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Biomedical subjects

P Peters

Publications and source records attributed to P Peters.

At least 19 recordsLinked to original sources
PubMed2005

Inhibition of human immunodeficiency virus-1 (HIV-1) by beta-chemokine analogues in mononuclear cells from HIV-1-infected patients with active tuberculosis.

Tuberculosis (TB) enhances human immunodeficiency virus-1 (HIV-1) activity in patients with dual HIV-1/TB infection. Therapies that control augmentations of HIV-1 activity at sites of Mycobacterium tuberculosis (MTB) infection may be useful in inhibition of viral expansion. Regulated upon activation, normal T-cell expressed and secreted (RANTES) analogues (AOP and NNY) are potent in inhibiting the entry of primary HIV-1 isolates into host mononuclear cells. These analogues were used to inhibit MTB-induced HIV-1 entry in blood monunuclear cells (PBMC) from patients with pulmonary TB, and pleural fluid mononuclear cells (PFMC) from patients with pleural TB. PBMC or PFMC were cultured with and without MTB in presence and absence of RANTES analogues. HIV-1 strong stop DNA was assessed by real-time polymerase chain reaction (PCR) as a measure of infection. CCR5 mRNA was assessed by real-time reverse transcription (RT)-PCR and by immunostaining and FACS analysis. HIV-1 infection was induced by MTB in vitro in PBMC from the majority (14 of 20) of HIV-1/TB subjects, and new infection was inhibited by AOP- or NNY-RANTES. HIV-1 infection was also inhibited by these reagents in MTB-induced PFMC from three of three patients with pleural TB. Expression of CCR5 mRNA was significantly induced by MTB in PBMC from patients with pulmonary TB. Further, expression of CCR5 was higher in PFMC compared to PBMC from patients with pleural TB. Also, CCR5 was fourfold higher on CD14(+) pleural mononuclear cells than on CD4(+) lymphocytes. Blocking new HIV-1 infection of mononuclear cells may be useful in control of HIV-1 during dual HIV-1/TB infection.

Adult↗
PubMed2002

Computer assisted screw insertion into real 3D rapid prototyping pelvis models.

OBJECTIVE: Show the use of computer navigation in exact screw positioning in the different pelvic bones. BACKGROUND: Computer assisted pedicle screw insertion in the spine is an established procedure. Screw fixation is also used in highly difficult pelvic and hip surgery (arthroplasty revision surgery and tumor surgery). DESIGN: Insert as long screws as possible with computer navigation into the different bones of the pelvis and compare these results with a non-computer controlled method. METHODS: The computer navigation was done with the system of Medivision (Oberdorf, Switzerland), the software was SurgiGATE 2.1. Optically controlled spine instruments and a special calibrated drill were used. The screw insertion with and without computer navigation took place in seven real rapid prototyping pelvis models matched by pairs. Three screws were inserted into the Os ileum, one into the Os pubis and one into the Os ischium. The length of the inserted screws were measured and compared using routine statistic methods. RESULTS: The mean screw length with vs. without computer navigation was 8.9 vs. 5.7 cm in the Os ileum (P=0.0001), 6.0 vs. 4.2 cm in the Os pubis (P=0.01) and 4.3 vs. 3.9 cm in the Os ischium (not significant). CONCLUSIONS: The use of computer navigation allows for the insertion of longer screws into the bones of the pelvis (more exact positioning), which requires a more precise original point of entry and direction of the drill (vector). RELEVANCE: The insertion of fixation screws in highly difficult pelvic and hip surgery (revision arthroplasty, tumor surgery) are another field for the use of computer navigation.

Arthroplasty, Replacement, Hip↗
PubMed2001

Increased replication of HIV-1 at sites of Mycobacterium tuberculosis infection: potential mechanisms of viral activation.

Tuberculosis (TB) enhances HIV-1 replication and the progression to AIDS in dually infected patients. We employed pleural TB as a model to understand the interaction of the host with HIV-1 during active TB, at sites of Mycobacterium tuberculosis (MTB) infection. HIV-1 replication was enhanced both in the cellular (pleural compared with blood mononuclear cells) and acellular (pleural fluid compared with plasma) compartments of the pleural space. Several potential mechanisms for expansion of HIV-1 in situ were found, including augmentation in expression of tumor necrosis factor (TNF)-alpha and the HIV-1 noninhibitory beta-chemokine (MCP-1), low presence of HIV-1 inhibitory beta-chemokines (MIP-1 alpha, MIP-1 beta, and RANTES [regulated on activation, normal T expressed and secreted]), and upregulation in expression of the HIV-1 coreceptor, CCR5, by pleural fluid mononuclear cells. Thus, at sites of MTB infection, conditions are propitious both for transcriptional activation of HIV-1 in latently infected mononuclear cells, and facilitation of viral infection of newly recruited cells. These mechanisms may contribute to enhanced viral burden and dissemination during TB infection.

