Biomedical subjects

J Gerhards

Publications and source records attributed to J Gerhards.

8 recordsLinked to original sources

PubMed1999

Theileria parva 104 kDa microneme--rhoptry protein is membrane-anchored by a non-cleaved amino-terminal signal sequence for entry into the endoplasmic reticulum.

The 104 kDa microneme-rhoptry protein (p104) is the only known apical complex organelle-specific protein of Theileria parva. p104 exhibits striking structural similarities to circumsporozoite protein and sporozoite surface protein 2 of Plasmodium yoelii. Their primary sequences contain two hydrophobic segments, located at the amino-and the carboxy-terminus. The p104 amino-terminal hydrophobic region was suggested to be a signal peptide for entry into the endoplasmic reticulum and the extreme carboxy-terminal region to function as a membrane anchor. We have studied the biogenesis of p104 in a cell-free expression system and found that p104 is co-translationally transported into membranes derived from endoplasmic reticulum. The amino-terminal signal peptide is not cleaved off and anchors the protein in the membrane with the carboxy-terminal portion translocated into the lumen. We suggest that in vivo p104 is co-translationally integrated into the membrane of the endoplasmic reticulum, from where it is further transported to the microneme-rhoptry complex. Thus, p104 appears to be a suitable marker to study the development of micronemes and rhoptries in T. parva.

Animals↗

PubMed1994

Comparative analysis of intrathecal antibody synthesis and DNA amplification for the diagnosis of cytomegalovirus infection of the central nervous system in AIDS patients.

We evaluated 49 paired cerebrospinal fluid (CSF) and serum samples of 35 patients infected with the human immunodeficiency virus type 1 (HIV-1) for laboratory evidence of cytomegalovirus (CMV) infection. The patients were grouped according to clinical criteria as probable CMV encephalitis/polyradiculomyelitis, CMV retinitis, cerebral toxoplasmosis, progressive multifocal leukoencephalopathy, HIV-1-related cognitive/motor complex, HIV-1-associated myelopathy, and other neurological diseases. Paired CSF and serum samples were analysed for CMV deoxyribonucleic acid (DNA) by polymerase chain reaction (PCR), quantitative intrathecal synthesis of immunoglobulin G (IgG) antibodies specific for recombinant phosphoprotein 150 (pp150) of CMV and CMV-specific serum IgM. Intrathecal synthesis of pp150-specific IgG was detected in 26% of patients (9/35), serum IgM was found in 23% of patients (8/35), and PCR of CSF was positive in 11% of patients (4/35). Detection of CMV-specific DNA in CSF preceded the intrathecal antibody synthesis in three patients for whom serial samples were available. PCR results of the CSF became negative in one patient with CMV polyradiculomyelitis after successful therapy with 9-[2-hydroxy-1-(hydroxymethyl) ethoxymethyl] guanine (DHPG). PCR has a higher diagnostic specificity in the acute phase of CMV infection than intrathecal antibody synthesis. The serum IgM response to CMV cannot be used to monitor a compartmentalized immune response in the central nervous system while an intrathecal immune response seems to be associated with recovery either spontaneously or as a result of treatment.

AIDS-Related Opportunistic Infections↗

PubMed1994

Sequence and expression of a 90-kilodalton heat-shock protein family member of Theileria parva.

A Theileria parva specific full-length cDNA clone, T7, which encodes a protein with more than 60% homology to heat shock protein 90 (hsp90) of other organisms, has been identified. T7 appears to be a single copy gene. The gene is expressed as a protein of 87 kDa in both the sporozoite and schizont stages of T. parva. The protein was not found in the piroplasm stage, although the corresponding transcript was detected, suggesting post-transcriptional regulation of the gene. In the schizont stage the T7 protein is upregulated upon heat shock and localized in the cytoplasm.

Amino Acid Sequence↗

PubMed1994

Acute diffuse leukoencephalitis in HIV-1 infection.

The clinical, neuroradiological, and cerebrospinal fluid findings of a case with acute diffuse leukoencephalitis, a demyelinating disease associated with human immunodeficiency virus infection of the brain, is reported. The patient presented with acute tetraparesis as the primary manifestation of a previously symptom free HIV infection. Cerebrospinal fluid analysis showed enhanced inflammatory abnormalities with high concentrations of P24 antigen. MRI showed diffuse white matter hyper-intensities in both hemispheres. In the follow up over 22 months, the neurological deficits disappeared after antiretroviral treatment in good correlation with improvements in MRI as well as in inflammatory cerebrospinal fluid abnormalities.

AIDS Dementia Complex↗

PubMed1992

Loceryl nail lacquer--realization of a new galenical approach to onychomycosis therapy.

