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Biomedical subjects

A Richter

Publications and source records attributed to A Richter.

At least 289 records · Page 16Linked to original sources
PubMed1993

Effects of fish oil on rectal cell proliferation, mucosal fatty acids, and prostaglandin E2 release in healthy subjects.

BACKGROUND: Experimental studies have indicated dietary fish oil as a protective agent in colon carcinogenesis. Prostaglandins have been suggested to be involved in this process. In the present study, the effects of fish oil on rectal cell proliferation (i.e., intermediate biomarker of cancer risk), mucosal membrane fatty acids, and prostaglandin E2 (PGE2) release were investigated in 12 healthy volunteers. METHODS: In addition to a controlled basal diet, the test subjects received either fish oil (4.4 g omega-3 fatty acids/day) or corn oil supplements for two 4-week periods in a double-blind, crossover trial. Rectal cell proliferation was determined by bromodeoxyuridine immunohistochemistry and ornithine decarboxylase activity. After 2-hour incubation with bromodeoxyuridine, PGE2 concentration in the incubation medium was measured by radioimmunoassay. Mucosal membrane fatty acids were analyzed by gas chromatography. RESULTS: Bromodeoxyuridine labeling index (9.2% vs. 10.9%; P < 0.05), ornithine decarboxylase activity (19.7 vs. 36.4 pmol.mg protein-1.h-1; P < 0.005), and PGE2 release from rectal biopsy specimens (435.5 vs. 671.5 pg/mg wet tissue; P < 0.05) were significantly lower during the fish oil than the corn oil period, whereas membrane fatty acids were not statistically different. CONCLUSIONS: The results support the hypothesis that dietary fish oil may protect against colon cancer.

Adult↗
PubMed1993

Relative sensitivity of leukemic (CML) and normal progenitor cells to treatment with the photosensitizer benzoporphyrin derivative and light.

Normal bone marrow and peripheral blood committed progenitor cells were found to be significantly more resistant to treatment with the photosensitizer benzoporphyrin derivative (BPD) and white fluorescent light (11 J/cm2) than were clonogenic cells from two cell lines (K562 and EM2) derived from nonremission patients with myelogenous leukemias. Bone marrow and peripheral blood committed progenitor cells from normal donors were also found to be more resistant to this treatment than were equivalent cells from patients with chronic myelogenous leukemia (CML). Normal bone marrow mononuclear cells grown in long-term marrow culture (LTMC) following treatment with BPD and light showed that no differences in stem cell productivity existed between control and treated samples. When bone marrow from CML patients was treated in the same manner, the numbers of progenitors detected in the nonadherent population during culture were greatly reduced compared to control material. Two rounds of PCR using nested primers to detect BCR-ABL mRNA showed that while this treatment significantly decreased the numbers of stem cells bearing the Philadelphia chromosome, it did not eliminate them.

Blood Cells↗
PubMed1993

Occurrence of angina pectoris prior to acute myocardial infarction and its relation to prognosis.

In 917 patients with acute myocardial infarction (AMI) we evaluated the impact of previous angina pectoris on the prognosis. Thirty-four percent of the patients had chronic angina prior to AMI, and 22% had angina pectoris of short duration. Patients with chronic angina pectoris differed from the remaining patients having a more frequent previous history of AMI, diabetes mellitus, hypertension, and congestive heart failure. They less frequently developed a Q-wave AMI, and had smaller infarcts according to maximum serum-enzyme activity as compared with the remaining patients. They had a higher one-year mortality rate (36%) as compared with those having angina pectoris of short duration (22%), and those with no angina pectoris (26%). Their reinfarction rate was also higher (26%) as compared with that in the other two groups (15% and 9% respectively). In a multivariate analysis considering age, sex, clinical history, initial symptoms, initial electrocardiogram and estimated infarct size, previous chronic angina pectoris was not an independent risk factor for death, but was independently associated with the risk of reinfarction (P < 0.001). Among patients with a history of angina pectoris the outcome was related to medication prior to onset of AMI and at discharge from hospital. Patients in whom beta-blockers were prescribed at discharge had a one-year mortality of 13% as compared with 30% in the remaining patients (P < 0.001).

Age Factors↗
PubMed1993

Stable constitutive expression of glycoprotein B (gpUL55) of human cytomegalovirus in permissive astrocytoma cells.

