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Biomedical subjects

J Pohl

Publications and source records attributed to J Pohl.

At least 91 records · Page 5Linked to original sources
PubMed1993

The antitumor activity of the platinum complex D-17872 is associated with tumor cell differentiation.

The novel cisplatin analogue D-17872 was studied for its anticancer activity using in vivo and in vitro preclinical models. The compound at the sublethal dose of 215 mg/kg (ca. 50% of the approximate LD50) induced no nephrotoxic effect strong enough to increase the blood urea level in rats. It had good in vivo antitumor efficacy against murine P388 (max. ILS: D-17872 132%, cisplatin 55%) and L1210 leukemia (max. ILS: D-17872 43%, cisplatin 38%), L5222 leukemia of the rat (max. ILS: D-17872 163%, cisplatin 163%) and murine B16 melanoma. Activity against P388 leukemia substantially exceeded that of cisplatin. Moreover, the M5076 reticulum cell sarcoma implanted into the subrenal capsule and the DMBA-induced mammary tumor of the rat were inhibited by D-17872 to a greater extent than by cisplatin (min. T/C: D-17872 -3%, cisplatin 11%). Using clonogenic microassays, D-17872 was active in vitro against a variety of human and rodent tumor cell lines, albeit at higher concentrations than cisplatin (IC50 values: D-17872 2.6-12.7 mumol/l, cisplatin 0.13-0.42 mumol/l). Apart from its cytotoxic action it was able to induce in vitro differentiation of the human HL-60 and K562 and of the murine M1-T22 cell lines, while cisplatin induced differentiation only in the HL-60 cell line. Thus D-17872 exhibited a pharmacological and toxicological profile different from that of the parent compound. The results suggest that induction of differentiation contributes to the antineoplastic efficacy of this novel cisplatin derivative.

Animals↗
PubMed1993

Transcription of retinoic acid receptor genes in transgenic mice increases CD8 T-cell subset.

Retinoic acid (RA), a vitamin A derivative is known to have a number of effects on the immune system such as inducing cytotoxic T-lymphocytes in vivo and inducing the rejection of skin grafts. However, the molecular mechanisms of these actions are unclear. The retinoic acid receptors which belong to the steroid/thyroid receptor superfamily, are known to bind to regulatory elements of certain genes thereby regulating gene transcription. To determine if expression of retinoic acid receptors in vivo under normal physiological conditions is also regulating genes involved in immunological function, we assayed the human retinoic acid receptor gamma gene driven by a T-cell specific lck-promoter in transgenic mice. Using FACS analysis, we showed that mice expressing the RAR gamma-transgene had significantly increased numbers of CD4-/CD8+ cells compared to controls.

Animals↗
PubMed1993

Bactericidal activities of synthetic human leukocyte cathepsin G-derived antibiotic peptides and congeners against Actinobacillus actinomycetemcomitans and Capnocytophaga sputigena.

Actinobacillus actinomycetemcomitans and Capnocytophaga spp. are gram-negative bacteria implicated in the etiology of periodontal disease (particularly in individuals with neutrophil defects) and life-threatening systemic infections. They are resistant to many antibiotics of microbial origin but are sensitive to the nonoxidative microbicidal action of neutrophils. These organisms are susceptible to the microbicidal effect of cathepsin G but are killed by two distinct mechanisms. The purpose of this study was to assess their sensitivity to the antibiotic effects of IIGGR and HPQYNQR, antimicrobial peptides derived from human neutrophil cathepsin G. The efficacies of the synthetic peptides IIGGR and HPQYNQR were tested by single-dose screening, dose-response, and kinetic assays against three representative strains (each) of A. actinomycetemcomitans and Capnocytophaga spp. and one strain of Eikenella corrodens. Strains of A. actinomycetemcomitans were sensitive to IIGGR and HPQYNQR at equal concentrations (wt/vol), whereas strains of Capnocytophaga and E. corrodens were more sensitive to IIGGR than to HPQYNQR. These differential antibiotic effects occurred over both time and dose ranges too narrow to be of therapeutic significance but are consistent with the premise that cathepsin G kills these oral bacteria by two distinct mechanisms. Except for IVGGR, congeners of IIGGR, including AIGGR, IAGGR, IIAGR, IIGAR, IIGGA, IQGGR, ILGGR, and I-norleucyl-GGR (InLGGR), were microbicidal at 500 micrograms/ml. IIGGR-amide exhibited no antibiotic activity. The D-enantiomer of IIGGR, DIDIGGDR, was as potent as IIGGR itself. APQYNQR exhibited antibiotic activity but somewhat less than HPQYNQR. We conclude that charge distribution, but not chirality or net charge, is an important determinant in the antibiotic efficacy of IIGGR. Moreover, peptide antibiotics derived from cathepsin G may have therapeutic value against periodontal gram-negative, facultative bacteria.

