnancies in IVF cycles leads to a high number of repeated cycles in couples with previously failed attempts. Therefore it would be helpful to have a prediction about the chance of becoming pregnant in a repeated cycle. In a retrospective study the data of about 4246 cycles were analysed. Because the pregnancy rates in IVF- and ICSI cycles are generally different, these two groups were distinguished between and the outcome in patients with one, two or more attempts was analysed. The rate of ongoing pregnancies per patient was lower after IVF (24.9%) than after ICSI (32.9%), but was similar or even slightly increased in patients with more than one attempt. On the other hand, there was a high pregnancy rate with ICSI in the first two cycles (35.9%), but patients with more than two ICSI cycles had a significantly lower chance of becoming pregnant (20.7%). Factors that are known to influence the pregnancy rate, such as stimulation protocol, oocyte quality or number of transferred embryos, were similar in all groups. However, significantly reduced embryo quality with successive cycles was only observed in ICSI patients. There might be a negative selection of patients with poor embryo quality and previously failed attempts after ICSI, possibly due to an andrological factor. The differences between IVF- and ICSI patients are based on treatment indications, and andrological diseases are the predominant indication for ICSI. Although no correlation was found between changes in conventional sperm parameters and number of treated cycles, there might be a subgroup of andrological patients selected by repeatedly failed ICSI cycles. Chromosomal or genetic disturbances in spermatozoa of this subgroup could be the reason for failure.

In vitro assembly properties of wild-type and cyclophilin-binding defective human immunodeficiency virus capsid proteins in the presence and absence of cyclophilin A

The cellular protein cyclophilin A (CypA) binds specifically to the human immunodeficiency virus type 1 (HIV-1) capsid (CA) protein and is incorporated into HIV-1 particles at a molar ratio of 1:10 (CypA/CA). Structural analysis of a CA-CypA complex suggested that CypA may destabilize interactions in the viral capsid and thus promote uncoating. We analyzed the influence of CypA on the in vitro assembly properties of wild-type (WT) CA and derivatives containing substitutions of Gly89 in the Cyp-binding loop. All variant proteins were significantly impaired in CypA binding. In the presence of CypA at a molar ratio of 1:10 (CypA/CA), WT CA assembled into hollow cylinders that were similar to those observed in the absence of CypA but slightly longer. Higher CypA concentrations inhibited cylinder formation. Variant CA proteins G89L and G89F yielded similar cylinders as the WT protein but were significantly more resistant to CypA. Cryoelectron microscopic analysis of WT cylinders assembled in the presence of CypA revealed direct binding of CypA to the outer surface. Electron diffraction patterns generated from these cylinders indicated that CypA causes local disorder. The addition of CypA to preassembled cylinders had little effect, however, and cylinders were only disrupted when incubated with a threefold molar excess of CypA for several hours. These results suggest that CypA does not efficiently destabilize CA interactions at the molar ratio observed in the virion and therefore is unlikely to serve as an uncoating factor.

Immunohistological analysis of cytokine expression in human osteoarthritic and healthy cartilage

OBJECTIVE

To investigate osteoarthritic cartilage in comparison to normal cartilage in humans for the presence of the most relevant cytokines/growth factors known to be important for degradation and formation of new cartilage.

METHODS

Cartilage from knee or hip joints was obtained from 10 patients with osteoarthritis (OA) and from 7 age matched control patients with intact cartilage. Additionally, normal cartilage from 2 young patients (12 and 17 years old) was obtained after knee traumas. Immunohistological staining of cartilage sections was performed using antibodies for the following cytokines/growth factors: tumor necrosis factor alpha (TNF-alpha), interleukin 1alpha (IL-1alpha), IL-1beta, interferon-gamma, IL-6, IL-4, IL-10, transforming growth factor beta1 (TGF-beta1), insulin-like growth factor I (IGF-I), IGF-II, platelet derived growth factor AA (PDGF-AA), and PDGF-BB.

RESULTS

Immunohistochemical stainings were positive for all cytokines in OA cartilage, while only a faint or no staining was found in healthy cartilage. Activated chondrocytes expressing most of the cytokines were located in the middle and partly in the lower layer of cartilage, with the exception of IGF-I, which was expressed exclusively in the upper cartilage layer close to the surface. More chondrocytes stained positive for TNF-alpha than for IL-1, and expression of the degrading cytokine TNF-alpha was inversely correlated to the expression of the regulatory cytokines IL-4, IL-10, and TGF-beta.

CONCLUSION

The most relevant cytokines known to be involved in cartilage metabolism are produced by chondrocytes themselves. They are upregulated in OA cartilage, suggesting that they serve some regulatory function and could be a target for future treatment.

Enhanced transport of nanoparticle associated drugs through natural and artificial membranes--a general phenomenon?