Permanent cell lines showing homogeneous constitutive expression of glycoprotein B (gpUL55; gB) of human cytomegalovirus (HCMV) were selected, in the presence of geneticin, from human astrocytoma cells (U373) after transfection with recombinant pRC/CMV-gB carrying the complete coding sequence for HCMV gB and for aminoglycoside phosphotransferase. The biosynthesis and processing including specific proteolytic cleavage, formation of disulphide-linked oligomers as well as transport of recombinant gB in three of four established transformed cell lines essentially resembled that found in infected parental U373 except for eventual degradation after 2 h of gB synthesis. Analysis of the fourth transformant expressing uncleaved gB suggested that proteolytic cleavage is not required for normal intracellular transport. The stable transformants retained permissiveness for productive superinfection with HCMV. The application of cell lines transformed with mutagenized HCMV gB for the rescue of genetically engineered HCMV mutants is discussed.

Astrocytoma↗
PubMed1993

Modified polyvinyl alcohol-benzoporphyrin derivative conjugates as phototoxic agents.

Photosensitizing and biodistribution characteristics of a photosensitizer (benzoporphyrin derivative, monoacid ring A; BPD) conjugated to a macromolecule (modified polyvinyl alcohol; M-PVA, molecular weight = 10,000) were tested in vitro and in vivo. Modified PVA was loaded with BPD at molar ratios 1:12, 1:25, 1:50, 1:75 and 1:100. Most of the work was carried out with a conjugate having a 1:25 molar ratio. In vitro photosensitization was tested using A549 (human lung carcinoma), A432 (human epidermoid carcinoma) and P815 (mastocytoma of DBA/2 mice) cell lines. Photosensitization of M1 (rhabdomyosarcoma of DBA/2 mice) tumors was tested in an in vivo/in vitro assay, in which tumor-bearing mice were injected intravenously with free or conjugated 3H-BPD and 3 h later light activation of tumor cells was carried out in vitro. Biodistribution studies were carried out using M1 tumor-bearing DBA/2 mice and 3H-BPD either free or conjugated to M-PVA. The results of these studies showed that the conjugation of BPD to M-PVA resulted in the formation of a macromolecular photosensitizer that retained full photosensitizing activity of the photosensitizer molecules and at the same time gained new characteristics, advantageous for photodynamic treatment, especially in vivo. In vitro M-PVA-BPD conjugates were at least as efficient in photosensitization of tumor cells as an equivalent number of free BPD molecules, both in the presence and in the absence of serum. Although the biodistribution was in general comparable to free BPD, the conjugate (1:25) reached slightly higher levels in the blood, kidney, lung and spleen, and lower levels in the liver, brain, skin and muscle in comparison with free BPD.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

["Mother" and "father" in psychoanalytic case vignettes. On some latent rules in the discourse of psychoanalysis].

Proceeding from the conviction that there is a collective gender-specific unconscious within the community of psychoanalysts which determines latent rules operative in psychoanalytic discourse, the authors have conducted a research project extending over a number of years and systematically examining case descriptions in psychoanalytic journals to see to what extent those latent gender-specific rules are in fact observed in such publications. The project examines the way in which male and female analysts employ the terms "mother" and "father" in these publications and also the frequency and connotations of concepts related to "mother" and "father". Significant differences between male and female analysts become apparent, substantiating the assumption of a collective gender-specific unconscious. The authors conclude that this unconscious finds its way into psychoanalytic therapy, leading to unconscious counter-transference reactions that are acted out rather than worked on.

Countertransference↗
PubMed1993

[Epidermal cysts and folliculitis caused by cyclosporin A].

A 66-year-old man was treated with cyclosporin A (Sandimmun) after a kidney transplant and developed numerous epidermal cysts, comedones and folliculitis in the 2nd year of the immunosuppressive therapy. The eruptions were more marked on the back and in the temporal and retroauricular regions of the face. Histological examination of a cystic tumour revealed a follicular cyst of the acro-infundibular type. While hypertrichosis and gingival hyperplasia are now well known as side effects of cyclosporin A, cystic and acneiform skin lesions must also be attributed to this drug.

Acne Vulgaris↗
PubMed1993

[Technical, material and biomechanical requirements for alloplastic replacement of the anterior cruciate ligament surgical technic].