Actinobacillus Infections↗
PubMed1993

Synthetic peptides of human lysosomal cathepsin G with potent antipseudomonal activity.

Enzymatically active and inactive (diisopropylfluorophosphate-treated) cathepsin G exerted antibacterial action in vitro against Staphylococcus aureus, whereas only enzymatically active cathepsin G displayed bactericidal action against Pseudomonas aeruginosa. In order to further test the requirement for protease activity for the antipseudomonal action of cathepsin G, synthetic peptides spanning the full-length mature protein were prepared and examined for antibacterial action. Surprisingly, three structurally distinct peptides that correspond to residues 61 to 80, 117 to 136, and 198 to 223 within the full-length protein were found to exert potent antipseudomonal action (> 4.5 logs of killing at 500 micrograms/ml) against P. aeruginosa ATCC 27853 and four mucoid clinical isolates. Only the peptide (CG117-136) corresponding to residues 117 to 136 (117-RPGTLCTVAGWGRVSMRRGT-136) within cathepsin G exerted antibacterial action against the gram-positive pathogen S. aureus. The antipseudomonal action of CG117-136 was rapid and could be inhibited either by increasing concentrations of NaCl or by 0.5 mM MgCl2 plus 0.5 mM CaCl2, and these conditions appeared to reduce binding of the peptide to whole bacteria. Variants of peptide CG117-136 lacking either a hydrophobic N-terminal domain or a positively charged C-terminal domain were found to have significantly less antipseudomonal action than CG117-136. The antibacterial capacity of the all-D-enantiomeric form of peptide CG117-136 was found to be identical to that of the all-L-peptide, suggesting that the mechanism of killing does not require the recognition of a target site possessing a chiral center.

Amino Acid Sequence↗
PubMed1993

Heterogeneity of the purified extracellular aspartyl proteinase from Candida albicans: characterization with monoclonal antibodies and N-terminal amino acid sequence analysis.

Three dominant proteins (41, 48, and 49 kDa) were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in purified preparations of the extracellular aspartyl proteinase (AP) of Candida albicans. All three proteins bound to the specific carboxyl proteinase ligand, pepstatin A, and were associated with maximum AP activity. The N-terminal amino acid sequence for the 48- and 49-kDa proteins matched that reported by others for AP, whereas the sequence for the 41-kDa protein was unique and was not homologous to any known protein. Time course studies demonstrated the simultaneous presence of all three proteins, supporting evidence that the 41- and 48-kDa proteins were not breakdown products of AP. Previous studies did not detect carbohydrate in SDS-polyacrylamide gels of purified AP preparations stained with periodic acid and silver, making glycosylation an unlikely explanation for the observed differences in the molecular masses of the proteins. Some monoclonal antibodies directed against the 49-kDa protein reacted with the 41- and 48-kDa proteins, indicating cross-reactive epitopes. Other monoclonal antibodies, however, reacted only with the 49-kDa protein. We conclude that three pepstatin A-binding proteins occur in purified AP preparations: two have the same amino acid N terminus as that reported for AP, whereas the third has a unique sequence. All three proteins should be considered when undertaking studies to determine the role of AP in candidal pathogenesis or when preparing specific antibodies for antigen capture assays.

