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At least 811 records · Page 45Linked to original sources
PubMedDate not supplied

[Visceral leishmaniasis. Personal observation and review of epidemiology, clinical aspects and therapy].

A 5 year old German girl contracted visceral leishmaniasis during a vacation in Spain, either 32 or 20 month prior to the manifestation of disease. She presented with fever, hepatosplenomegaly and pancytopenia. A bone marrow aspirate proved the diagnosis. Therapy with a pentavalent antimony drug brought about immediate improvement. Visceral leishmaniasis has to be suspected in individuals with fever, hepatosplenomegaly and pancytopenia who have resided in endemic areas (Mediterranean countries, India, East Africa, South America) during the previous years. If untreated, visceral leishmaniasis runs a fatal course. Therefore, early diagnosis by morphological and serological means and specific therapy with pentavalent antimony drugs are mandatory.

Animals↗
PubMed1999

The effect of self-monitoring the INR on quality of anticoagulation and quality of life.

In a prospective cohort study the influence of self-monitoring of the International Normalized Ratio (INR) was examined on 100 consecutive patients for a period of 6 months. Quality of life changed in a positive way. Independence and better organization of vacation and spare time were the most frequently mentioned advantages of the new method. Quality of anticoagulation by using a self-monitoring device was improved compared to the values before using the self-monitoring device. For measuring the INR, the usage of a portable monitor as the primary method can be recommended in selected patients receiving oral long-term anticoagulation.

Anticoagulants↗
PubMed1996

[External ophthalmic myiasis cause by Oestrus ovis (sheep and goat botfly)].

HISTORY AND CLINICAL DATA: The case of a 22-year-old woman is presented. The patient complained of a severe foreign-body sensation, immediately after being back at home from vacation in Greece. The eye showed redness and hyperaemia. The cornea was slightly clouded. On the tarsal plate white larvae of an approximate length of 1.5 mm and width of 0.5 mm were moving. The visual acuity was 1,0 and the inner parts of the eye were clinically inconspicuous. TREATMENT AND FOLLOW UP: The parasites were removed and preserved. After instillation of Betaisodona into the conjunctival sac antibiotics (Aureomycin) were prescribed. After 2 days the clinical signs had disappeared nearly completely. An ENT-examination showed regular findings. The larva was identified as a first-instar larva of Oestrus ovis. This insect causes external ophthalmomyiasis. The larva develops into an adult fly. O. ovis is well known as a parasite in the nasal cavities of domestic sheep and goats. CONCLUSION: The infestation of a human eye with maggots of a fly is a rare disease. The parasites are very mobile and clinical signs are variable. A penetration into the eye is possible. Since people have been travelling more often the infection with parasites has a greater probability, although these insects are living in central Europe and in Germany.

Adult↗
PubMedDate not supplied

[Pappataci fever].

Sandfly fever virus is known to cause pappataci fever. The sandfly fever virus belongs to the Genus Phlebovirus (family: Bunyaviridae) and is endemically found in areas of South Europe, Asia and Africa. In Germany, pappataci fever is only described in connection with travelling to endemic areas. We report on a 15 year-old girl suffering from sandfly fever virus infection after vacation in Turkey. The initial symptoms started with fever for about three days, frontal headache, nausea and arthralgia. After a short time of clinical improvement symptoms recurred and our patient entered hospital with signs of severe meningitis. Liquor analysis showed a lymphocytic meningitis. Due to multiple insect bites on her legs sandfly fever was suspected. Blood analysis confirmed an acute infection with sandfly virus Sicilian from which she completely recovered. ELISA and immunoblot analysis revealed an infection with sandfly virus serotype Sicilian, which was not encountered with meningitis so far. Our case report illustrates that due to increased tourism sandfly fever virus infection has to be considered as a cause of aseptic meningitis in travellers.

Adolescent↗
PubMed1991

[A case of external ophthalmomyiasis].

