Search PubMed⌕ Search

Biomedical subjects

M Dietrich

Publications and source records attributed to M Dietrich.

At least 109 records · Page 6Linked to original sources
PubMed1990

Release and effects of oxytocin on estradiol and progesterone secretion in porcine corpora lutea as measured by an in vivo microdialysis system.

Individual corpora lutea (CL) of Göttinger miniature pigs were implanted with an in vivo microdialysis system. This system functions like an artificial capillary, allowing diffusion of intraluteally secreted substances into the lumen of the dialysis system and administration of hormones into individual CL and simultaneous measurement of the response. After surgery the sows are fully awake and unrestrained. In the present study the in vivo release rates and secretion dynamics of progesterone (P) and oxytocin (OXT) were investigated. The dialysis system was implanted at day 2-4 of the estrous cycle, and dialysis experiments were performed throughout the next 3 days. Fractions were collected at 30 min intervals, and the concentrations of P and OXT were measured by RIA. Three major observations were made: Spontaneous intraluteal secretion of P and OXT occurred in a pulsatile manner. OXT secretion episodes in individual CL often coincide, indicating a simultaneous release from many CL of one ovary but also from the CL located in the contralateral ovary. OXT episodes also often coincide with P pulses; statistical evaluation revealed a significant correlation between P and OXT secretion. Intraluteal application of OXT stimulated luteal P and estradiol (E2) release in a dose-dependent manner. E2 added to the perfusates was also stimulatory to P release. The stimulation of P release by OXT could be antagonized by prior treatment of the CL with tamoxifen. We demonstrate for the first time in vivo the secretion of OXT from porcine CL. The microdialysis system enabled us to collect samples at the site of steroid and peptide release, i.e. within the intact luteal tissue. Our results suggest a stimulatory effect of OXT on P release from young and middle-aged CL and are in marked contrast to the previously demonstrated inhibitory effect of OXT on P release when luteal cells were cultured in vitro. A possible explanation for this apparent discrepancy is that OXT stimulates intraluteal release of E2, which is a powerful P releasing hormone, overcoming the direct inhibitory effect of OXT. This suggestion is substantiated by the observation that E2, when added to the perfusion medium, indeed stimulated P release.

Animals↗
PubMed1990

Lymphatic tissue changes in AIDS and other retrovirus infections: tools and insights.

Based on immunohistochemistry, in situ hybridization, and electron microscopy, lymphatic tissue changes in human immunodeficiency virus (HIV) and other retroviral infections represent different stages of a dynamic process progressing from hyperplasia to atrophy. The germinal centers (GC) function early as a virus reservoir in both HIV and feline leukemia virus infection, which also produces lymphadenopathy, severe immune impairment, and death from opportunistic infections. Core proteins of HIV can be detected on the surface of follicular dendritic cells, electron microscopy reveals cell-free HIV and virus replication in the same location, and in situ hybridization shows that the majority of cells with mRNA of HIV can be found in germinal centers (GC). Double immunohistochemical labeling of lymphocyte populations suggests that one of the most important events in HIV lymphadenitis with explosive follicular hyperplasia is the accumulation of CD8+CD45R0+ lymphocytes in the lymph nodes. Their clustering in the vicinity of the FDC network could play a key role in disintegration of GC and lymphocyte depletion as the disease progresses.

Acquired Immunodeficiency Syndrome↗
PubMed1990

[Therapy of HIV associated mild and moderately severe Pneumocystis carinii pneumonia with 600 mg/die pentamidine aerosol. Results of a multicenter study].

In 22 HIV positive patients a mild to moderate pneumocystis carinii pneumonia was treated by daily inhalation for 21 days of 600 mg pentamidine, divided into two inhalation phases with the inhalation of 300 mg pentamidin each. In 13 patients (59%) treatment was successful. In five cases, therapy was stopped in the first treatment week because of lacking clinical effectiveness resp. clinical deterioration. In four cases, therapy was discontinued in the further course. The subsequent treatment was successful in all cases. In the case of otherwise good tolerance, in two cases there was a hypoglycemia, in one case with clinical signs. In no case there was any sign of an extrapulmonary pneumocystosis.

