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Biomedical subjects

L Richter

Publications and source records attributed to L Richter.

At least 55 records · Page 3Linked to original sources
PubMed1996

Increased biliary secretion of cysteinyl-leukotrienes in human bile duct obstruction.

BACKGROUND/AIMS: The pathophysiological role of leukotrienes in liver disease is not well understood. Redistribution or enhanced formation in cholestatic states may result in increased hepatic concentrations that are expected to contribute to liver injury. To disclose the potential role of cysteinyl-leukotrienes in chronic liver diseases, we studied biliary and urinary secretion in the model situation of relief of bile duct obstruction. METHODS: Concentrations of cysteinyl-leukotrienes were determined in bile and urine of patients with extrahepatic biliary obstruction in the course of therapeutic decompression by endoscopic or transhepatic techniques. Leukotrienes were measured by radioimmunoassay after HPLC separation. Concentrations of bile acids in bile and serum were measured for comparison. RESULTS: Bile collected 2 h after decompression contained high concentrations of leukotrienes (57.5 +/- 22 microM). Biliary secretion decreased over 24 h reaching equilibrium values after 48-72 h (2.8 +/- 1.7 mM and 6.4 +/- 6.6 microM, respectively). Total bile acid concentration in serum followed a similar time course. In contrast, biliary bile acid concentration showed high interindividual variations. Bile contained all leukotriene C4, D4, E4 and NAc-LTE4, but LTC4 was predominant. Urinary leukotriene secretion in cholestasis (199.7 pmol/mmol creatinine) was less than 7% of maximal biliary secretion. It further decreased to 116.4 pmol/mmol creatinine within 72 h. Urine also contained all species of cysteinyl-leukotrienes, but the relative amounts of LTE4 and NAc-LTE4 were higher than in bile. CONCLUSIONS: Formation of cysteinyl-leukotrienes is increased in obstructive jaundice resulting in increased urinary excretion before and both biliary and urinary excretion after relief of the obstruction. Predominance of LTC4 suggests that the secreted leukotrienes are newly formed. Increased synthesis and retention of hepatic cysteinyl-leukotrienes may contribute to hepatic and extrahepatic consequences of cholestasis.

Aged↗
PubMed1996

RNA-dependent association of the Drosophila maleless protein with the male X chromosome.

BACKGROUND: Dosage compensation results in equivalent X-linked gene expression in males (XY) and females (XX). In Drosophila, both X chromosomes are active in females, and the single male X must double its transcriptional activity to allow male development. Four proteins (encoded by the male-specific lethal genes) are required for dosage compensation and associate with the X chromosome in males but not in females. RESULTS: In this report, we focus on the maleless (MLE) protein. The MLE protein sequence contains motifs common to members of a family of RNA-dependent ATPases. We have found that association of MLE with the male X chromosome is RNase sensitive, and that mutations in the ATPase motifs affect MLE function. Overexpression of MLE or its carboxyl terminus, which includes glycine-rich repeats, reveals an RNase-sensitive affinity for all chromosome arms. CONCLUSIONS: Our results suggest that nascent transcripts or a hypothetical RNA component of chromatin play a critical role in the biochemical mechanism of dosage compensation. The potential relationship between interaction with RNA and transcriptional control of the X chromosome suggests that the mechanism of dosage compensation is distinct from classical models for transcriptional activation.

Adenosine Triphosphatases↗
PubMed1996

[Materials for the training of hearing based on phonetic-acoustic features of the Polish language].

Even a careful fitting of hearing aid cannot always guarantee full recompensation for lost hearing. Although speech is significantly strengthened by the hearing aid, the received signals sound slightly differently. To take full advantage of hearing aid capacity and to understand speech better, it is necessary to carry out exercises within the hearing training. The aim of the exercises is to acquire perceptive differences appearing between particular speech sounds. Each exercise deals with particular phonetic distinctive feature differentiating the speech sounds of the Polish language. Language substance comprises the so-called minimal pairs: pairs of words which differ only by one speech sound e.g. park, kark. Preservation of identical phonetic structure within remaining parts of words allows for the exposure of sound differences referring to selected speech sounds. First exercises with children who lost hearing in the prelingual period should be carried out for a period between a few weeks to a few month with the cooperation and under a supervision of a specialist (logopedics or surdopedagogics).