A 9 year old patient with a right ophthalmomyiasis is presented. The infestation happened in Greece during vacation. The symptoms consisted of conjunctivitis and rinitis. The larvaes were removed from the conjunctiva and specified as larvaes I from Oestrus ovis. The infestation possibilities, different clinical evolutions and therapy are discussed.

Animals↗
PubMed1990

[Vitreoretinal dirofilariasis].

The present paper reports on a 41-year-old patient who complained of moving shadows and impaired vision after vacations in southern Europe and central Africa. On ophthalmoscopic examination the cause was found to be an extremely agile worm, whitish, as thin as an end-artery, and approx. 6 mm long, in front of the macula and later in the vitreous. Following treatment with Hetrazan (diethylcarbamazine) and Mintizol (thiabendazole) the worm could no longer be detected. On the basis of morphologic and chemical studies normal helminth worms were ruled out, as were human filariae. It may be assumed with reasonable confidence that the worm observed was an animal parasite of the genus Dirofilaria.

Adult↗
PubMed1999

Staff perceptions of discharge planning: a challenge for quality improvement.

One hundred staff in three acute care public hospitals were asked about their perceptions of successes and failures of their discharge planning activities. The intention was to highlight ways in which the quality of discharge planning could be improved within the acute hospital setting. Generally staff described failures more commonly than successes, with a number of key failures being identified, including problems associated with vacating beds, lack of appropriate staff, patients and career education about discharge activities, general process issues, problems associated with community service provision and patients who are difficult to discharge. Staff identified the lack of feedback on the outcome of their efforts as a source of frustration and a barrier to improving discharge planning activities. The challenges for improving the quality of discharge planning in the acute hospital setting would appear to be in establishing appropriate structures and processes that promote interaction between staff, patients and community providers, and provide incentives for behavioural change.

Attitude of Health Personnel↗
PubMed2005

Synaptic vesicle recycling studied in transgenic mice expressing synaptopHluorin.

Synaptic vesicles are recycled locally within presynaptic specializations. We examined how vesicles are reused after endocytosis, using transgenic mice expressing the genetically encoded fluorescent indicator synaptopHluorin in subsets of neurons. At both excitatory and inhibitory synapses in cultured hippocampal neurons, newly endocytosed vesicles did not preferentially enter the releasable pool of vesicles. Rather, they entered the reserve pool first and subsequently the readily releasable pool over a period of several minutes. All vesicles in the recycling pool could be accessed by spaced stimuli, arguing against preferential local reuse of the readily releasable vesicles. Interestingly, nearly half the vesicles at excitatory synapses, and a third at inhibitory synapses, could not be recruited for release even by sustained stimuli. We conclude that, at presynaptic terminals in the hippocampus, most vesicles vacate release sites after exocytosis and are replaced by existing vesicles from the reserve pool, placing constraints on kiss-and-run recycling.

Animals↗
PubMed2002

Adjusting the binding thermodynamics, kinetics, and orientation of guests within large synthetic hydrophobic pockets.

Kinetic analysis of the host guest complexation of a large, open molecular basket and a highly complementary adamantoid guest reveals that for these types of systems a dissociative mechanism is in operation. Hence, the resident adamantyl guest must completely vacate the cavity before another guest molecule can move in to replace it. As a result of the rigid nature of the host, the energy barrier to this process is relatively high, about 16 kcal mol(-1) at room temperature. Modifying the cavity of the host by dangling either a methyl group or a hydroxyl group from the portal rim alters the thermodynamic binding profile of these hosts. (1)H NMR shift data analysis also reveals that these functional groups can adjust the orientation that monosubstituted guests adopt within the cavity. Additionally, (1)H NMR studies of the binding of (E)1,4-dibromoadamantane allow the observation of two energetically similar diastereomeric complexes. An examination of this guest binding to the three hosts reveals that the interchange between the isomers is much faster than the entry and egression rates, and that the functional groups at the rim of each cavity influence both the rates of reorientation and the equilibrium relating the isomers.

