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Biomedical subjects

A Friedrich

Publications and source records attributed to A Friedrich.

At least 55 records · Page 3Linked to original sources
PubMed1992

Use of enzyme immunoassay and reverse-phase high-performance liquid chromatography to detect and confirm identity of dexamethasone in equine blood.

An enzyme immunoassay (EIA) was developed for detection of dexamethasone in equine blood. Dexamethasone 21-hemisuccinate-bovine serum albumin was used for immunization of rabbits, and prednisolone 21-hemisuccinate-horseradish peroxidase was used as enzyme conjugate. The assay had sensitivity in the low-picogram range (detection limit, 0.3 pg/well, 50% inhibition of binding at 4.5 +/- 0.7 pg/well). Apart from cortisol, which was recognized by the antiserum at concentration > 8.5 ng/ml, the dexamethasone antiserum failed to interfere with endogenous steroids, but cross-reacted with triamcinolone, flumethasone, and betamethasone. Thus, the antiserum was used to perform simultaneous screening for these synthetic glucocorticoids and to confirm their identity by combining reverse-phase high-performance liquid chromatography (RP-HPLC) and EIA. The immunoreactivity obtained by direct serum measurements was characterized by means of 2 independent RP-HPLC systems. Serum extracts were submitted to RP-HPLC systems I and II, and the fractions were tested by EIA. Immunoreactive peaks were identified by comparing their retention time with that of the standard glucocorticoids used for calibration. Coinjection of an internal standard (methylprednisolone) in RP-HPLC system II yielded reproducible relative retention times. The effectiveness of the test system was evaluated, using blood from a horse treated with commonly used veterinary preparations of dexamethasone. Administration of the free alcohol of dexamethasone and of dexamethasone 21-trioxaundecanoate, both given IV, was detected, and the identity of each was confirmed for up to 48 hours. Intramuscular administration of dexamethasone 21-isonicotinate was continued for at least 14 days after injection of a therapeutic dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Development of the rabbit retina: II. Müller cells.

Müller (glial) cells of the rabbit retina were stained with antibodies against the intermediate filament protein vimentin in retinal wholemounts from various developmental stages. Both the density of stained profiles and the mean diameter of these profiles were measured, with the microscope focus in the inner plexiform layer of the retinae. Within this retinal layer, every Müller cell possesses one stout vitread process; thus counts of the stained profiles allow an estimation of their number. After postnatal day (P) 9, the total number of stained cells was slightly above 4 million per retina; for the adult rabbit retina, this agrees well with earlier data obtained by our group based on another method, as well as with published data from other groups. We suggest that after P 9, only Müller cells are stained, and this population is numerically stable. In contrast, neonatal retinae contained significantly more stained profiles. This indicates that either the total number of Müller cells is reduced by "physiological cell death" or that additional cells are stained neonatally. We discuss why we favour the second possibility. After P 9, two peculiarities occur in the Müller cell population: (1) their density decreases gradually, to a greater extent in the retinal periphery than in the center (i.e., in the "visual streak"), and (2) Müller cell diameters increase, again more in the periphery than in the center. We argue that differential retinal expansion leads to dispersion of the pre-existing cell population and allows for widening of the Müller cell processes. We conclude that Müller cells can be used postnatally in the rabbit retina as "landmarks" of expansion.

Aging↗
PubMed1991

Development of the rabbit retina. I. Size of eye and retina, and postnatal cell proliferation.

Measures of rabbit eyes and retinal wholemounts were used to evaluate the development of retinal area and shape. The retina is shown to have a horizontal axis about a third longer than the vertical axis just before birth, and to adopt an almost symmetrical shape during postnatal development to adulthood. In general, retinal thickness is shown to decrease after birth, but differently in particular retinal regions: the reduction is marked in the periphery, and less pronounced in the visual streak. As an exception, the myelinated region--after it becomes really myelinated, from 9 days p.p.--even increases in thickness. In all regions of the retina, the absolute and relative thickness of the nuclear layers decreases, whereas the relative thickness of plexiform and fibrous layers increases. Proliferation of cells within the rabbit retina was studied during the first three postnatal weeks. 3H-thymidine incorporation was used to demonstrate DNA synthesis autoradiographically in histological sections as well as in enzymatically isolated retinal cells. A first proliferation phase occurs in the neuroblastic cell layer and ceases shortly after birth in the retinal center, but lasts for about one week in the retinal periphery. We found, however, a few 3H-thymidine-labeled cells as late as in the third postnatal week. These late-labeled cells were found within the nerve fiber layer and in the inner plexiform layer. The latter cells were shown to express antigens detected by antibodies directed to the intermediate-sized filament protein vimentin, which are known to label Müller cells and neuroepithelial stem cells. This was confirmed in our preparation of enzymatically isolated cells; all cells with autoradiographically labeled nuclei revealed a characteristic elongated morphology typical for Müller radial glia (and also for early neuroepithelial stem cells). 3H-thymidine-labeled cells in the nerve fiber layer were most probably astrocytic. In analogy to the brain, we conclude that the mammalian retina undergoes a series of proliferation phases: first an early phase producing both neurons and glial cells, and then a late phase producing glial cells, e.g., in the nerve fiber layer. Most probably, the late phase within the inner nuclear layer is glial as well, i.e., consists of dividing Müller cells; it cannot be excluded, however, that there may remain some mitotically active stem cells.