Amino Acid Sequence↗
PubMed1993

Immunogenicity of the Plasmodium falciparum asexual blood-stage synthetic peptide vaccine SPf66.

The immunogenicity of the cocktail vaccine SPf66 against Plasmodium falciparum was investigated in rabbits, monkeys, and human volunteers. This polymerized peptide vaccine incorporates a portion of each of the 35-kD, 55-kD, and 83-kD blood-stage proteins, linked by an amino acid sequence reproducing one repeat from the circumsporozoite protein of P. falciparum. Results from this study show that vaccination with this vaccine molecule elicited high titers of antibodies to SPf66 and its constituents, but these antibodies did not correlate with regular or sensitive indirect fluorescent antibody (IFA) titers to blood-stage malaria parasites. However, rabbits injected with individual peptides produced antibodies with low affinity to indefinite parasite structures by immunoelectron microscopy, and rabbits injected with SPf66 had high antibody titers against the peptide (NANP)40. Consequently, these anti-SPf66 serum samples recognized P. falciparum sporozoites in the IFA. Such reactivity was not observed in monkeys or human volunteers vaccinated with SPf66. In addition, SPf66 components were recognized by antibodies induced by natural infection in humans and by laboratory-monitored infections in Aotus monkeys. These results suggest that this vaccine candidate merits further developmental work to better define immune response elicited by the copolymer to the parasite.

Adolescent↗
PubMed1993

[Management of children with prenatally diagnosed urinary tract abnormalities].

Between 1984 and 1991, antenatal ultrasound scanning detected urinary tract malformations in 126 infants, who were investigated and treated postnatally in the childrens' hospital of the Westfälische Wilhelms-University Münster. 10 out of 126 children with urogenital changes, died in the first hours after birth, due to pulmonary hypoplasia (Potter's sequence), 1 further infant died later after cardiac operation, and another died of megacystic-megaureter-hypoperistaltic-syndrome. In the first months after birth 71 (61%) of 116 infants underwent urological surgery; 12/116 infants (10.3%) had severe bilateral kidney changes, some of them with severe deficiency of amniotic fluid before birth. 6/116 infants (5.2%) had chronic renal insufficiency, 2 of them will have to be dialyzed in early childhood and longterm, 14 patients (12%) are threatened by chronic renal failure. 14 patients (12%) developed severe arterial hypertension, all had to be treated with antihypertensive drugs, in 5 of them hypertension subsided after unilateral nephrectomy, another five had transient hypertension, but four require continued medical treatment. We describe the prenatal ultrasound findings, compared them with diagnosis after birth, illustrate diagnostics, plans of therapy, urological surgical interventions and nephrological consequences. Benefits and limitations of antenatal ultrasonography for the detection of urinary tract malformations and the treatment of those malformations before and after birth are discussed. In utero diagnosis of severe urinary tract abnormalities allows treatment of these infants immediately after birth, furthermore the prevention of severe infections, additional damage of renal tissue, and early diagnosis and treatment of arterial hypertension and metabolic imbalances caused by chronic renal insufficiency in early childhood.

Female↗
PubMed1992

Unique autolytic cleavage of human myeloperoxidase. Implications for the involvement of active site MET409.