The transport of nanoparticle associated drugs, [75Se]norcholestenol, captopril, methylene blue, hydrocortisone, doxorubicin, and dalargin was determined by permeability measurements in two chamber side by side diffusion cells using cellulose acetate, silicone rubber, pig small intestine, or hairless mice skin as membranes. Solutions of free drugs served as controls. The permeabilities depended on the physico chemical properties of the drugs which governed both, drug interaction with the nanoparticles as well as with the membranes. Consequently, the influence of dilution of the nanoparticle or free drug preparations on permeabilities was complex. With the exception of [75Se]norcholestenol the permeabilities were higher with free drugs than after binding to nanoparticles. The permeabilities of the membranes decreased in the order cellulose acetate, pig small intestine, silicone rubber, and hairless mouse skin.

Differential surface expression of HLA-DRB1 and HLA-DRB4 among peripheral blood cells of DR4 positive individuals

Increasing interest in the functional consequences of differential expression of MHC class II molecules prompted us to examine the surface expression of HLA class II molecules on fresh peripheral blood mononuclear cells. Differential regulation of DR4 and DRB4 was shown for peripheral blood monocytes. In addition, DR4 expression is upregulated on B cells of patients suffering from chronic inflammation and is reduced under prednisolone-treatment. The expression levels of total DR molecules on a given cell type are almost identical comparing different haplotypes among non-RA controls, suggesting that the alpha-chain determines the level of surface expression. The present findings fit the hypothesis that the differential expression of HLA class II molecules is involved in regulation of the immune response and may thus contribute to determining susceptibility to immunological diseases.

Characterization of human T-cell leukemia virus type I integrase expressed in Escherichia coli

The C-terminal part of the pol gene of the human T-cell leukemia virus type I (HTLV-I) is predicted to encode the integrase (IN) of the virus; however, this protein has not yet been detected in virions or infected cells. We expressed the putative IN from an infectious molecular clone of HTLV-I in Escherichia coli. Comparison with protein resulting from coexpression of HTLV-I protease (PR) and Pol in insect cells indicated that the bacterially expressed protein is identical with or very similar to IN released from a PR-Pol precursor by proteolytic cleavage. HTLV-I IN was purified from E. coli under native conditions. The protein behaved like a dimer in size-exclusion chromatography. It carried out activities characteristic of retroviral IN with high efficiency, displaying a strong preference for U5-derived vs. U3-derived sequences in the processing and strand-transfer reactions. In the disintegration reaction, HTLV-I IN not only accepted the double-stranded branched substrate corresponding to the product of a strand-transfer reaction, but was also able to carry out a phosphoryl transfer on a branched molecule with a single-stranded or a single adenosine overhang.

[Indication for and performance of articular cartilage drilling using the Pridie method]

Articular cartilage has only a small capacity for regneration. This makes the repair of articular surfaces difficult. In 1959 Pridie described his method of resurfacing osteoarthritic knee joints. This operation is still in widespread use today. Pridie introduced the principle of drilling exposed subchondral bone with the objective of encouraging a fibro-cartilaginous repair. The newly formed fibrocartilaginous layer that develops over the lesion in osteoarthritis may be enough to decrease patients symptoms. Bone drilling into the subchondral layer is also effective in promoting healing of osteochondrosis dissecans. The choice of the treatment should be based on factors such as age of the patient, serverity of symptoms, activity level and functional demands on the joint, site and stage of the lesion. The drilling operation remains useful in osteoathritis and osteochondrosis dissecans.

Modulating the Th1/Th2 balance in inflammatory arthritis

The balance between Th1 and Th2 cells regulates the choice between inflammatory and antibody-mediated immune responses. To an increasing extent this balance is thought to involve the participation of antigen-presenting cells, rather than the entirely autonomous activity of T cells and their cytokines. Here we survey current opinion concerning the working of this balance, and its condition in rheumatoid arthritis and the other inflammatory arthritides. The contrast between Lyme arthritis and reactive arthritis is particularly illuminating, since one is triggered by extracellular and the other by intracellular infection. We describe current approaches to the modulation of this balance. Guided by the principles that genetic polymorphism is likely to identify relevant genes, that any cytokine gene picked up by a virus must matter and that natural immunosuppressive activity at mucosal surfaces should be worth exploiting, we identify as particularly worthy of attention: (i) IL-10, (ii) inhibitors of IL-12 production, (iii) inhibitors of CD40 ligand expression and (iv) oral and nasal tolerance. Other protective T cell subsets are touched on, and the impact of oligonucleotide arrays mentioned.