Administration, Inhalation↗
PubMed1989

Decreased plasma membrane fluidity of peripheral blood lymphocytes after diethyldithiocarbamate (DTC) therapy in HIV-infected patients.

In seeking the putative mechanism of action of diethyldithiocarbamate (DTC) on the immune status of HIV infected patients, the plasma membrane fluidity of peripheral blood lymphocytes (PBL) from DTC-treated and untreated patients (CDC III-IVc1) was determined. Anisotropy values of the fluorescent probe 6-(9-anthroyloxy) stearic acid were increased in DTC-treated patients (0.175 vs 0.161), indicating decreased PBL plasma membrane fluidity. The membrane rigidifying effect was significantly greater 4 h after i.v. drug administration (0.185 in treated patients). As the membrane fluidity and the function of membrane embedded antigen are interdependent, it is possible that alterations in biophysical and/or biochemical properties of membranes may account for the beneficial effect of DTC on the immune function and clinical status of HIV infected patients.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Maternal criticism, mother-child interaction, and bronchial asthma.

The study investigated maternal critical attitude (CA) and negative mother-child communication in families with an asthmatic child and in controls. Twenty-five children with bronchial asthma (7-13 yr) and 25 healthy children with their mothers participated in the project. Mothers were asked to describe their child (Five Minute Speech Sample; FMSS). Additionally mother and child discussed a mutual problem (Problem Discussion; PD). Videorecordings were taken. CA was assessed from the mothers' responses during FMSS. Negative verbal behavior during PD was coded for mother and child. During FMSS significantly more mothers of the asthmatic children than of the controls showed CA. During PD mothers of the asthmatic children made significantly more critical remarks than their controls. Within the asthmatic group, CA mothers showed significantly more criticisms than those with non-CA. Significantly more long sequences of negative verbal interaction occurred in mother-child-dyads with a CA mother than in those with a non-CA mother.

Adolescent↗
PubMed1989

Elevated tumor necrosis factor alpha and interleukin-6 serum levels as markers for complicated Plasmodium falciparum malaria.

PURPOSE: Tumor necrosis factor alpha (TNF-alpha) has been implicated in the pathology of experimental malaria. To establish its relevance to human malaria, we studied serum levels of two monocyte-derived cytokines, TNF-alpha and interleukin-6 (IL-6), as well as of the lymphocyte-derived mediator interferon gamma (IFN-gamma) in patients with malaria before and during antiparasitic treatment. PATIENTS AND METHODS: One hundred twenty serum samples of 40 patients with malaria (Plasmodium falciparum [n = 32], Plasmodium vivax [n = 8]) were analyzed. IL-6 was measured by a highly sensitive and specific bioassay, TNF-alpha by immunoradiometric assay, and IFN-gamma by radioimmunoassay. RESULTS: Elevated cytokine levels could be detected in the majority of patients with P. falciparum malaria before treatment (31 of 32, 21 of 32, and 21 of 32 for TNF-alpha, IL-6, and IFN-gamma, respectively), but only in some patients with P. vivax malaria (four of eight, one of eight, and zero of eight for TNF-alpha, IL-6, and IFN-gamma, respectively). Serum concentrations of the monokines TNF-alpha and IL-6 correlated significantly with parasitic density (p less than 0.001). No such correlation was obtained with the circulating IFN-gamma concentration. The levels of monokines TNF-alpha and IL-6 were markedly elevated in 18 P. falciparum-infected patients with complicated clinical courses (median values for TNF-alpha 172 pg/mL, for IL-6 16 U/mL, peak values: 896 pg/mL and 1,000 U/mL, respectively). The correlation between TNF-alpha and IL-6 concentrations in serum (n = 40, r = 0.56, p = 0.0002) suggests co-ordinate production of those mediators. CONCLUSION: Organ impairment in human malaria was found to be correlated with the amount of circulating cytokine levels of TNF-alpha and IL-6. Thus, imbalances of the cytokine network in untreated P. falciparum infection serve as markers of severity of disease. Modulation of cytokine response could represent a novel approach to the treatment of severe organ dysfunctions in human malaria.