Myeloperoxidase (MPO) is a functionally important component of the normal human neutrophil host defense system. This enzyme possesses a dimeric structure composed of two heavy subunit (55-63 kDa)/light subunit (10-15 kDa) protomers, each of which is associated with a heme-like prosthetic group. In addition, MPO species of approximately 38 and 22 kDa have been reported by many different investigators, but their nature and mode of origin are not understood. In the present study, we demonstrate that when MPO is heated under nonreducing, denaturing conditions, these two species are produced via a novel autolytic cleavage of the heavy subunit. The 38-kDa species was isolated by fast-protein liquid chromatography and identified by sequencing as the carboxyl-terminal portion of the heavy subunit, and the cleavage was shown to occur exclusively between Met409 and Pro410. In order to further characterize this unusual cleavage reaction, the 22-kDa species was digested with endoproteinase Asp-N, and the peptide corresponding to its carboxyl terminus was isolated and analyzed by sequencing and mass spectrometry. These data indicated that during cleavage of the heavy subunit, Met409 was converted to homoserine lactone. Thus, the cleavage appeared to formally resemble the cyanogen bromide-dependent cleavage of Met-X peptide bonds. Recent x-ray crystallographic data for canine MPO have indicated that Met409 is in close proximity to the heme-like prosthetic group of MPO. Our studies suggest that interaction of Met409 with this group leads to the formation of a methionyl sulfonium derivative which undergoes intramolecular rearrangement with subsequent peptide cleavage under nonreducing conditions. This derivative may be, at least in part, responsible for the unusual spectral characteristics and enzymatic properties of the enzyme. The primary structure of the 22-kDa MPO species is also reported, and direct evidence is provided for asparagine-linked oligosaccharide moieties at two of the three predicted glycosylation sites.

Amino Acid Sequence↗
PubMed1992

Cloning and expression of an NADP(+)-dependent alcohol dehydrogenase gene of Entamoeba histolytica.

Ethanol is the major metabolic product of glucose fermentation by the protozoan parasite Entamoeba histolytica under the anaerobic conditions found in the lumen of the colon. Here an internal peptide sequence determined from a major 39-kDa amoeba protein isolated by isoelectric focusing followed by SDS/PAGE was used to clone the gene for the E. histolytica NADP(+)-dependent alcohol dehydrogenase (EhADH1; EC 1.1.1.2). The EhADH1 clone had an open reading frame that was 360 amino acids long and encoded a protein of approximately 39 kDa (calculated size). EhADH1 showed a 62% amino acid identity with the tetrameric NADP(+)-dependent alcohol dehydrogenase of Thermoanaerobium brockii. In contrast, EhADH1 showed a 15% amino acid identity with the closest human alcohol dehydrogenase. EhADH1 contained 18 of the 22 amino acids conserved in other alcohol dehydrogenases, including glycines involved in binding NAD(P)+ as well as histidine and cysteine residues involved in binding the catalytic zinc ion. Like the T. brockii alcohol dehydrogenase, EhADH1 lacked a 23-amino acid stretch present in other alcohol dehydrogenases that includes four cysteines that bind a second noncatalytic zinc ion. An EhADH1-glutathione-S-transferase fusion protein showed the expected NADP(+)-dependent alcohol dehydrogenase and NADPH-dependent acetaldehyde reductase activities. The enzymatic activities of the EhADH1 fusion protein were inhibited by pyrazole and 4-methylpyrazole.

Alcohol Dehydrogenase↗
PubMed1992

RXR alpha, a promiscuous partner of retinoic acid and thyroid hormone receptors.

Retinoic acid receptor (RAR), thyroid hormone receptor (T3R) and vitamin D3 receptor (VD3R) differ from steroid hormone receptors in that they bind and transactivate through responsive elements organized as direct rather than inverted repeats. We now show that recombinant RAR and T3R are monomers in solution and cannot form stable homodimeric complexes on their responsive elements. Stable binding of the receptors to their responsive elements requires heterodimerization with a nuclear factor. This auxiliary factor is tightly associated with RAR and T3R in the absence of DNA and co-purifies with both receptors. As demonstrated by extensive purification, the same auxiliary factor is required for stable DNA binding of RAR as for that of T3R; the factor also facilitates the formation of a stable VD3R-DNA complex. The auxiliary factor is identical to the retinoid X receptor alpha (RXR alpha) by biochemical and functional criteria. The identification of RXR alpha as a dimerization partner for the RARs, T3Rs and VD3R has important implications as to the function of these receptors and their ligands in development, homeostasis and neoplasia.