Chronically instable knee-joints progressively draw to an arthrosis as a result of the irregular kinematic. Different operative techniques to replace the anterior cruciate ligament using exclusively autologous, homologous or heterologous grafts in all cases of chronic instabilities, but the primary sole suture of acute ACL injuries, too, didn't show long-term stable results in many cases. Recurrent ruptures were found first of all at the intraarticular edge of the femoral tunnel caused by permanent abrasions of the replacement. The reason why is the large angle of the ACL and each replacement respectively under motion. The question of what tissue could or should be used for renewed autogenous reconstructions in case of re-instabilities and after using bone-tendon-bone-mid-third patellar-tendon-grafts isn't yet been discussed to the end. Because of the fact that there is no isometric behaviour of the complete ACL but of a few fibres only depending on the position of the knee the complete reconstruction of the ACL is absolutely impossible, but only a partial substitute. The anatomically limited intraarticular joint-space (notch) confines the replacements in their dimension and endangers voluminous reconstructions by an impending impingement especially as a result of the immediately postoperative swelling of the transplants. The use of the mid-third-patellar-tendon-graft destroys a lot of proprioceptors and causes a partly loss of the neuromuscular balance previously impaired by the loss of the ACL including its receptors. In addition to this the still existing proprioceptors of the ligamentous stumps can be definitively destroyed by big tunnels. Each autologous graft passes a long-term transformation and at best achieves to 50% of the maximum stress capacity of an original ACL after two years. Resulting from these reasons synthetic and unlimited-ly available ligaments presented themselves to be used for ACL replacements. The Trevira-ligament of polyethylenetherephthalat (= TRE-VIRA HOCHFEST 730R) seems to be best qualified therefore at the present. It meets the material and technical requirements and makes allowance for all biomechanical knowledge. A modified over-the-top technique by arthroscopy or mini-arthrotomy (minimized operative trauma) enables the preservation of still existing ligamentous tissue on the one hand and guarantees the immediate postoperative functional therapy on the other hand. A recurrent instability independent of cause doesn't bring about a worse starting position for the following renewed stabilization and enables corrective operative techniques including the substitute of a ruptured synthetic ligament if required.

Anterior Cruciate Ligament↗
PubMed1993

[Sonography of pregnancy in sheep. II. Accuracy of transrectal and transcutaneous pregnancy diagnosis].

Pregnancy was diagnosed by transcutaneous ultrasonography in 327 ewes of 2 flocks. In addition transrectal sonography was performed in 93 of these ewes. Two hundred and thirty six ewes were pregnant and 88 animals were non-pregnant. Criteria to assess the accuracy of transrectal and transcutaneous sonography were overall accuracy (correct diagnoses/all diagnoses), sensitivity (correct diagnoses "pregnant"/all pregnant animals), specificity (correct diagnoses "non-pregnant"/all non-pregnant animals), predictive value of positive diagnoses (correct diagnoses "pregnant"/all diagnoses "pregnant"), predictive value of negative diagnoses (correct diagnoses "non-pregnant"/all diagnoses "non-pregnant"). Accuracy, sensitivity, specificity, predictive value of positive diagnosis and predictive value of negative diagnosis were 95%, 95%, 91%, 99% and 71% with the transcutaneous sonography resp. 94%, 95%, 93%, 97% and 86% with the transrectal sonography. Accuracy of the transrectal examination was superior (100%; 26/26) to the transcutaneous approach (89%; 39/44) in early pregnancy (Day 22 to 90). Transcutaneous sonography was more appropriate during the last part of pregnancy. The results demonstrate that both methods allow reliable pregnancy diagnosis in sheep under farm conditions. Ultrasonic pregnancy diagnosis is of economical value, if pregnancy rate of herds is below 90% and the diagnostic accuracy reaches at least 95%.

Animals↗
PubMed1993

[Homeopathy in veterinary medicine and its pharmacologic/toxicologic and drug regulatory evaluation].

This review gives a summary of the definitions, delimitations and principles of homeopathy and its potential mechanisms of action, which is followed by an overview and critical evaluation of the most important homeopathic drugs registered for treatment of animals. It is shown that several of the marketed homeopathic drugs for treatment of animals violate current drug laws and represent a risk for both the animals and the consumer of food produced from animals. Based on these potential risks of homeopathic treatments, new EC regulations were recently published, which will markedly affect (and hopefully improve) the current situation of veterinary homeopathic drugs.

Animals↗
PubMed1993

Efficacy of benzoporphyrin derivative, a photosensitizer, in selective destruction of leukemia cells using a murine tumor model.