A comparison of psychological and pharmacological treatment of pediatric migraine

A comparison was carried out of the efficacy of psychological and drug treatments for children with migraine. Forty-three children aged between 8 and 16 years (mean age: 11.3 years) who suffered from migraine received either progressive relaxation or cephalic vasomotor feedback, both with stress management training, or metoprolol, a beta-blocker. Psychological treatment was administered in ten sessions lasting six weeks and the drug treatment lasted ten weeks. Relaxation and stress management training reduced the headache index (frequency x intensity of headache episodes), more effectively than metoprolol with cephalic vasomotor feedback and stress management training in between. An overall improvement over time was found with regard to frequency and intensity of headache episodes and analgesics intake. When comparing pre- to post-treatment data, children treated with relaxation training improved significantly in headache frequency and intensity, whereas those treated with cephalic vasomotor feedback improved significantly in headache frequency and duration as well as mood. The clinical improvement was stable at an 8-months follow-up.

The spatial distribution of pulmonary lesions in severe ARDS. An autopsy study of 35 cases

The present study was undertaken in order to describe the local distribution and temporal course of pulmonary lesions in severe ARDS. We investigated a total of 35 patients (22 females), ranging in age from 2 to 51 years, who suffered from ARDS III and IV and were treated by extracorporeal CO2 removal and low frequency positive pressure ventilation (ECCO2-R). The extent of acute and chronic diffuse alveolar damage was assessed on histologic gross sections in the ventral, central and dorsal zone of the upper and lower lobes. The lesions showed a characteristic uniform distribution. Areas with chronic DAD were predominantly situated in the ventral portions of the upper lobes. Acute DAD predominated in the dorsal and basal areas of the lung. The extent of acute and chronic DAD was virtually independent of the duration of disease. Hemorrhage occurred at the interface zone between chronic and acute DAD and made up a significant volume portion of the lung tissue, ranging between 8% (lower lobes) and 42% (upper lobes). We conclude that the progression of acute DAD to chronic DAD is mainly determined by local factors (hydrodynamic and hydrostatic forces, intraalveolar pressure) that differ within the lung, whereas the duration of disease plays a minor role. Parenchymal hemorrhage occurs at the interface between areas of acute and chronic DAD and may therefore primarily be due to an increased susceptibility of the pulmonary parenchyma to mechanical stress.

A 5'-3' exonuclease activity involved in forming the 3' products of histone pre-mRNA processing in vitro

Histone RNA 3' processing in vitro produces one or more 5' cleavage products corresponding to the mature histone mRNA 3' end, and a group of 3' cleavage products whose 5' ends are mostly located several nucleotides downstream of the mRNA 3' end. The formation of these 3' products is coupled to the formation of 5' products and dependent on the U7 snRNP and a heat-labile processing factor. These short 3' products therefore are a true and general feature of the processing reaction. Identical 3' products are also formed from a model RNA containing all spacer nucleotides downstream of the mature mRNA 3' end, but no sequences from the mature mRNA. Again, this reaction is dependent on both the U7 snRNP and a heat-labile factor. Unlike the processing with a full-length histone pre-mRNA, this reaction produces only 3' but no 5' fragments. In addition, product formation is inhibited by addition of cap structures at the model RNA 5' end, indicating that product formation occurs by 5'-3' exonucleolytic degradation. This degradation of a model 3' product by a 5'-3' exonuclease suggests a mechanism for the release of the U7 snRNP after processing by shortening the cut-off histone spacer sequences base paired to U7 RNA.

Effect of air pollutants on the pulmonary surfactant system

Air pollutants have been recognized to influence the structure and function of the surfactant system. Agents that have received the most attention include ozone, nitrogen dioxide, hyperoxia, diesel exhaust, tobacco smoke, silica and fibrous materials such as asbestos. The deleterious effects of air pollutants on the surfactant system depend on the size of the agent, on its solubility in aqueous solutions and chemical reactivity and on its concentration and the duration of exposure. Hereby the following general rules apply: the smaller the agent's size and the less water soluble the pollutant is, the greater the tendency to reach the alveoli during breathing. In addition, the reactivity also determines the depth of penetration into alveoli. Compounds with high reactivity such as O3, which also fulfil the earlier rules, will react with the upper respiratory tract compared with compounds with slightly reduced reactivity, such as NO2, which will penetrate the alveoli. The common consequence of exposure to air pollutants is an accumulation of surfactant phospholipids and surfactant-specific proteins in the bronchoalveolar lavage fluid. These components also are structurally altered, mainly by oxidant gases, resulting in impairment of their biological activity. Thus, for surfactant phospholipids, there is impaired adsorption to the air-liquid interface due to oxidation of their fatty acids. Also, surfactant protein A, regarded as a modulator of the surfactant system, shows impaired functions after exposure to oxidants. It is likely that in addition to the effects described in this review not all effects are known because the molecular effects of several key components (e.g. SP-B and C) have not been well studied.