Adult↗
PubMed1989

In vivo demonstration of a paracrine, inhibitory action of Met-enkephalin on adrenomedullary catecholamine release in the rat.

The present study was an attempt to assess the inhibitory effect of methionine-enkephalin (Met-Enk) on adrenal catecholamine release under in vivo conditions employing a microdialysis system. One adrenal gland of intact male rats was implanted with a microdialysis system. One day after surgery, the adrenal dialysis system was connected to a perfusion pump and Ringer solution or a Ringer solution containing Met-Enk, naloxone (Nal), or a combination of Met-Enk and Nal was used for dialysis; dialysate fractions were collected at 5-min intervals. Catecholamine secretion was stimulated by an iv injection of 1.4 mumol (200 micrograms) acetylcholine (Ach). Met-Enk-immunoreactive material in adrenal medulla extracts and dialysate fractions was analyzed by reverse phase HPLC combined with Met-Enk RIA. Under resting conditions, adrenal release rates of norepinephrine and epinephrine into the Ringer solution were constant. After Ach application secretion of both catecholamines increased about 2.7-fold. Within 10 min after the injection, catecholamine levels returned to baseline levels. Intra-adrenal application of Met-Enk reduced Ach-stimulated epinephrine, but not norepinephrine, secretion significantly; application of Nal did not affect Ach-stimulated catecholamine secretion in the initial fraction after Ach injection, but significantly prolonged amine secretion after the cholinergic stimulus. Application of Nal followed by a combined application of Met-Enk and Nal was without an effect on the amount of catecholamines released in the initial fraction after Ach injection compared to that in the control group. Thus, naloxone prevented the inhibitory effect of Met-Enk on Ach-stimulated CA release. HPLC analysis of adrenal medulla extracts followed by Met-Enk RIA revealed that several forms of Met-Enk are present in chromaffin cells, whereas in adrenal dialysates only one, albeit broad, signal of Met-Enk immunoreactivity was detectable. We demonstrate in vivo a paracrine or autocrine action of Met-Enk on Ach-stimulated catecholamine release by applying the peptide directly into the adrenal gland via a microdialysis system. We conclude that neuropeptides endogenous to the adrenal gland not only reduce the amplitude of catecholamine secretion in response to an Ach stimulus but, in addition, modulate the duration of catecholamine secretion. This is demonstrated by a prolonged catecholamine secretion if opiate receptors are blocked by Nal.

Adrenal Medulla↗
PubMed1989

Ultrastructural analysis of germinal centers in lymph nodes of patients with HIV-1-induced persistent generalized lymphadenopathy: evidence for persistence of infection.

Germinal centers play an important role in the pathogenesis of HIV-1-induced lymphadenopathy. Cell-free retrovirus particles, gag proteins of HIV-1, and cells expressing viral RNA can be detected in these areas of the lymph node. In the present study, the ultrastructural changes and the interactions of virus with different cell types of the germinal centers were investigated. We compared the alterations of lymph nodes obtained shortly after seroconversion with those seen in longstanding lymphadenopathy. The results demonstrated that germinal centers were already infected in the early phase of the disease. However, the number of cell free virions was low. During the course of the disease, large amounts of cell free virions accumulated in the germinal centers. The persistence of germinal center infection for up to 2 years was demonstrated by detecting retrovirus particles in repeated biopsy specimens. In addition, the presence of numerous small, moderately electron dense structures that might represent defective particles of HIV-1 and influence the course of the disease were described. HIV-1 was found to replicate in lymphocytes, macrophages, and follicular dendritic cells. Quite possibly, a genomic shift may occur at the time of transmission of the virus to a novel target cell, thus, germinal centers may be one of the anatomic sites where HIV-1 acquires the ability to develop into a variant with preferential tropism for a given cell type.

