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Biomedical subjects

P Hartmann

Publications and source records attributed to P Hartmann.

At least 37 records · Page 2Linked to original sources
PubMed2001

Expression and distribution of vasoactive intestinal polypeptide receptor VPAC(2) mRNA in human airways.

SUMMARY: Vasoactive intestinal polypeptide (VIP) is a putative neurotransmitter of the inhibitory non-adrenergic non-cholinergic nervous system and influences many aspects of mammalian airway function. VIP binds to two G-protein-coupled VPAC receptors that are highly homologous structurally but distinguished by their different affinities for peptide analogues of VIP. As VIP binding sites in the respiratory tract have only been examined by ligand binding and cytochemical techniques, we studied the distribution of the mRNA that encodes the inducible receptor subtype VPAC(2) in the human respiratory tract. Northern blots demonstrated the expression of VPAC(2) mRNA in human airways and other tissues. A human-specific VPAC(2) cRNA probe was used to detect VPAC(2) mRNA expression in human lung by nonradioactive in situ hybridization. In larger airways, positive VPAC(2) mRNA signals were localized to tracheal and bronchial ciliated epithelial cells. There was also marked staining of mucous and serous cells of submucosal glands. No signals were obtained in airway and vascular smooth muscle myocytes and endothelial cells. In peripheral lung tissues, VPAC(2) mRNA expression was localized to epithelial cells of the bronchioles. Specific staining was detected in immune cells and alveolar macrophages. In summary, VPAC(2) is localized in airway epithelial, glandular, and immune cells of the lung but not in airway and vascular smooth muscle. The absence of VPAC(2) mRNA in vascular and airway smooth muscle myocytes may indicate that the effects of VIP on vasodilation and bronchodilation are mediated by VPAC(1) or undefined receptors. However, a paracrine modulation of the two most prominent effects of VIP in the respiratory tract by VPAC(2) cannot be excluded.

Binding Sites↗
PubMed2001

Lactogenesis and the effects of insulin-dependent diabetes mellitus and prematurity.

The initiation of lactation (lactogenesis II) by the mother must be synchronized to the delivery of the infant, permitting the transition of the newborn from continuous nourishment from the umbilical cord to comparable but intermittent life support from its mother's breasts. The onset of lactogenesis II can be adversely affected by a variety of factors. Over 80% of women who have delivered prematurely and are expressing milk for their infant had a compromised initiation of lactation, that is one or more lactogenesis II markers (lactose, citrate, sodium and total protein) in their milk > 3 SD from the mean of the full-term women on d 5 postpartum. Similarly, the lactogenesis II markers (lactose, citrate and total nitrogen) in the milk of women with insulin-dependent diabetes mellitus take an additional 24 h to attain the concentrations of normal women. The mechanisms that lead to the development of delayed or compromised onset of lactogenesis II in women are poorly understood and require additional research.

Animals↗
PubMed2001

Phagocytosis and killing of Mycobacterium avium complex by human neutrophils.

Organisms belonging to the Mycobacterium avium complex (MAC) cause life-threatening bacteremia in immunocompromised patients. Monocytes and macrophages are thought to be responsible for ingestion and killing of MAC. However, it has been suggested that neutrophils may play a role in the early immune response to MAC infection. Here, neutrophils in autologous plasma were incubated (at 0 and 37 degrees C) with M. avium labeled with Auramine O, a potent fluorochrome. Neutrophil phagocytosis was measured by flow cytometry. Neutrophils incubated at 37 degrees C showed an increase in fluorescence over time with a maximum at 15 min, whereas neutrophils on ice showed no time-dependent increase in FL1. At 15 min Fl 1 at 37 degrees C was twice as high as FL1 at 0 degrees C. Examination under the fluorescent microscope showed multiple intracellular fluorescent mycobacteria. Results in nine independent experiments showed time-dependent decrease of colony-forming units in neutrophil-associated live M. avium. Significant killing was observed within 30 min and was complete by 120 min. Observation by electron microscopy clearly confirmed the presence of intraphagosomal MAC, both intact and with evidence of degradation. These data demonstrate that MAC is rapidly phagocytized and killed by human neutrophils. The newly established flow cytometry method should be useful in further studies of neutrophil function and of the role of G-CSF and other cytokines in MAC disease.