Hearing↗
PubMed1994

Sex-specific regulation of the male-specific lethal-1 dosage compensation gene in Drosophila.

Dosage compensation in Drosophila occurs by a twofold increase in transcription per copy of X-linked genes in males (XY) compared with females (XX). msl-1 is one of four genes that are essential for dosage compensation in males, and MSL-1 protein is associated specifically with the male X chromosome. To explore the basis for the sex specificity of dosage compensation, we examined MSL-1 expression in males, females, and dosage compensation mutants. MSL-1 protein levels are negatively regulated by Sxl in females, resulting in male-specific expression of MSL-1. In addition, msl-2 is required for translation and/or stability of MSL-1 in males. Furthermore, the wild-type pattern of MSL-1 localization to the X chromosome is dependent on mle and msl-3 function, although a subset of sites are stained with MSL-1 antibodies in these mutants. Collectively, these data provide the first evidence for an order of msl gene function and suggest that male-specific expression of MSL-1 plays a key role in the sex specificity of dosage compensation.

Animals↗
PubMed1994

[New articulation lists for speech audiometry. Part I].

Ten articulation lists for speech intelligibility testing and evaluation of hearing impairment type have been constructed. Each list contains 24 from among the most frequent monosyllabic Polish nouns. The lists are balanced phonemically, semantically, acoustically and structurally.

Audiometry, Speech↗
PubMed1994

[New articulation lists for speech audiometry. Part II].

Ten articulation lists for speech intelligibility testing and evaluation of hearing impairment type have been constructed. Each list contains 24 from among the most frequent monosyllabic Polish nouns. The lists are balanced phonemically, semantically, acoustically and structurally.

Audiometry, Speech↗
PubMed1993

Depressive symptomatology in hospitalised children.

This study was undertaken to determine the extent and nature of depressive symptoms exhibited by black South African children during hospitalisation for orthopaedic procedures. Social factors associated with the risk for depression, in response to hospitalisation, were also examined. Pre- and post-test assessments were conducted on a sample of 30 children, aged between 6 and 12 years. The assessment entailed a structured interview, together with the following psychometric instruments: A Global Mood Scale, a Depressive Symptoms Checklist, a Hospital Fears Rating Scale and a Self Report Depression Rating Scale. A large proportion of the children were rated by ward sisters as showing high levels of depressive symptomatology two weeks after admission to hospital. As expected, discrepancies were found between adult and child self-ratings of depression. The results of this study indicate that hospitalisation for orthopaedic child patients is associated with the development of depressive symptomatology. It is suggested that emphasis be placed on the development of supportive programmes and procedures aimed at maximising children's coping responses to hospitalisation, particularly for children who find themselves isolated from their communities and families, as a result of both centralised health services and poor socio-economic conditions.

Adaptation, Psychological↗
PubMed1992

[The development of the yolk sac in ruminants (sheep and cattle)].