Animals↗
PubMed1992

Multichannel electromyographic observations in spasmodic dysphonia patients and normal control subjects.

Spasmodic dysphonia is primarily a disorder of vocalization. Increasing evidence, however, suggests that individuals with this disorder comprise a heterogeneous population characterized by abnormal motor control throughout the vocal tract. Multichannel simultaneous electromyography was performed on 11 spasmodic dysphonia patients and 10 normal awake subjects to investigate both the distribution of neuromotor abnormality within the vocal tract (eg, intrinsic and extrinsic laryngeal muscles, tongue, and palate) and the contribution of activation of higher central nervous system centers to observed abnormality. Experimental tasks ranged from vegetative (quiet breathing) to simple linguistic (short sentences). Digitized electromyographic signals were analyzed to compute the amplitude envelope and extract a set of parameters that represent amplitude characteristics. Electrode insertions were cross-validated by quantitative analysis of patterns of activation across selected reference tasks and by traditional qualitative methods. Between-group differences were found for measures of normalized median and peak token amplitudes. These differences are both task- and measure-dependent. Results highlight the complex and interactive effects of muscle, task, and quantitative measures on between-group differences.

Adult↗
PubMed1992

[Arterial hypertension. Prevention in infants with congenital urinary tract malformations].

Eighty-nine newborns and infants with congenital urinary tract malformations were treated in the childrens' hospital of the Westfälische Wilhelms-University from 1986 to 1989. Twenty patients of this group (22.5%) developed severe hypertension requiring treatment within the first year of life. Mean age of diagnosis of hypertension was 5 months (range 0.5-12 months). Median values for blood pressure at time of diagnosis were 138 mmHg (range 120-170) for systolic and 92 mmHg (range 80-110) for diastolic values. Six patients showed characteristic symptoms for hypertension such as restlessness, sweating and sleep disorders. Plasma levels of renin were obtained in 12 of 20 patients. Five patients had raised plasma renin levels. All patients with a severe hypertension were treated with one to several antihypertensive drugs. Risk factors for the development of severe renal hypertension in early infancy are cystic renal malformation, vesico-ureteral reflux, obstructive uropathy and to our experience also short term percutaneous nephrostomy in obstructive uropathy in particular in connection with pyelonephritis. Hypertension can still appear after the successful surgical correction of urinary obstruction. We describe the group of patients with severe hypertension in our study group; diagnostic principles and our therapeutic approach are explained. We conclude that early diagnosis of severe hypertension and consecutive treatment are important in infants with congenital urinary malformations.

Antihypertensive Agents↗
PubMed1991

Peptide-binding specificity of the molecular chaperone BiP.

Members of the heat-shock protein family (hsp70s) can distinguish folded from unfolded proteins. This property is crucial to the role of hsp70s as molecular chaperones and is attributable to the amino-acid specificity of the peptide-binding site. The specificity for peptide ligands is investigated using a set of peptides of random sequence but defined chain length. The peptide-binding site selects for aliphatic residues and accommodates them in an environment energetically equivalent to the interior of a folded protein.

Adenosine Triphosphatases↗
PubMed1991

Human lysosomal cathepsin G and granzyme B share a functionally conserved broad spectrum antibacterial peptide.