Animals↗
PubMed1990

Detection of latent thymidine kinase-deficient herpes simplex virus in trigeminal ganglia of mice using the polymerase chain reaction.

Latency of thymidine kinase-negative mutants of herpes simplex virus (TK- HSV) could not be detected by reactivating the virus from the ganglia of infected mice. Because Southern blot hybridization was not sensitive enough to detect viral DNA, positive results obtained by dot blot hybridization were ascertained by the highly specific and sensitive polymerase chain reaction (PCR), which detected both latent TK- HSV type 1 and 2 DNA from the trigeminal ganglia of infected mice.

Animals↗
PubMed1990

[Modulation of granulocyte phagocytosis].

Non-specific complications are encountered relatively often in patients with below normal granulocytic phagocytosis rates. We tested vitamin C, transfer factor, gamma-globulin, BCG, PPD, UV irradiation of the subject's blood (UVB) and hyaluronidase with the aim of stimulating granulocytic phagocytosis with rice starch in autologous serum. In our experiments, only the addition of hyaluronidase caused any increase in phagocytotic activity. The in vitro experiments with hyaluronidase yielded promising results and will be followed up since they may be relevant to practical questions.

Ascorbic Acid↗
PubMed1990

[Detection of dexamethasone in horses].

Due to their marked antiinflammatory effect, synthetic corticosteroids are used to mask illness, especially lameness in horses. The detection of these drugs in equine body fluids requires accurate methods, particularly where misuse of corticosteroids is suspected. Gas chromatography/mass spectrometry (GC/MS) is well established as a reliable technique for the identification of drugs in biological fluids. Using GC/MS, we determined dexamethasone levels in horse urine and serum after intravenous application of a therapeutic dose. Dexamethasone was detectable, in serum for up to six hours, and in urine for up to 32 hours, after its administration. These findings indicate that serum measurements are unreliable for the detection of corticosteroid abuse, and demonstrate urine to be a more suitable body fluid for investigation. Nevertheless, it should be emphasized that, regardless of the technique employed, the clinical effects of dexamethasone last longer than 32 hours; thus, failure to detect dexamethasone does not disprove corticosteroid abuse.

Animals↗
PubMed1990

[Drug residues in food fish].

The present paper reviews different possibilities of pharmacolegal residues in fish. Sometimes the treatment of fish with registered drugs in therapeutical dosage is provable in spite of keeping the withdrawal time. To that experiences of the persistence and values of Chloramphenicol, Chlortetracycline and Furazolidone proved after therapeutical treatment in fish correlated to the water temperature are compared with results of experiments documented in literature. Investigations on the residues of Enrofloxacin after application of different doses to rainbow trout were carried out. Sometimes the proof of drug residues in fish can be done without an advanced treatment. The recontamination of fish with drugs or their metabolites in environment is discussed as a possibility for drug residues. The carry-over-effect of drug during the animal food production can be also the reason for residues in fish. Experiments with Chloramphenicol contaminated feed in rainbow trout show residues in muscle of fish higher than 10 ppb during the feeding period. Finally the results of residues different drug used in fish--given in literature--are collected in two tables.

Animals↗
PubMed1989

Comparison of different methods for detecting human immune deficiency virus in human immunodeficiency virus-seropositive hemophiliacs.

Since the detection of antibodies against the human immune deficiency virus (HIV) does not definitely prove HIV infection in hemophiliacs, virus detection was attempted by virus isolation from the peripheral blood monocytes (PBL), by demonstration of p24 antigen and decline of p24 antibody, and by detection of viral DNA by the polymerase chain reaction (PCR). Virus isolation was optimized by immediate coculture of PBL and by replacement of the reverse transcriptase test by the p24 antigen test, whereas the elimination of CD8+ lymphocytes proved to be unnecessary. Virus detection was dependent on the clinical stage of the illness. Virus isolation in 70 of 211 patients (33%) was more sensitive than detection of p24 antigen or decline of p24 antibody. PCR was performed in 25 patients and indicated infection in all of 15 isolation-positive cases and in 6 of 10 patients from whom virus was not isolated. Changes from negative to positive virus culture and from a weakly fusiogenic to a highly fusiogenic isolate were often accompanied by a progression of the disease. The results suggest that reactivation of HIV occurs when immune deficiency has become manifest. Apparently virus isolation detects only the virus already reactivated in vivo, whereas the PCR may also detect latent virus.