AIDS-Related Complex↗
PubMed1989

Retrospective cohort study of cancer morbidity in furniture makers exposed to wood dust.

A retrospective cohort study was undertaken to examine the cancer morbidity in a group of 759 furniture makers of the Neubrandenburg District. During the study interval of 1973 to 1984, a total of 40 malignant tumors occurred in the exposed group. Except for bronchial cancer (SIR = 68) and prostate cancer (SIR = 43), all observed tumors were overrepresented in comparison to the incidence of such illnesses in the normal population of the study area. Significantly increased SIRs occurred for malignant melanoma (2 cases, SIR = 952) and for rectal cancer (6 cases, SIR = 239). Malignant tumors of the nose and paranasal sinuses were not observed.

Air Pollutants, Occupational↗
PubMed1988

Immunohistochemical, electron microscopic and in situ hybridization evidence for the involvement of lymphatics in the spread of HIV-1.

To investigate the role of the lymphatic vessels and the sinus systems of the lymph node in the spread of HIV-1, we evaluated 15 lymph nodes from patients with persistent generalized lymphadenopathy (PGL). Fifteen lymph nodes taken from patients with follicular hyperplasia not related to HIV-1 infection served as controls. Immunohistochemical and in situ hybridization techniques revealed infected cells within the sinuses and the efferent lymphatics of the PGL lymph nodes. In contrast, infected cells could not be detected within the walls of the high endothelial venules nor in the areas immediately adjacent. The parenchymal side of the marginal sinus was lined by a discontinuous endothelium. Macrophages and lymphocytes were located within the gaps of this endothelium. More importantly, when the enlarged follicle extended as far as the wall of the marginal sinus, the processes of follicular dendritic cells could be seen extending through the gaps into the lumen of the sinus. This suggests that these cells could transport antigens (including HIV-1) from the sinuses directly to the germinal centers. In addition, HIV-1 particles within cytoplasmic vacuoles were seen in infected macrophages located in the submarginal zone. Positive cells were also found in the extrafollicular lymphoid parenchyma, especially in the area between the marginal sinus and the follicles. The observed distribution of the virus-positive cells within the PGL lymph nodes strongly implicates the lymphatic vessels in the spread of HIV-1 infection.

Acquired Immunodeficiency Syndrome↗
PubMed1987

[Antibodies against HIV-2 (LAV-II) in Africa and West Germany].

Antibodies against HIV-2 were tested by indirect immunofluorescence in over 2000 sera from Africa and the Federal Republic of Germany. The specificity of the test for HIV-2 was established by absorption of the sera with HIV-1 infected cells. Antibodies against HIV-2 were found in sera from two of 51 Africans who are living in the FRG. In addition, antibodies against HIV-2 were occasionally found in two of 1396 sera from Central Africa and two of 322 from West Africa. Cross-reacting antibodies were found in four of 189 high risk patients from the FRG who had HIV-1 infection, these antibodies no longer being present after absorption. It would therefore seem that HIV-2 infections are still rare among German risk groups.

Absorption↗
PubMed1987

Eosinophil production in human bone-marrow cultures induced by 80-85 kDa serum component(s) of patients with eosinophilia.

Eosinophil production from normal human bone-marrow cells was induced by plasma or serum of patients with eosinophilia. After 10-12 d of liquid suspension culture, 14-42% of bone-marrow cells were identified as maturing eosinophil granulocytes. Upon molecular sieve chromatography, the activity eluted in a single peak corresponding to a substance of 80-85 kDa molecular weight. The activity did not stimulate colony formation in semi-solid agar media, but was detected in liquid suspension cultures only. Furthermore, addition of exogenous colony-stimulating factor (CSF) had a differential effect depending on the culture system used. In semi-solid media, predominance of eosinophil colonies was only observed when CSF was added at a low concentration. In liquid suspension cultures, however, 30-40% of cultured cells were eosinophils independent of the CSF concentration used. These findings extend recent studies in an animal model and support the hypothesis that a differentiation factor is involved in the regulation of eosinophil production in man.

Bone Marrow↗