The ability of a photosensitizer, benzoporphyrin derivative monoacid ring A (BPD), and light to selectively kill leukemic cells in comparison to normal hemopoietic progenitors was investigated using a murine model, the L1210 tumor of DBA/2 mice. In vitro experiments indicated that treatment of cells with BPD and light effected a 5 to 6 log reduction of clonogenic L1210 cells under conditions which caused less than a 1 log reduction of committed myeloid progenitors, determined by colony-forming cells. This apparent therapeutic window was tested in vivo using lethally irradiated DBA/2 mice hematopoietically reconstituted with 10(6) syngeneic donor splenocytes or 5 x 10(5) bone marrow cells mixed with L1210 cells and treated with BPD and light. Reconstitution with 10(6) splenocytes resulted in successful engraftment of approximately 50% of recipients, indicating that these conditions provided limiting numbers of essential stem cells. The minimum tumor-eliciting dose was determined to be between 10(1) and 10(2) L1210 cells. Experiments in which 10(6) splenocytes were mixed with 10(6) L1210 cells and treated with BPD and light demonstrated that at 100 ng/mL of BPD and a specified light dose (5.4 joules [J]/cm2), 50% of recipients underwent successful engraftment and did not develop leukemic ascites. Animals that died under this regimen died from failure to engraft rather than from tumor burden. These results establish that this approach can effectively lower tumor burden by 4 logs with virtually no loss of essential hemopoietic progenitors. Similar results were obtained when animals received bone marrow rather than splenocytes.

Animals↗
PubMed1992

Multidomain binding of transforming growth factor alpha to the epidermal growth factor receptor.

Solubilized epidermal growth factor receptor (EGF-R) has been used in an extension of the Geysen epitope mapping protocol in order to provide additional insight into the amino acid residues in human transforming growth factor alpha (hTGF alpha) which are critical to recognition and binding. Overlapping heptapeptides which encompassed the 50 amino acid primary sequence of hTGF alpha were synthesized on a polyethylene solid phase, and the amount of detergent-solubilized EGF-R bound to each peptide was measured using ELISA. EGF-R appeared to bind reproducibly to four heptapeptides cognate to sequences in both the N- and C-domains of hTGF alpha (residues 22-28, 28-34, 36-42, and 44-50). Visualization of these four regions on three-dimensional solution phase structures of hTGF alpha, derived from 1H NMR measurements [Kline, T.-P., Brown, F.K., Brown, S.C., Jeffs, P.W., Kopple, K.D., & Mueller, L. (1990) Biochemistry 29, 7805-7813], indicated that the peptide segments are located on a single face of the protein and suggested the presence of a potential receptor binding cavity. If peptide segments within both the N- and C-domains of hTGF alpha are involved in binding to EGF-R, then this has direct consequences for possible molecular mechanisms by which receptor activation might take place. For example, the observed conformational flexibility in the six NMR-derived hTGF alpha structures due to variations in the main-chain torsion angles of Val-33, in combination with the involvement of residues from both domains in the proposed binding cavity, may imply that receptor activation results from interdomain reorientation in the protein ligand.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Increase of serotonin in plasma during onset of halothane-induced malignant hyperthermia in pigs.

The levels of serotonin (5-HT) were determined in platelet-free and platelet-rich plasma before and during the onset of halothane-induced malignant hyperthermia (MH) in genetically MH-susceptible pigs. During MH onset, the free (i.e. physiologically active) levels of 5-HT in plasma rose concomitantly with the increases in muscle tone, body temperature, venous pCO2 and plasma lactate. Since pharmacological stimulation of 5-HT2 receptors has recently been shown to trigger MH in susceptible pigs, the finding of increased 5-HT plasma levels during onset of halothane-induced MH may indicate that 5-HT is involved in the mechanisms by which volatile anesthetics trigger this myopathic syndrome.

Animals↗
PubMed1992

Comparison of replicative and non-replicative chromatin assembly pathways in HeLa cell extracts.

It has been reported that chromatin assembly in mammalian cell extracts depends exclusively or preferentially on ongoing DNA replication (Stillman, B. (1986) Cell 45, 555-565). More recently, this view has been challenged demonstrating that, in the same extracts, chromatin can also be formed efficiently in the absence of DNA replication (Gruss et al. (1990) EMBO J. 9, 2911-2922). The experiments, described in this communication, were performed to resolve this apparent contradiction. We found that there are at least two distinct in vitro pathways for chromatin assembly in HeLa cell extracts. The replicative pathway requires a nuclear protein, most likely identical with the chromatin assembly factor, described by Stillman (1986, Cell 45, 555-565), and the free soluble histones present in the cytosol of S phase cells. In contrast, a non-replicative pathway was identified that depends on isolated nuclear histones. As one component of the non-replicative assembly pathway we identified a cytosolic factor that was purified to apparent homogeneity and shown to be an acidic 50 kDa polypeptide. The isolated cytosolic 50 kDa protein efficiently promoted nucleosome assembly as demonstrated by one- and two-dimensional gel electrophoresis of in vitro packaged plasmid DNA.

Antigens, Polyomavirus Transforming↗