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Biomedical subjects

P Engel

Publications and source records attributed to P Engel.

At least 73 records · Page 4Linked to original sources
PubMed1993

Calmodulin expression during proliferative activation of human T lymphocytes.

We have investigated the levels of calmodulin mRNA species and calmodulin protein during proliferation of human T lymphocytes. Quiescent lymphocytes expressed the 1.7 kb transcript of CaM I, the 1.4 kb of CaM II and the 2.3 kb of CaM III. Phytohaemagglutinin added to peripheral blood lymphocytes induced DNA replication which started at 48 h and reached a maximum at 72 h after activation. All the species of calmodulin mRNAs, including the 4.0 kb transcript of CaM I and the 0.8 kb of CaM III which were not detected in quiescent cells, increased during lymphocyte proliferation. At 72 h after activation, the increase of CaM I and CaM II transcripts were found to be 2-fold whereas CaM III mRNAs increased 9-fold. The cellular content of calmodulin protein was also found to increase during proliferation and calmodulin accumulations in cytosol and nuclei of activated cells were observed. Two calmodulin binding proteins of 180 and 170 kD were found to increase in the nuclei of proliferating lymphocytes, whereas on the contrary 3 other calmodulin binding proteins of 110, 62 and 60 kD decreased during proliferation.

Antibodies, Monoclonal↗
PubMed1993

Growth rate of acoustic neuroma expressed by Ki-67 nuclear antigen versus symptom duration.

The growth rate of acoustic tumors varies widely. An immunohistochemical study with Ki-67 monoclonal antibody was performed on a random sample of 21 acoustic neuromas. The tumors belonged to 2 well-defined groups: 1 with a short duration of preoperative symptoms (< 1 year) and 1 with a long duration of preoperative symptoms (> 5 years). The tumors were of small to medium size (7 to 27 mm), and no large, cystic, or Recklinghausen tumors were included. The tumor proliferative fraction expressed by monoclonal antibody Ki-67 was determined. The results revealed a significant relation between the tumor proliferative fraction and symptom duration. Tumors with a high proliferative status had a short preoperative symptom duration, while tumors with a low proliferative status had a long symptom duration. The clinical implications of these results are discussed.

Adult↗
PubMed1993

Peliosis of the spleen associated with a paraganglioma. Case report.

We report a case of splenic peliosis imitating metastases on CT. The patient was a 44-year-old man who previously had a retroperitoneal paraganglioma surgically removed. Peliosis must be considered a potential differential diagnosis of hypodense foci of the spleen seen on CT.

Adult↗
PubMed1992

Impaired post-transcriptional expression of interleukin-2 receptor in pokeweed mitogen-activated T cells.

The expression and role of interleukin-2/interleukin-2 receptor (IL-2/IL-2R) system in the pokeweed mitogen (PWM)-induced T cell mitogenesis was studied. In the absence of monocytes (Mo), both soluble and Sepharose-bound PWM fail to induce T cell mitogenesis even when exogenous IL-2 or IL-1 or IL-1 + IL-2 or IL-4 are also present. In the presence of Mo, PWM stimulation of T lymphocytes (highly depleted of B lymphocytes) induces as much IL-2 mRNA as phytohemagglutinin (PHA), but results in higher and persistent IL-2 levels in culture supernatants despite the concomitant T cell mitogenesis, suggesting that PWM-activated T cells do not utilize the IL-2 they produce. Confirming this notion, Mo-dependent PWM-preactivated T cells, as compared to PHA-preactivated ones: (a) failed to consume exogenous IL-2 and their mitogenic response did not increase upon exposure to exogenous IL-2; (b) exhibited very low numbers of high-affinity IL-2R; and (c) showed lower expression of IL-2R p55 and undetectable expression of IL-2R p75 on their surface. Moreover, the PWM-induced T cell mitogenesis was not inhibited by anti-IL-2 or CD25 antibodies and only partially (50%-60%) inhibited by cyclosporin A, while these treatments abrogated the PHA-induced one. PWM-activated T cells, as compared to the PHA-activated ones, exhibited as high (p55) or even higher (p75) mRNA expression of both IL-2R p55 and p75 subunits. The possibility that PWM interferes with IL-2R subunits once expressed on the T cell surface was excluded. Thus, intracellular PWM-related events are likely to impair IL-2R expression post-transcriptionally. Possible explanations for this effect and its relation with the capacity of PWM to induce T cell-dependent B cell differentiation are discussed.