Binding Sites↗
PubMed2003

An empty Drosophila stem cell niche reactivates the proliferation of ectopic cells.

Stem cells are thought to reside in regulatory microenvironments ("niches") generated by stable stromal neighbors. To investigate the significance of empty niches vacated by stem cell loss, we studied Drosophila ovarioles, which maintain two to three germ-line stem cells in a niche requiring adhesive stromal cap cells and Decapentaplegic signals. After experimentally emptying the germ-line stem cell niche, cap cell activity persists for several weeks. Initially, somatic inner germarium sheath cells enter the empty niche, respond to Dpp, but fail to divide. Subsequently, follicle cell progenitors, including somatic stem cells enter the niche, respond to Dpp, and proliferate as long as cap cells remain. Proliferation requires the normal hedgehog signal of the somatic stem cells as well as proximity to the niche. Thus, empty niches can persist, signal incoming cells, and support ectopic proliferation. Similar events may underlie some disease states.

Animals↗
PubMed2001

Lessons from the past: evolutionary impacts of mass extinctions.

Mass extinctions have played many evolutionary roles, involving differential survivorship or selectivity of taxa and traits, the disruption or preservation of evolutionary trends and ecosystem organization, and the promotion of taxonomic and morphological diversifications-often along unexpected trajectories-after the destruction or marginalization of once-dominant clades. The fossil record suggests that survivorship during mass extinctions is not strictly random, but it often fails to coincide with factors promoting survival during times of low extinction intensity. Although of very serious concern, present-day extinctions have not yet achieved the intensities seen in the Big Five mass extinctions of the geologic past, which each removed > or =50% of the subset of relatively abundant marine invertebrate genera. The best comparisons for predictive purposes therefore will involve factors such as differential extinction intensities among regions, clades, and functional groups, rules governing postextinction biotic interchanges and evolutionary dynamics, and analyses of the factors that cause taxa and evolutionary trends to continue unabated, to suffer setbacks but resume along the same trajectory, to survive only to fall into a marginal role or disappear ("dead clade walking"), or to undergo a burst of diversification. These issues need to be addressed in a spatially explicit framework, because the fossil record suggests regional differences in postextinction diversification dynamics and biotic interchanges. Postextinction diversifications lag far behind the initial taxonomic and morphological impoverishment and homogenization; they do not simply reoccupy vacated adaptive peaks, but explore opportunities as opened and constrained by intrinsic biotic factors and the ecological and evolutionary context of the radiation.

Animals↗
PubMed1988

Lesion-induced plasticity in the second somatosensory cortex of adult macaques.

We have reported that elimination of the representation of any body part in the primary (i.e., postcentral) somatosensory cortex of the adult macaque selectively eliminates the representation of that same body part in the second somatosensory area SII. We now report that, although removal of the entire postcentral hand representation does indeed leave the SII hand representation unresponsive to somatic stimulation initially, 6-8 weeks later this cortex is no longer silent. Instead, most or all of the region that had been vacated by the hand representation is now found to be occupied by an expanded foot representation. This massive somatotopic reorganization, involving more than half the areal extent of SII, exceeds that previously observed in the postcentral cortex after peripheral nerve damage and may reflect a greater capacity for reorganizational changes in higher order than in primary sensory cortical areas.

Animals↗
PubMed1995

The three-dimensional structure of NAD(P)H:quinone reductase, a flavoprotein involved in cancer chemoprotection and chemotherapy: mechanism of the two-electron reduction.