Loceryl nail lacquer was developed to provide the effective antifungal drug, amorolfine, in a once-weekly dosage regimen combined with a convenient mode of application. Traditional formulations such as creams and nail solutions do not fulfil these requirements because they are wiped or washed off very rapidly. Amorolfine nail lacquer builds a non-water-soluble film on the nail plate, and this film remains in place for 1 week. The film contains a high concentration of amorolfine and forms a depot from which the drug is delivered and which allows the drug to permeate the nail plate. The film-forming polymer and the solvent were optimized for drug release, stability, and convenience of application (drying time, no gloss, transparency). In preclinical development, porcine hoof horn was used as a screening model to differentiate between formulations and dosage strengths with respect to the penetration rate. A high drug concentration of 11.72 micrograms/specimen (10 mm in diameter) was reached in the hoof horn after 6 h, increasing to 39.5 micrograms/specimen within 7 days, the maximum duration of the investigation. The drug concentration achieved was far above its minimum inhibitory concentration. Furthermore, the penetration model clearly indicated that amorolfine crossed the horn barrier and was found in the moistened gauze which simulated the nail bed. After a 7-day penetration period, 1.8% of the applied dose (500 micrograms) was available under the nail.

Administration, Topical↗

PubMed1989

Isolation and characterization of RNA from the intracellular parasite Theileria parva.

Using a rapid procedure to isolate schizonts of the intracellular parasite Theileria parva from infected bovine lymphocytes, we have prepared parasite RNA that is more than 90% pure. Characterization of this schizont RNA has revealed the presence of two ribosomal RNA species of 3.3 kb and 1.8 kb and a third non-adenylated abundant RNA species of 1.9 kb. In vitro translation of the isolated schizont mRNA has identified about 200 parasite specific polypeptides, only a few of which could be detected by translation of mRNA from infected host cells. By analysing the kinetics of liquid hybridization of schizont mRNA with its homologous complementary DNA the nucleotide sequence complexity of the abundant class of the parasite mRNA has been estimated to be 1.7 x 10(3) kb. Assuming a number average size of 2 kb per mRNA molecule this would represent 4000 transcripts for all abundance classes of the schizont mRNA. Using the same technique we estimate that approximately 10% of the mRNA isolated from infected lymphocytes were transcripts from the parasite genome. We conclude that the low number of parasite specific translation products in the mRNA from infected lymphocytes and the low number of parasite proteins detected in isolated schizonts reported previously is due to the low abundance of the parasite transcripts rather than a low number of expressed parasite genes.

Animals↗

PubMed1987

Electronic determinants of the anti-inflammatory action of benzoic and salicylic acids.

Ab initio, quantum chemical methods have been used to study the possible modes of binding of benzoic and salicylic acids to cyclooxygenase which lead to their anti-inflammatory action. The biological data for this work were obtained from full dose response curves of the inhibitory potency of active compounds on prostaglandin production in mouse macrophages. With the help of simple regression analysis the most important reactivity indices are identified and the ionization state of the active species is discussed. From the physical significance implied by these regressions and an analysis of the electronic charge distributions of the frontier orbitals, a two-way charge transfer model is proposed. The electrostatic potentials of active and inactive congeners have been analyzed, and it is shown that an electrostatic orientation effect seems to make an important contribution to the binding of the active molecules to their receptor site. An electrostatic potential model of the binding site is proposed, and it is shown that this model is able to rationalize the source of activity or inactivity of the investigated substances.

Animals↗

PubMed1986

A PCILO study of the pharmacologically active conformation of local anesthetics of the procaine type. Conformational analysis and complex formation of protonated 2-diethylaminoethyl-acetate with formate anion.

To rationalize and improve receptor selectivity of local anesthetics of the procaine type a dynamic two-center model of the pharmacon-receptor interaction is suggested. A quantum chemical study within the Perturbation Configuration Interaction using Localized Orbitals (PCILO) approximations is carried out to find indications for a conformational change of this flexible drug from its thermodynamically preferred conformation to its pharmacologically active one. For this purpose, the pharmacon-receptor interaction is simulated quantum chemically by the interaction of the local anesthetic model compound 2-diethylaminoethyl-acetate (acetylcaine) with the one-center receptor model formate anion and the two-center receptor model gamma-aminobutyric acid in its zwitterionic form. In the present study, the conformational behaviour of acetylcaine is investigated in detail, confirming this molecule to be an appropriate model for procaine. In its formate complex the preferred conformation of acetylcaine is still retained with regard to the torsional angle of the [OCCN] fragment. Artefacts of the in-vacuo condition of the calculation are discussed. In view of the proposed interaction model, the importance of the first interaction of acetylcaine with the anionic receptor site is found to be in the fixation of the local anesthetic at the receptor surface, due to the long-range character of this interaction. Furthermore, an increased polarity of the carbonyl group of acetylcaine due to this interaction may enhance the proposed second interaction with the receptor.

Anesthetics, Local↗