Antibodies, Viral↗
PubMed1989

Immunoreactive atrial natriuretic peptide in the guinea pig spleen.

The presence of immunoreactive ANP precursor-like material in the guinea pig spleen is suggested. This is based on the following experimental evidence: An acidic extract of guinea pig spleen analysed by Sephadex G-50 gelfiltration contained 4.6 pmol/g wet tissue immunoreactive atrial natriuretic peptide (IR-ANP), coeluting with the 15 kDa synthetic ANP (2-126). Gelfiltrated IR-ANP material was further submitted to reverse phase high performance liquid chromatography and monitored by radioimmunoassay employing two antisera. One antiserum recognizes the C-terminal of ANP (1-126), the second is directed against the N-terminal sequence. Both antisera revealed material eluting with synthetic ANP (2-126). Furthermore, immunohistochemical analysis suggests this ANP-like material to be localized mainly at the periphery of the white pulp of the spleen. These findings link ANP with the immune system.

Animals↗
PubMed1988

Immunological mechanisms giving rise to latency of herpes simplex virus in the spinal ganglia of the mouse.

In the model of genital herpes simplex virus (HSV)-infection of mice, early latency could be induced by passive immunization with HSV-specific antibodies and, to a lesser degree, by adoptive transfer of immune lymphocytes prepared from spleen and draining lymph nodes of genitally infected syngeneic mice. Conversely, spontaneously occurring latency was inhibited by treatment of the animals with cyclophosphamide (Cph) and, to a lesser degree, with cyclosporin A (CyA). Whereas the effect of CyA could be compensated by passively administered HSV-specific antibodies, that of Cph could not. Apparently specific antibodies cooperate with a non-specific proliferating cell type, probably macrophages and/or NK-cells, as could be demonstrated by significantly reduced antibody effect in silica-treated mice. Moreover, F(ab)2 fragments, in contrast to complete antibody molecules, were inactive. HSV-specific antibodies and also immune lymphocytes had little effect on virus production in the mucous membranes, immune lymphocytes being at least as active as antibodies. It is therefore not probable that latency is induced by attenuation of the peripheral disease. It can rather be concluded that the neuron itself is the target for the action of specific antibodies, cooperating in turn with macrophages and/or NK cells.

Animals↗
PubMed1988

[Clinical and prognostic aspects of multiple cancers].

The anamnestic data, course and prognosis for 76 patients with multiple carcinomas were statistically analyzed in a retrospective study undertaken jointly with the oncological working group. The importance of multidisciplinary care for this group of patients over a period exceeding five years must be emphasized. If the general status of a patient deteriorates, the doctor should always consider the possibility of a second or third carcinoma.

Adult↗
PubMed1986

[Oncologic after-care of patients with prostate cancer].

The aim of the examinations is the proof of the clinical value of the granulocyte phagocytosis test in the after-care of the palliatively treated patients with a carcinoma of the prostate. On the basis of the analysis of the own patient and the observation of the course the routine control of the granulocyte phagocytosis is recommended, since unspecific complication are recognized earlier and thus may be treated better.

Adenocarcinoma↗
PubMed1986

[Significance of preoperative prognosis].

The granulocyte phagocytosis test, Karnofsky index, and ASA standard were used in the context of 287 patients for general surgery, for the purpose of retrospective elucidation of the relationship between presurgical prognostication and postsurgical complications. Sensitivity, specificity, and "predictive values" were calculated. The highest information potential in terms of prognostication was recorded from objectively measurable granulocyte phagocytosis. Presurgical prognostication was found to be of clinical relevance only to surgical problem patients.

Granulocytes↗
PubMed1986

[Simultaneous investigations on granulocyte phagocytosis using rice starch and on granulocyte migration--a study in the preoperative definition of the defense situation of the organism].

Information which is more extensive than the unspecific value of the granulocytophagocytosis could not be found out by the simultaneous investigations of the granulocytophagocytosis and the granulocytomigration. The application of AHLG and tumor-associated antigens in the migration test system did not show specific results for the oncology. The granulocytomigration in a home-made modified Boyden chamber did not show any sexual distinctions. No statistical reliable relations could be found out between the rate of migration and ingestion of the granulocytes. The granulocytophagocytosis does not obtain a higher value for practice by the simultaneous definition of the migration.

Chemotaxis, Leukocyte↗
PubMed1986

[A foreign body in the urinary bladder].

A case concerning the problems of the foreign bodies of the urinary bladder is demonstrated. The 6-year indwelling stay of the foreign body without consultation of a physician and the oral intake at first reported, which was later on revised, are unusual.

Adolescent↗