Cyclosporine↗
PubMed1992

Increase of cytokeratin D during liver regeneration: association with the nuclear matrix.

An increase of a 45 kD protein (p45) in the nuclear matrix has been observed when rat liver cells were proliferatively activated in vivo by a partial hepatectomy. The maximal levels of the association of p45 with the nuclear matrix have been detected 24 hr after hepatectomy just at the time when DNA replication is also maximal. By amino acid sequence analysis, immunoblotting and immunocytochemical methods, it has been demonstrated that p45 is identical to rat cytokeratin D. Immunogold staining of nuclear matrix-intermediate filament preparations from cultured hepatocytes indicated that p45 is associated with cytoskeletal filaments that are strongly interconnected to the lamina, whereas no intranuclear localization of the protein has been detected. With an overlay assay a specific binding of labeled p45 to two nonidentified high-molecular weight proteins and also to lamin B has been observed. Northern blot analysis revealed a biphasic pattern of expression of the messenger RNA for cytokeratin D during liver regeneration. A sharp increase in the messenger RNA levels occurred in the prereplicative phase of liver regeneration a few hours before the accumulation of the protein in the nuclear matrix fraction, and a second peak occurred 48 hr after partial hepatectomy.

Amino Acid Sequence↗
PubMed1992

The effects of sauna on tetraplegic and paraplegic subjects.

Six tetraplegic (T) and 4 paraplegic (P) subjects underwent a 20-minute pre sauna phase (30 degrees C DB; 65% RH), and an up to 15-minute sauna (85 degrees C DB; less than 10% RH), followed by a 15 minute post sauna phase (30 degrees C DB; 65% RH). During all phases subjects wore a bathing suit and remained supine on a hospital trolley. Heart rate (HR) and blood pressure (BP) were recorded during all phases. Rectal temperature (Trec) was measured by a probe (AD590) inserted approximately 14 cm into the rectum. Oral temperature (Toral) also utilising (AD590) circuitry was recorded simultaneously with Trec. Skin temperature (Tsk) (AD590) was measured on the head, chest, right thigh and right calf. Forehead sweat rate (SR) was determined from dew point temperature (Tdp). A catheter was inserted into a dorsal hand or foot vein and venous blood was withdrawn at selected times and analysed for haemoglobin (Hb) and haematocrit (Hct), and the separated plasma was analysed for glucose (Glu), sodium (Na+), potassium (K+) and chloride (C1-). Venous blood sampled just prior to entering and just prior to leaving the sauna, was analysed for adrenalin (A) and noradrenalin (NA) using high performance liquid chromatography. For both groups HR rose significantly during the sauna with a significant decline in HR for the P group during the post sauna phase. There were no significant changes in systolic BP for either group. A significant decline in diastolic BP was found for the T group during the post sauna phase. There were no episodes of syncope.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1992

Anaerobic fumarate transport in Escherichia coli by an fnr-dependent dicarboxylate uptake system which is different from the aerobic dicarboxylate uptake system.

Escherichia coli grown anaerobically with fumarate as electron acceptor is able to take up C4-dicarboxylates by a specific transport system. The system differs in all tested parameters from the known aerobic C4-dicarboxylate transporter. The anaerobic transport system shows higher transport rates (95 mumol/g [dry weight] per min versus 30 mumol/g/min) and higher Kms (400 versus 30 microM) for fumarate than for the aerobic system. Mutants lacking the aerobic dicarboxylate uptake system are able to grow anaerobically at the expense of fumarate respiration and transport dicarboxylates with wild-type rates after anaerobic but not after aerobic growth. Transport by the anaerobic system is stimulated by preloading the bacteria with dicarboxylates. The anaerobic transport system catalyzes homologous and heterologous antiport of dicarboxylates, whereas the aerobic system operates only in the unidirectional mode. The anaerobic antiport is measurable only in anaerobically grown bacteria with fnr+ backgrounds. Additionally, the system is inhibited by incubation of resting bacteria with physiological electron acceptors such as O2, nitrate, dimethyl sulfoxide, and fumarate. The inhibition is reversed by the presence of reducing agents. It is suggested that the physiological role of the system is a fumarate/succinate antiport under conditions of fumarate respiration.