Quinone reductase [NAD(P)H:(quinone acceptor) oxidoreductase, EC 1.6.99.2], also called DT diaphorase, is a homodimeric FAD-containing enzyme that catalyzes obligatory NAD(P)H-dependent two-electron reductions of quinones and protects cells against the toxic and neoplastic effects of free radicals and reactive oxygen species arising from one-electron reductions. These two-electron reductions participate in the reductive bioactivation of cancer chemotherapeutic agents such as mitomycin C in tumor cells. Thus, surprisingly, the same enzymatic reaction that protects normal cells activates cytotoxic drugs used in cancer chemotherapy. The 2.1-A crystal structure of rat liver quinone reductase reveals that the folding of a portion of each monomer is similar to that of flavodoxin, a bacterial FMN-containing protein. Two additional portions of the polypeptide chains are involved in dimerization and in formation of the two identical catalytic sites to which both monomers contribute. The crystallographic structures of two FAD-containing enzyme complexes (one containing NADP+, the other containing duroquinone) suggest that direct hydride transfers from NAD(P)H to FAD and from FADH2 to the quinone [which occupies the site vacated by NAD(P)H] provide a simple rationale for the obligatory two-electron reductions involving a ping-pong mechanism.

Amino Acid Sequence↗
PubMed2000

Structures of recombinant human and mouse NAD(P)H:quinone oxidoreductases: species comparison and structural changes with substrate binding and release.

NAD(P)H/quinone acceptor oxidoreductase (QR1, NQO1, formerly DT-diaphorase; EC ) protects animal cells from the deleterious and carcinogenic effects of quinones and other electrophiles. In this paper we report the apoenzyme structures of human (at 1.7-A resolution) and mouse (2.8 A) QR1 and the complex of the human enzyme with the substrate duroquinone (2.5 A) (2,3,5, 6-tetramethyl-p-benzoquinone). In addition to providing a description and rationale of the structural and catalytic differences among several species, these structures reveal the changes that accompany substrate or cofactor (NAD) binding and release. Tyrosine-128 and the loop spanning residues 232-236 close the binding site, partially occupying the space left vacant by the departing molecule (substrate or cofactor). These changes highlight the exquisite control of access to the catalytic site that is required by the ping-pong mechanism in which, after reducing the flavin, NAD(P)(+) leaves the catalytic site and allows substrate to bind at the vacated position. In the human QR1-duroquinone structure one ring carbon is significantly closer to the flavin N5, suggesting a direct hydride transfer to this atom.

Amino Acid Sequence↗
PubMed2002

Presteady-state analysis of a single catalytic turnover by Escherichia coli uracil-DNA glycosylase reveals a "pinch-pull-push" mechanism.

Uracil-DNA glycosylase catalyzes the excision of uracils from DNA via a mechanism where the uracil is extrahelically flipped out of the DNA helix into the enzyme active site. A conserved leucine is inserted into the DNA duplex space vacated by the uracil leading to the paradigmatic "push-pull" mechanism of nucleotide flipping. However, the order of these two steps during catalysis has not been conclusively established. We report a complete kinetic analysis of a single catalytic turnover using a hydrolyzable duplex oligodeoxyribonucleotide substrate containing a uracil:2-aminopurine base pair. Rapid chemical-quenched-flow methods defined the kinetics of excision at the active site during catalysis. Stopped-flow fluorometry monitoring the 2-aminopurine fluorescence defined the kinetics of uracil flipping. Parallel experiments detecting the protein fluorescence showed a slower Leu(191) insertion step occurring after nucleotide flipping but before excision. The inserted Leu(191) acts as a doorstop to prevent the return of the flipped-out uracil residue, thereby facilitating the capture of the uracil in the active site and does not play a direct role in "pushing" the uracil out of the DNA helix. The results define for the first time the proper sequence of events during a catalytic cycle and establish a "pull-push", as opposed to a "push-pull", mechanism for nucleotide flipping.

Binding Sites↗
PubMed2002

The effect of cytosine methylation on the structure and geometry of the Holliday junction: the structure of d(CCGGTACm5CGG) at 1.5 A resolution.