Yolk sac development was investigated in 69 ovine and 10 bovine embryos from the blastocyst stage to the 7th week of gestation. Light and electron microscopical findings are reported. The yolk sac in sheep and cattle is composed of an enlarged sac-like portion lying below the embryo and two ends which follow the elongated course of the trophoblast. In sheep, an open connection exists between the intestines and the yolk sac up to a crown-rump length (CRL) of 9 mm. It is closed by 12 mm CRL. The wall of the yolk sac is especially well vascularized in the enlarged, sac-like portion. Primary erythropoiesis occurs within the blood capillaries. In the blastocyst, the yolk sac entoderm is made up of elongated, flat cells. It becomes cuboidal in the 3 mm embryo (ovine) and later columnar. The up to 20 microns tall cells stain darkly and contain numerous light-colored vesicles. At 4.5 mm CRL light cells appear between the dark ones. Both cells are rich in rough endoplasmic reticulum (rER). The increased staining of the darker cells is due to an osmophilic cytoplasm and numerous, often parallel lamella of rER. The rER of the light cells is enlarged to irregularly-shaped cisternae, which nearly fill the entire cytoplasm and give them a rounded appearance. The dark cells contain polygonal nuclei, whereas those in the light cells are round with one or two nucleoli. The oval mitochondria have only a few peripheral cristae. Golgi fields are not very common. Cells of the entoderm are connected to one another over zonulae occludentes. They possess microvilli on the luminal surface and are supported by a basement membrane. From 5 mm CRL onwards (ovine), the yolk sac entoderm folds itself between the capillaries, thereby becoming stratified. The intercellular space between the cells expands as projections between neighboring cells interlock. Canaliculi arise between adjacent epithelia. The wall of the yolk sac thickens as a result of this infolding and the densely packed capillaries. Infoldings are especially predominant in the sac-like portion of the yolk sac, and only suggested in the ends. Involution of the yolk sac begins in the peripheral end segments and proceeds centripetally. Numerous glycogen particles appear in the yolk sac entoderm cells of the ovine fetus at a CRL of 36 mm, and by a CRL of 42 mm, the sac-like portion has also begun to show signs of degeneration. Mesenchyme is very sparse within the wall of the yolk sac throughout the entire period of development.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Characterization of the memory gene dunce of Drosophila melanogaster.

The dunce (dnc) gene of Drosophila melanogaster encodes cAMP phosphodiesterase (PDEase) and is required for learning/memory and female fertility. The gene is structurally complex, demonstrated in part by Northern blotting experiments which detected multiple RNAs ranging in size from 4.2 to 9.6 kb (1 kb = 10(3) bases or base-pairs). To characterize these RNAs and to understand their sequence heterogeneity, we isolated and analyzed 29 new and independent cDNA clones representing the dnc RNAs. Restriction mapping, hybridization analysis and sequence determination of these cDNA clones and the corresponding genomic exons resolved these into six different classes. Exons defined by the cDNA clones are distributed over more than 148 kb of genomic DNA, with some exons being used alternatively among the RNAs. The RNAs are transcribed from at least three initiation sites: two of these were mapped by parallel S1-nuclease and primer extension experiments. In addition, some of the heterogeneity is generated by using varying lengths of a 3'-untranslated trailer sequence. Altogether, the results indicate that the size and sequence heterogeneity of dnc transcripts results from transcription initiation at multiple sites, alternative splicing, and processes which generate different 3' ends. The existence of multiple protein products is suggested by the alternative use of exons which code for portions of the open reading frame. The protein variation potentially includes N-terminal differences coded for by transcript-specific 5' exons and internal differences arising from the optional inclusion of a 39 base-pair exon and from the alternative use of two 3' splice sites separated by six base-pairs. Expression of a cDNA clone in yeast containing a large portion of the open reading frame produced cAMP PDEase activity identical in properties to the Drosophila enzyme affected by the dnc mutation. The results suggest that the remarkable structural complexity of dnc may reflect an intricate control of the spatial and/or temporal expression of various isoforms of cAMP PDEase.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1991

Birth to ten: child health in South Africa in the 1990s. Rationale and methods of a birth cohort study.

Birth to Ten is a longitudinal birth cohort study which began in April 1990 in the Johannesburg/Soweto area of Transvaal, South Africa. In this paper, the reason for the initiation of the study and its location in the current sociopolitical context is discussed. The health status of South Africa children in terms of infant mortality, morbidity (notifiable diseases) and nutritional status is described and mention is made of measures of psychological health and the importance of environmental pollution on health. The existing health service infrastructure in the study area is described and the fragmentation of health services between races, between preventive and curative services and on a geographical basis is highlighted. The study objectives, design, population, inclusion and exclusion criteria, methods of measurement and logistics are described.

Child↗
PubMed1990

Plasma cells in multiple myeloma express a natural killer cell-associated antigen: CD56 (NKH-1; Leu-19).