Adult↗
PubMed2000

Photochemically induced energy-transfer effects on the decay times of ruthenium complexes in polymers

The effects of photobleaching on absorption properties and decay times of ruthenium complexes adsorbed on silica gel or dissolved in polystyrene or PVC are reported. While complexes with bipyridyl ligands adsorbed on silica gel did not show any decay time decrease at all, complexes having phenanthroline ligands exhibit a significant photodegradation which is manifested not only by a decrease in luminescence intensity but also by decay time decrease and specific absorption spectral changes. The effects are shown to depend strongly on the oxygen and dye concentrations present at the bleaching process. The absorption bands of the photoproducts of ruthenium-phenanthroline complexes overlap with the emission spectra of the intact molecules. Forster resonance energy transfer from intact ruthenium complexes to their own photoproducts, generated by singlet oxygen attack of the phenanthroline bridges of the ligands, is suggested to be responsible for the observed decay time effects.

Journal Article↗
PubMed2000

[Fast prophylaxis for last-minute travelers. Which measures are still possible 1 week before traveling?].

Vaccinations or booster injections against tetanus, diphtheria and polio shortly before leaving on a journey are both possible and to be recommended. Active hepatitis-A-vaccination can also be applied immediately prior to the journey, and offers better protection than gamma globulins. As a rule, vaccinations against hepatitis B, yellow fever and typhoid must be given one to four weeks before the journey. Effective malaria prophylaxis for last-minute travellers is always possible. In addition to mandatory "exposure prevention", effective chemoprophylaxis is also recommended for travellers to tropical Africa. The dose of the first week should, whenever possible, be taken prior to the start of the journey.

Communicable Disease Control↗
PubMed2000

Fatal thrombotic thrombocytopenic purpura as a rare complication following allogeneic stem cell transplantation.

Thrombotic thrombocytopenic purpura (TTP) is a rare disease which, together with hemolytic uremic syndrome, is subsumed under thrombotic microangiopathy. After stem cell transplantation (SCT), this syndrome represents a possibly fatal complication with a higher incidence in allogeneic SCT than in autologous SCT. Although plasmapheresis offers an encouraging treatment modality in classic TTP, this seems less effective in bone marrow transplant-associated microangiopathy. This is probably due to a different etiology. We present a case of transplant-associated TTP with a fatal outcome despite multiple courses of plasmapheresis.

Fatal Outcome↗
PubMed2000

Through-bond connectivity in solids by continuous-wave spin lock.

A simple two-dimensional correlation experiment that enables determination of through-bond connectivity in the solid state is described. The experiment is performed under fast magic angle spinning (MAS) conditions. After the initial pi/2 pulse, the magnetization develops freely under the MAS Hamiltonian. The t1-period is followed by a strong spin locking pulse used as mixing period. The dipolar coupling is averaged out by magic angle spinning, and the chemical shifts and r.f.-offsets are scaled by the applied spin locking field. Hence, for strong locking conditions, the isotropic J-coupling is the dominant interaction. The mixing Hamiltonian is thus identical to the well-known TOCSY-Hamiltonian, resulting in a net through-bond magnetization transfer. The mixing-time dependence of the exchange rates is investigated. Applications to crystalline P4S7 and MgP4O11 are shown.

Magnesium Compounds↗
PubMed2000

Differentiation, proliferation and adhesion of human neuroblastoma cells after treatment with retinoic acid.

Because of the known property of spontaneous regression in stage IVS of neuroblastoma all attempts are made to elucidate whether differentiation inducers possibly could be applied for neuroblastoma therapy. Here we examined the influence of retinoic acid (RA) in vitro on differentiation, proliferation and adhesion of 10 permanent and 4 primary cell lines as well as of several SCID-mouse tumour transplants. In general, after RA treatment morphologically different cell types which are characteristic for neuroblastoma cells have changed. N (neuronal)-type cells prolonged their neuronal processes, whereas S (epithelial, substrate-adherent, Schwann cell-like)-type cells lost their adherence to substratum and became apoptotic. Additionally, the reactions of all neuroblastoma cell lines with monoclonal antibodies against beta-tubulin (for neuronal cells) and glial fibrillary acidic protein (for epithelial cells) were determined. The anti-proliferative effect of all-trans-RA as well as 13-cis-RA was more profound in S-type cells (up to 40% in primary cell lines). To elucidate the role of adhesion molecules during neuronal cell differentiation, we have analysed the adhesion of neuroblastoma cells on poly-D-lysin-precoated plates under RA influence. While N-type cells displayed an increased adhesion, all S-type cell lines as well as all primary cell lines exhibited a reduced adhesion (IMR-5 and IMR-32: p < 0.001; JW, SR and PM: p < 0.05). RA treatment increased predominantly the tested antigens (HCAM, ICAM-1, NCAM, PECAM-1, VCAM-1, cadherin, FGF-R, IGF-R, NGF-R, TGF-beta/1, NF200, NF160, NF68, NSE, HLA-ABC) in all cell lines independently of their phenotypes (TGF-beta/1: p < 0.001; NF68: p < 0.01; PECAM-1 and NGF-R: p < 0.05). In recultured SCID-mouse-passaged tumour cells antigens were down-regulated (FGF-R: p < 0.01), but increased again after RA influence (TGF-beta/1: p < 0.05). In summary, the RA differentiation model demonstrates the possibility to interfere in cell adhesion and to diminish growth potential both in N-type as well as S-type neuroblastoma cells.