The single crystal structure of the methylated sequence d(CCGGTACm(5)CGG) has been solved as an antiparallel stacked X Holliday junction to 1.5 A resolution. When compared with the parent nonmethylated d(CCGGTACCGG) structure, the duplexes are translated by 3.4 A along the helix axis and rotated by 10.8 degrees relative to each other, rendering the major grooves more accessible overall. A Ca(2+) complex is seen in the minor groove opposite the junction but is related to the B conformation of the stacked arms. At the junction itself, the hydrogen bond from the N4 nitrogen of cytosine C8 to the C7 phosphate at the crossover in the parent structure has been replaced by a water bridge. Thus, this direct interaction is not absolutely required to stabilize the junction at the previously defined ACC trinucleotide core. The more compact methylated junction forces the Na(+) of the protected central cavity of the nonmethylated junction into a solvent cluster that spans the space between the junction crossover and the stacked arms. A series of void volumes within the methylated and the nonmethylated structures suggests that small monovalent cations can fill and vacate this central cavity without the need to unfold the four-stranded Holliday junction completely.

Base Sequence↗
PubMed2004

Viscosity-dependent relaxation significantly modulates the kinetics of CO recombination in the truncated hemoglobin TrHbN from Mycobacterium tuberculosis.

Kinetic traces were generated for the nanosecond and slower rebinding of photodissociated CO to trHbN in solution and in porous sol-gel matrices as a function of viscosity, conformation, and mutation. TrHbN is one of the two truncated hemoglobins from Mycobacterium tuberculosis. The kinetic traces were analyzed in terms of three distinct phases. These three phases are ascribed to rebinding: (i) from the distal heme pocket, (ii) from the adjacent apolar tunnel prior to conformational relaxation, and (iii) from the apolar tunnel subsequent to conformational relaxation. The fractional content of each of these phases was shown to be a function of the viscosity and, in the case of the sol-gel-encapsulated samples, sample preparation history. The observed kinetic patterns support a model consisting of the following elements: (i) the viscosity and conformation-sensitive dynamics of the Tyr(B10) side chain facilitate diffusion of the dissociated ligand from the distal heme pocket into the adjacent tunnel; (ii) the distal heme pocket architecture determines ligand access from the tunnel back to the heme iron; (iii) the distal heme pocket architecture is governed by a ligand-dependent hydrogen bonding network that limits the range of accessible side chain positions; and (iv) the apolar tunnel linking the heme site to the solvent biases the competition between water and ligand for occupancy of the vacated polar distal heme pocket greatly toward the nonpolar ligand. Implications of these finding with respect to biological function are discussed.

Binding Sites↗
PubMed2005

The position 68(E11) side chain in myoglobin regulates ligand capture, bond formation with heme iron, and internal movement into the xenon cavities.

After photodissociation, ligand rebinding to myoglobin exhibits complex kinetic patterns associated with multiple first-order geminate recombination processes occurring within the protein and a simpler bimolecular phase representing second-order ligand rebinding from the solvent. A smooth transition from cryogenic-like to solution phase properties can be obtained by using a combination of sol-gel encapsulation, addition of glycerol as a bathing medium, and temperature tuning (-15 --> 65 degrees C). This approach was applied to a series of double mutants, myoglobin CO (H64L/V68X, where X = Ala, Val, Leu, Asn, and Phe), which were designed to examine the contributions of the position 68(E11) side chain to the appearance and disappearance of internal rebinding phases in the absence of steric and polar interactions with the distal histidine. Based on the effects of viscosity, temperature, and the stereochemistry of the E11 side chain, the three major phases, B --> A, C --> A, and D --> A, can be assigned, respectively, to ligand rebinding from the following: (i) the distal heme pocket, (ii) the xenon cavities prior to large amplitude side chain conformational relaxation, and (iii) the xenon cavities after significant conformational relaxation of the position 68(E11) side chain. The relative amplitudes of the B --> A and C --> A phases depend markedly on the size and shape of the E11 side chain, which regulates sterically both ligand return to the heme iron atom and ligand migration to the xenon cavities. The internal xenon cavities provide a transient docking site that allows side chain relaxations and the entry of water into the vacated distal pocket, which in turn slows ligand recombination markedly.

Animals↗