Aerobiosis↗
PubMed1992

The muscularis mucosae of the human urinary bladder. Implications for tumor staging on biopsies.

The human urinary bladder wall is traditionally described as being without a muscularis mucosae. A consecutive one year material of 772 bladder biopsies from 171 patients were examined for the proposed presence of lamina muscularis mucosae (MM). MM was observed in 15% of the biopsies and in 35% of the patients and graded into three patterns according to its continuity. Biopsies with transitional cell carcinomas were reviewed in order to find out whether MM-positive biopsies had been staged correctly. The data are discussed in relation to earlier studies on the subject.

Biopsy↗
PubMed1992

Estradiol-promoted accumulation of receptor in nuclei of porcine endometrium cells. Immunogold electron microscopy of resting and estradiol-stimulated cells.

Endometrium was collected by curettage from castrated pigs, either untreated or exposed to estradiol in vivo by intrauterine injection, and processed for electron microscopy. The resin LR Gold was used for embedding, and sections were floated on droplets of 10 nm diameter gold particles, coated with the immunoglobulin-G1 (IgG1) fraction or its Fab2 fragment of a monospecific polyclonal antiserum raised in goats against the C-terminal half of the estradiol receptor. On average, only one gold particle per microns 2 became attached in the cytoplasmic area of untreated cells, whereas four were found over the nuclear area. These figures rose to 2-3/microns 2 and 15-26/microns 2, respectively, within 10 min after exposure to estradiol. The labeling intensities of nuclei in cell clusters and of coprocessed nuclei released from cells ruptured during curettage were identical in all situations. Nuclear pores were frequently tagged after estradiol treatment. The proportions of tagging densities in nuclei of untreated and estradiol-exposed cells corresponded to those of receptor contents measured in extracts of isolated nuclei by ligand binding. This correlation was not seen for the cytoplasmic compartment of untreated cells, the scarce tagging of which is interpreted by hidden antigenic determinants. Our morphological analyses support the conclusions drawn from biochemical data (Sierralta et al., 1992) of an estradiol-promoted translocation of receptor from the cytoplasm into the nucleus.

Animals↗
PubMed1991

Reversible interconversion of the functional state of the gene regulator FNR from Escherichia coli in vivo by O2 and iron availability.

FNR, the gene regulator of anaerobic respiratory genes of Escherichia coli is converted in vivo by O2 and by chelating agents to an inactive state. The interconversion process was studied in vivo in a strain with temperature controlled synthesis of FNR by measuring the expression of the frd (fumarate reductase) operon and the reactivity of FNR with the alkylating agent iodoacetic acid. FNR from aerobic bacteria is, after arresting FNR synthesis and shifting to anaerobic conditions, able to activate frd expression and behaves in the alkylation assay like anaerobic FNR. After shift from anaerobic to aerobic conditions, FNR no longer activates the expression of frd and reacts similar to aerobic FNR in the alkylation assay. The conversion of aerobic (inactive) to anaerobic (active) FNR occurs in the presence of chloramphenicol, an inhibitor of protein synthesis. Anaerobic FNR can also be converted post-translationally to inactive, metal-depleted FNR by growing the bacteria in the presence of chelating agents. The reverse is also possible by incubating metal-depleted bacteria with Fe2+. From the experiments it is concluded that the aerobic and the metal-depleted form of FNR can be transferred post-translationally and reversibly to the anaerobic (active) form. The response of FNR to changes in O2 supply therefore occurs at the FNR protein level in a reversible mode.

Aerobiosis↗
PubMed1989

Myxoid tumours in the temporal bone.

Myxoid tumours have the essential common feature, that they are difficult to remove radically because of their gelatinous consistency. Only one previous report describes a myxoid tumour--a myxoma--located to the temporal bone. This paper presents two such tumours in the temporal bone, a myxoma and an extraskeletal myxoid chondrosarcoma. The clinical and histological features of these tumours and the operative treatment are described and discussed.

Adult↗
PubMed1989

High-performance liquid chromatography separation of nikkomycins X and Z.

A reversed-phase, C-18 HPLC method for separation, with baseline resolution, of the chitin synthase inhibitors nikkomycin X and Z is described. This permits, for the first time, satisfactory identification of nikkomycin X and Z contained in a mixture. The use of 30 mM ammonium formate (pH 4.7) containing the ion-pair agent heptanesulfonic acid (1 mM) was critical for the successful separation of these fungicides.