Animals↗
PubMed2000

Long-term excessive magnesium supplementation is deleterious whereas suboptimal supply is beneficial for bones in rats.

The long-term effects of a suboptimal magnesium supply inducing a marginal or moderate deficiency or of an excessive magnesium supplementation corresponding to a basal diet with a high pharmacological intake were investigated in 36 growing Sprague-Dawley female rats. The rats were randomly divided in three groups and received a purified diet with 7 g calcium, 5 g phosphorus and either 0.2, 0.5 or 2 g magnesium per kg diet for 7 months. At the end of the trial, plasma and erythrocyte total magnesium concentrations were significantly lower in the magnesium-deficient group than in the respective control group. Serum concentrations of 1,25-dihydroxyvitamin D, PTH and IGF-I and the length of the right humeri were not affected by the dietary treatment. The volumes corrected for body weight, the medio-lateral diameters and the ratios dry weight/length of the right humeri, and the dry weight corrected for body weight of the left tibiae and of the right humeri were significantly smaller in the magnesium-supplemented group than in the two other groups. The magnesium contents of the left tibiae and of the first lumbar vertebrae were significantly lower in the magnesium-deficient group than in the two other groups. In the right femora, dual energy X-ray absorptiometry revealed significantly smaller areas in the proximal part and significantly smaller mineral contents in the second proximal quarter in the magnesium-supplemented group compared with the two other groups. Peripheral quantitative computer tomography of the right humeri revealed in the cortex significantly larger values for the relative area, mineral content, mineral density and thickness in the magnesium-deficient group compared with the control group. The maximum point of the load-deformation curve was significantly reduced in the fifth lumbar vertebrae and in the proximal femoral metaphyses of the magnesium-supplemented group. These results indicate that the long-term suboptimal magnesium supply improved some of the parameters indicators of bone health whereas the long-term supplementation was deleterious.

Animals↗
PubMed1999

[Meningococcal sepsis in 3 young men].

HISTORY AND CLINICAL FINDINGS: Three young men became ill one after the other with fever, headaches, vomiting, arthralgias and muscle pain. One day after beginning of symptoms all three patients developed a haemorrhagic rash with petechial and ecchymotic lesions most intense on distal extremities. 24 hours later patient no. 1 and 3 were in septic shock. INVESTIGATIONS: Laboratory tests showed signs of systemic infection, disseminated intravascular coagulation and renal failure. On the day of admission to the hospital blood cultures showed Neisseria meningitidis in patient no. 1 and 3. In patient no. 2 blood cultures were negative. TREATMENT AND COURSE: Intravenous antibiotic therapy was started immediately after admission. In patient no. 1 and 3 purpura fulminans with multiple organ failure demanded intensive care treatment. Patient no. 1 recovered. Necrotic toes made amputations necessary. Patient no. 2 was never critically ill. Patient no. 3, whose course was complicated by a long lasting disseminated intravascular coagulation, died from massive cerebral bleeding 6 days after admission. Patient no. 2, who was treated with ciprofloxacin after symptoms began was never critically ill. CONCLUSION: Neisseria meningitidis sepsis has a high mortality rate. Rapid admission to the hospital and beginning of an antibiotic therapy with penicillin G or a third-generation cephalosporin is a priority when meningococcal disease is suspected. Chemoprophylaxis should be offered to close contacts of patients.

Acute Disease↗
PubMed1999

Immunological defense mechanisms in tuberculosis and MAC-infection.