Bone marrow samples from 55 patients with multiple myeloma (MM) and 23 patients with monoclonal gammopathy of undertermined significance (MGUS) were evaluated with a broad panel of monoclonal antibodies. Plasma cells from 78% (43/55) of patients with MM strongly expressed the natural killer cell antigen CD56 (NKH-1, Leu-19). Of the 23 patients with MGUS, none showed strong CD56 reactivity, although three had weak reactivity in less than 20% of plasma cells. Myeloma cells expressing CD56 did not coexpress the CD57 or CD16 antigens. Patients with CD56-positive plasma cells had both indolent and aggressive disease. However, the 12 CD56-negative patients had predominantly aggressive disease with an unexpected preponderance of kappa Bence Jones only myeloma (5/10[50%] evaluable patients). Polyclonal plasma cells from non-neoplastic tissue sites (normal bone marrows, lymph nodes, tonsillar biopsies, and gut-mucosa biopsies) showed a near absence of CD56. We conclude that isolated, strong CD56 expression is common in MM, but not in MGUS or reactive plasma cells. The potential biologic importance of CD56 positivity in myeloma is reviewed.

ADP-ribosyl Cyclase↗
PubMed1990

Ultrasonographic anatomy of normal prostate gland: reconstruction by computer graphics.

Computer graphic reconstructions of the prostate were made in both the transverse (axial) and longitudinal (sagittal) planes at different levels on the basis of the normal anatomic model of McNeal. Additional images then were created to give a picture of what the ultrasonogram should look like at each level, and these were compared with actual ultrasonograms of the normal prostate. A precise yet simple terminology is suggested for prostate ultrasonographic descriptions.

Adult↗
PubMed1990

Optimization of immunocytochemical P-glycoprotein assessment in multidrug-resistant plasma cell myeloma using three antibodies.

Seeking to optimize the immunocytochemical assay of P-glycoprotein, a 170-kilodalton (P-170) molecule associated with multidrug resistance, we experimented with a variety of antibodies (JSB-1, C219, and MRK-16), fixation conditions, and titers using both human myeloma cell lines and clinical myeloma specimens. Under optimized conditions, using all three antibodies and the cell lines as standards and controls, the ICC method proved sensitive, specific, reliable, rapid, and within the realm of everyday hospital laboratory expertise. The 3 anti-P-glycoprotein antibodies revealed different reactivities with P-170. Both C219 and JSB1 were optimized by fixation in cold acetone. With MRK-16 optimal results were obtained on unfixed or formalin fixed specimens. Under optimal fixation and titering conditions, low level (DOX 4) detection was possible. Given that the three antibodies differ in reactivity and recognize different P-170 epitopes, it follows that using the antibodies in a small panel is a useful strategy in increasing the likelihood of detecting true P-glycoprotein expression by the immunocytochemical method. In dilution experiments, the immunocytochemical method was as sensitive as RNase protection assay and more sensitive than Western blot detection. Immunocytochemistry coupled to computer-assisted single-cell densitometry, showed a strong correlation (R = 0.98) between cellular P-170 density and in vitro resistance to doxorubicin. Multidrug-resistant specific probes for RNA expression and Western blot assays confirmed the specificity of P-170 expression in both cell lines and clinical samples. Thus, a small panel of antibodies, under optimized immunocytochemical conditions, appears to have potential as a rapid, sensitive, clinically useful assay for multidrug resistance in myeloma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1989

[The appearance of ovarian cysts in young sows after treatment with gonadotropin preparations for estrus induction].

In 72 (46%) of 155 gilts discarded for genetic reasons after performance testing and housed under fattening conditions no heat could have been detected during the first 30 days. The gilts were assigned alternatingly to a control group and four different treatments of delayed puberty. The induction of puberty was carried out by injections of 1000 iu PMSG, 400 iu HCG and 2 mg oestradiol benzoate, 400 iu PMSG and 200 iu HCG and 800 iu PMSG and 400 iu HCG. If there was no estrus gilts were slaughtered 12 days later for examination of the ovaries. Those coming into estrus were slaughtered 8 days after disappearance of estrus. Estrus could be induced in 69 to 94% of the gilts, whereas 40% of the untreated showed estrus signs. After treatment with PMSG and HCG in 40 and 87% of the gilts cysts were found whereas none of the untreated and 26 and 29% of those treated with PMSG und HCG + oestradiol benzoate revealed ovarian cysts. In addition, those gilts that had come into estrus during the first 30 days were given injections of either 1000 iu PMSG or 800 iu PMSG and 400 iu HCG. The injections were made either on the 5th, 10th or 15th day of cycle. In both latter groups significantly more gilts showed standing heat than after treatment at cycle day 5. The results of inspection of the ovaries at slaughter and steroid hormones could not be assigned to a defined stage of the physiological ovarian cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Immunohistochemical detection and quantitation of P-glycoprotein in multiple drug-resistant human myeloma cells: association with level of drug resistance and drug accumulation.