Aminoglycosides↗
PubMed1989

Cellular activation without proliferation to B cell growth factor and interleukin 2 in chronic lymphocytic leukaemia B cells stimulated with phorbol ester plus calcium ionophore.

Individual leukaemic B cells of chronic lymphocytic leukaemia (CLL) do not proliferate to B cell growth factor (BCGF) or interleukin 2 (IL-2) when co-stimulated with immunoglobulin (Ig) ligands. To exclude possible defective signalling via surface Ig (sIg), phorbol myristate acetate (PMA) plus calcium ionophore (A23187) were used to activate purified CLL B cells and compared with staphylococcal protein A coupled to sepharose beads (Seph-PA). RNA synthesis and phenotypic changes after PMA plus A23187 stimulation indicate that CLL B cells from (10) different individuals are similarly able to undergo the G0 to the G1 phase transition and express surface activation antigens. In contrast, they are variable in the capacity to show DNA synthesis, which occurred in only six out of 10 cases. Even in the presence of BCGF (10%, v/v) or IL-2 (50 U/ml) four out of nine CLL B cells activated with PMA plus A23187 or PMA alone were still unable to proliferate although they were induced to express CD23, 4F2, CD25 and OKT9 antigens by PMA plus A23187. However, PMA plus A23187 induced IgM secretion which increased further in response to IL-2 even in the absence of DNA synthesis. Moreover, in other CLL B cell populations, the unresponsiveness to growth factors upon co-stimulation with Ig ligands (Seph-PA) may simply reflect a defective signalling via sIg cross-linking which can be circumvented by PMA plus A23187 stimulation. Recombinant Interferon-gamma (50 U/ml) failed to affect DNA synthesis and IgM secretion.

B-Lymphocytes↗
PubMed1989

Differential responsiveness of human B lymphocytes to phorbol ester and calcium ionophore based on their state of activation.

For tonsil B cells of a particular high density (below 65% Percoll), both phorbol myristate acetate (PMA) (5 ng/ml) and calcium ionophore A23187 (500 nM) were required to induce RNA synthesis, significant DNA synthesis also occurring in the presence of 12,000 MW B-cell growth factor (BCGF). In contrast, PMA alone, even at 1 ng/ml, was a sufficient stimulus to induce strong DNA synthesis in low-density B cells (45-50% Percoll) and strong proliferative responsiveness to BCGF in intermediate-density B cells (55-65% Percoll). In these latter B-cell populations, A23187 (500 nM), acted synergistically with non-mitogenic PMA doses to induce strong DNA synthesis, the PMA dose required being 5-50 times lower in low-density B cells (0.1-1 ng/ml) than in intermediate-density B cells (5 ng/ml). Preactivation for 30 hr with anti-Ig antibodies plus BCGF, known to drive B cells into late G1, rendered high-density B cells responsive to PMA (1-10 ng/ml) with high, dose-related DNA synthesis. These data indicate that the B-cell mitogenicity of a given nanomolar dose of PMA depends on the more advanced state of activation of B cells. It was also found that the above optimal dose of A23187 (500 nM) paradoxically inhibited the PMA-induced DNA synthesis of low-density B cells and in vitro preactivated high-density B cells. Data obtained with low-density B cells suggest that a calcium influx during the PMA-induced proliferative phase of B cells may provide a negative signal for the DNA synthesis.

B-Lymphocytes↗
PubMed1988

Mutation affecting peptide bond formation in nikkomycin biosynthesis.

Nikkomycin, a nucleoside-peptide analog of UDP-N-acetylglucosamine, is a potent chitin synthase inhibitor produced by the bacterium Streptomyces tendae. The HPLC profile of fermentation products in culture broths of a non-producing mutant, Nik 15, was compared with nikkomycin standards. Nikkomycin C and D, the glycone and aglycone moieties, respectively, of nikkomycin Z accumulated. This indicates the mutation affects the capacity to form a peptide bond between nikkomycin C and D, which is here proposed to be the terminal step in the synthesis of the biologically active nikkomycin Z. This is also the first documented case of a mutation affecting a specific step in nikkomycin biosynthesis.

Aminoglycosides↗