Protective immunity to mycobacterial infections develops in immunocompetent hosts after activation of alpha beta- and gamma delta-T cells in association with the generation of a protection-specific cytokine profile that stimulates the bactericidal potential of the macrophages. The maintenance of a delicate balance between Th1 and Th2 response is decisive for infection control and prevention of exacerbation of disease. Mycobacterial infection in the immunocompromised host is mainly due to the diminished cellular immune function. In addition, nontuberculous mycobacteria isolated from AIDS patients have special virulence factors that promote development of disease by further compromising the function of an already damaged cytokine network.

AIDS-Related Opportunistic Infections↗
PubMed1999

Off-angle correlation spectroscopy applied to spin-1/2 and quadrupolar nuclei.

A two-dimensional correlation experiment is described, in which homonuclear dipolar couplings are used to realize through-space magnetization exchange on spin-1/2 (31P) and on quadrupolar nuclei (23Na and 11B). In the detection period, Magic Angle Spinning is applied to enhance resolution, and the dipole couplings are re-introduced in the mixing period by spinning off the Magic Angle. The dependency of the exchange rates on the mixing time and the spinning angle is investigated. The influence of strong spin-locking during mixing is discussed, and shown in the spin-1/2 case to remove the dependence on chemical shift offset effects. For quadrupolar spins, the experiment yields information on the relative tensor orientations of the coupled quadrupoles. Applications to crystalline sodium aluminum diphosphate, sodium sulphite, and potassium borate glasses are shown.

Boron↗
PubMed1999

A powerful DNA extraction method and PCR for detection of microsporidia in clinical stool specimens.

The diagnosis of intestinal microsporidiosis has traditionally depended on direct visualization of the parasite in stool specimens or intestinal biopsy samples by light and/or electron microscopy. Limited information about the specificity and sensitivity of PCR for the detection microsporidia in clinical stool specimens is available. To establish a sensitive and specific method for the detection of microsporidia in clinical samples, we studied clinical stool specimens of 104 randomly selected human immunodeficiency virus-infected patients with diarrhea to compare light microscopy and PCR. Fluorochrome Uvitex 2B staining was used for light microscopy. To raise the sensitivity of PCR, we used a powerful and fast DNA extraction method including stool sedimentation, glass bead disruption, and proteinase K and chitinase digestion. PCR was performed with primer pairs V1-PMP2, V1-EB450, and V1-SI500, and the nature of the PCR products was confirmed by Southern blot hybridization. Microsporidiosis was diagnosed by light microscopy in eight patients. Ten patients tested positive for microsporidiosis by PCR. Enterocytozoon bieneusi was found in seven cases, and Encephalitozoon intestinalis was found in four cases. In one case a double infection with E. bieneusi and E. intestinalis was diagnosed by PCR, whereas light microscopy showed only E. bieneusi infection. PCR testing of stool specimens is useful for diagnosis and species differentiation of intestinal microsporidiosis in HIV patients.

AIDS-Related Opportunistic Infections↗
PubMed1998

Asymptomatic pneumatosis intestinalis and free abdominal air in a patient with AIDS.

Detection of free abdominal air requires in most cases immediate surgical intervention. However, there may be situations, where invasive procedures are not indicated. We present a case of asymptomatic pneumatosis intestinalis and free abdominal air in a patient with Aids. Pneumatosis intestinalis is a rare entity with accumulation of subserosal or submucosal gas occurring in the small or large bowel. It has been reported in a variety of gastrointestinal disorders, in Aids, after transplantation, with steroid use, and in association with leukemia, lymphoma, vasculitis, collagen vascular disease and chronic obstructive pulmonary disease.

Abdomen↗
PubMed1998

Raynaud's phenomenon and acral necrosis after chemotherapy for AIDS-related Kaposi's sarcoma.

Raynaud's phenomenon is a common vascular side effect of chemotherapy drug regimens. Chemotherapy-induced Raynaud's phenomenon leading to acral gangrene has rarely been reported. In this report, one patient who developed gangrene after bleomycin and vincristine/vinblastine chemotherapy for AIDS-related Kaposi's sarcoma and another HIV-infected patient who exhibited symptoms of severe Raynaud's phenomenon related to the same regimen are presented. Because the combination of bleomycin and vinca alkaloids is commonly used for the treatment of AIDS-related Kaposi's sarcoma, clinicians should be aware of the risk of provoking acral necrosis in patients who develop Raynaud's phenomenon under chemotherapy. The literature is reviewed, and clinical symptoms, pathophysiology, and treatment options are discussed.

AIDS-Related Opportunistic Infections↗