Human neutrophil lysosomal cathepsin G (cat G) exerts broad-spectrum antibacterial action in vitro against Gram-negative and -positive bacteria independent of its serine protease activity. We recently determined that an internal peptide of cat G (HPQYNQR), obtained after digestion of cat G with clostripain, possessed broad-spectrum antibacterial action in vitro, displaying an ED50 of 5 x 10(-5) M. In order to evaluate the structure-antibacterial properties of this peptide, synthetic variants with single alanine substitutions at each position were prepared and tested for antibacterial action. We found that alanine substitution for His-1 or Tyr-4, or certain modifications of the His-1 side chain, produced nonbactericidal peptides. A hexapeptide lacking the COOH-terminal Arg-7 but not a pentapeptide lacking both Gln-6 and Arg-7 possessed in vitro bactericidal activity. Interestingly, the cat G bactericidal peptide displays similarity to sequences within other serine proteases, notably the proposed cytotoxic granzymes present in the cytolytic granules of human and mouse cytotoxic T lymphocytes. We now report that an internal peptide of one human granzyme (granzyme B) with the sequence of HPAYNPK also displays bactericidal action in vitro. Our results suggest that an internal antibacterial domain among human serine proteases cat G and granzyme B has been functionally conserved through evolution perhaps for the purpose of host defense against microbial pathogens and targets of cytotoxic T lymphocyte killing.

Amino Acid Sequence↗
PubMed1991

Investigation into the immunological effects of miltefosine, a new anticancer agent under development.

Miltefosine is the prototype of alkylphosphocholines, a new class of anticancer agents related to alkyl-lysophospholipids. These agents were considered to possess potent immunomodulatory properties. Miltefosine was highly active against the human KB tumour xenograft in nude mice, leading to growth inhibition as well as regression of large established tumours, which suggested that its mode of action was not mediated by the T cell system. In vivo natural killer cell activity was measured by chromium release of YAC-1 cells using spleen cells from treated animals as effector cells. Miltefosine had no significant effect on YAC-1 cytolysis. Similarly, the compound did not induce cytotoxic spleen cells against KB target cells. The results were identical when spleen cells from tumour-bearing animals were used. Humoral antibody production in rats following sheep red blood cell immunization was not changed by miltefosine pretreatment. Finally, the in vitro phagocytic activity of mouse bone marrow macrophages was not stimulated but rather inhibited in a dose-dependent manner. In conclusion, there is no experimental evidence that the miltefosine action is mediated by the host immune system and no major immunotoxicity was observed.

Animals↗
PubMed1991

Child sexual abuse prevention: evaluation and one-year follow-up.

Because of the high incidence and negative psychological consequences of child sexual abuse, prevention programs have been developed and implemented nationwide. Few programs, however, have been comprehensively evaluated. In this multimodal study, a 3-session adaptation of the Feeling Yes, Feeling No curriculum was provided to 286 third and fourth graders from four schools whose responses were compared to 113 delayed-treatment control children from two schools. Program impact was assessed using a knowledge scale, the State-Trait Anxiety Inventory for Children, a videotape vignettes measure, a parent questionnaire, and disclosure data. Treatment children exhibited significantly greater knowledge and better ability to discriminate safe from unsafe situations on the video measure than control children at posttesting. These gains were maintained at 6-week follow-up testing. There were no differences in treatment and control children's self-reported anxiety or parents' reports of negative emotional/behavioral consequences, which were minimal. Over 5% of participating children reported ongoing or past sexual abuse. In the One-Year Follow-Up Study, children's knowledge gains and prevention skills scores on the video measure were maintained at one-year follow-up. A 1-session "booster shot" program further enhanced children's safety discrimination skills on the video measure.

Adaptation, Psychological↗
PubMed1991

In vivo measurement of force in the ureter. I. Basics of a new measurement principle.

A new device for the simultaneous in vivo measurement of pressure and developed force in the ureter is introduced. The 5-French catheter was cystoscopically inserted into the ureters of 12 dogs under anesthesia. The forms of the peristaltic waves for pressure and force show considerable differences. A basal force analogous to the basal pressure is only rarely measurable. During the systole, the developed force describes the pure muscle contraction process. The results are dependent on the location of the probe. Our new method is able to give information about the extent to which a ureter possesses the capacity to effectively close its lumen. This function, which is so decisive in urinary transport, can be determined not only qualitatively but also quantitatively.

Animals↗