Using several multiple drug-resistant human myeloma cell lines as standards, we developed an immunohistochemical staining technique and means of quantitating P-glycoprotein in individual myeloma cells. The level of staining intensity for P-glycoprotein in individual myeloma cells was quantitated by measuring the average optical density of each cell with a microscopic computerized cell analysis system. Using this system, we observed that the level of P-glycoprotein for individual cells within a cell population of known drug sensitivity was very homogeneous (coefficient of variation less than or equal to 13%). Analysis of cell lines with gradually increasing levels of multidrug resistance (8226/S, 8226/Dox6 and 8226/Dox40) demonstrated a close association between the level of resistance to doxorubicin, defined by the mean lethal dose (D0) and the amount of P-glycoprotein on individual cells determined by the optical density (r = 0.82, P less than 0.0005). Intracellular doxorubicin (DOX) accumulation in the individual cell lines was inversely related to the level of drug resistance expressed as D0. P-glycoprotein was also detected in the marrow-derived myeloma cells of patients with drug refractory disease using immunohistochemical staining. The amount of P-glycoprotein in the cells of one patient was directly compared to the amount found in the simultaneously stained standard cell lines (8226/Dox6 and 8226/Dox40) by comparing the optical densities for individual cells. Using this immunohistochemical technique to detect and quantitate P-glycoprotein in patient myeloma cells and comparing it to standard multidrug resistant myeloma cell lines may be of value in determining the contribution of P-glycoprotein to clinical drug resistance in patients with multiple myeloma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1989

Myelomonocytic antigen positive multiple myeloma.

In a four year span, between 1983 and 1987, 215 bone marrow and cell culture samples from 125 myeloma patients were immunotyped and coexpression of myelomonocytic and plasma cell antigens occurred in 16 (13%). We employed both immunohistochemical and flow cytometry methods including coplots and double labelling. Three types of myeloma cases were found: (1) those with isolated myeloid antigen coexpression, usually Leu M1 or esterase (BE, CE) positive (11 cases); (2) those with multiple myeloid antigens (Leu M1, M3, M5, MY7, BE, CE) (four cases); and (3) one case beginning as 1 and ending as 2. Isolated myeloid antigen expression was generally associated with typical features of myeloma with survival close to the anticipated median (33 months), while multiple myeloid antigen expression was associated with more aggressive disease and shorter survival duration (median survival 16 months). The latter subgroup also had other poor prognostic factors including high labelling index and common acute lymphoblastic leukemia antigen (CALLA) positivity. Other features found overall were frequent abnormal karyotypes (seven of 12 abnormal) and coexpressed IgA (eight of 16); all IgA+ cases also coexpressed Leu M1. We conclude that there is an unusual and unexpected predilection for coexpression of myelomonocytic antigens in myeloma cells. The reasons are not immediately obvious. Whether the coexpression indicates that myeloma cells truly have latent multilineage potential or just aberrantly coexpress other hematopoietic antigens as a manifestation of malignancy remains to be explained. However, a cell line established from the bone marrow of one patient is a valuable scientific tool allowing detailed analysis of these questions.

Antigens, Differentiation, Myelomonocytic↗
PubMed1989

[Muscular burden in current work activities exemplified by cash register work sites].

21 cash register operators (aged 18 to 49 years) have been studied in an industrial study. The investigation included the measurement of heart rate, bioelectrical muscle activity of the right and left M. biceps brachii and M. deltoideus and muscular endurance at 50% MVC. There were significant relationships between the movement of the left arm and the heart rate and the load of articles and the heart rate. The results in bioelectrical activity showed that there were a muscular load in the right and left muscles and findings of muscular fatigue in frequency distribution and in muscular endurance.

Adolescent↗