AIDS-Related Opportunistic Infections↗
PubMed2001

Activation of beta-chemokines and CCR5 in persons infected with human immunodeficiency virus type 1 and tuberculosis.

Tuberculosis (TB) in human immunodeficiency virus type 1 (HIV-1)-infected persons is associated with progression of HIV-1 disease. The expression of macrophage inflammatory protein (MIP)-1alpha and CCR5 was assessed in HIV-1-infected patients with pulmonary TB (HIV-1/PTB) and without PTB (HIV-1/C), PTB patients not infected with HIV-1 (PTB), and control subjects. Mycobacterium tuberculosis (MTB)-induced MIP-1alpha production was lower in peripheral blood mononuclear cells (PBMC) of HIV-1/PTB patients than in those of PTB patients (P< .05) and was lower in PBMC of HIV-1/C patients than in those of control subjects (P< .005). However, MIP-1alpha production was higher in PBMC of HIV/PTB patients than in those of HIV-1/C patients (P< .01). The pattern of MTB-induced RANTES production was similar to that of MIP-1alpha. However, MTB induced greater expression of mRNA for CCR5 in PBMC of HIV-1/PTB patients than in those of HIV-1/C patients (P< .04). Furthermore, the MTB-induced HIV p24 antigen level in PBMC of HIV-1/PTB patients with a CD4 cell count <500 cells/microL was higher (P< .05) than that in HIV-1/C patients. Thus, perturbations in chemokine pathways in HIV-1/PTB patients may accelerate HIV-1 disease.

AIDS-Related Opportunistic Infections↗
PubMed2001

Macrophage-activating cytokines in human immununodeficiency virus type 1-infected and -uninfected patients with pulmonary tuberculosis.

Tuberculosis (TB) is the most common opportunistic infection in human immunodeficiency virus type 1 (HIV-1)-infected patients globally and occurs throughout the course of HIV-1 disease. Here the production of interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha by peripheral blood mononuclear cells (PBMC) of HIV-1-infected versus -uninfected patients with newly diagnosed pulmonary TB (PTB) was compared. Findings were correlated with cytokine profiles, clinical presentation, and expression of inducible nitric oxide (iNOS). Most HIV-1/PTB patients with a CD4 cell count of 200-500 cells/microL had high IFN-gamma production and radiographic evidence of atypical PTB. Low IFN-gamma production and radiographic evidence of reactivated PTB characterized both HIV-1/PTB patients with a CD4 cell count >or=500 cells/microL and HIV-1-uninfected patients. TNF-alpha levels were similar in all HIV-1/PTB patients, regardless of CD4 cell count. Induction of iNOS in PBMC was low and was associated with low IFN-gamma production. These data underscore the potential pathogenic role of macrophage-activating cytokines in TB in HIV-1-infected patients.

AIDS-Related Opportunistic Infections↗
PubMed2001

Augmentation of apoptosis and interferon-gamma production at sites of active Mycobacterium tuberculosis infection in human tuberculosis.

Pleural tuberculosis (TB) was employed as a model to study T cell apoptosis at sites of active Mycobacterium tuberculosis (MTB) infection in human immunodeficiency virus (HIV)-coinfected (HIV/TB) patients and patients infected with TB alone. Apoptosis in blood and in pleural fluid mononuclear cells and cytokine immunoreactivities in plasma and in pleural fluid were evaluated. T cells were expanded at the site of MTB infection, irrespective of HIV status. Apoptosis of CD4 and non-CD4 T cells in the pleural space occurred in both HIV/TB and TB. Interferon (IFN)-gamma levels were increased in pleural fluid, compared with plasma. Spontaneous apoptosis correlated with specific loss of MTB-reactive, IFN-gamma-producing pleural T cells. Immunoreactivities of molecules potentially involved in apoptosis, such as tumor necrosis factor-alpha, Fas-ligand, and Fas, were increased in pleural fluid, compared with plasma. These data suggest that continued exposure of immunoreactive cells to MTB at sites of infection may initiate a vicious cycle in which immune activation and loss of antigen-responsive T cells occur concomitantly, thus favoring persistence of MTB infection.

AIDS-Related Opportunistic Infections↗
PubMed2001

[Electronic plantar pressure measurements in different types of moutaineering boots].

Specific footwear has been developed for different, partly newly developed mountain sports. This footwear has very different basic characteristics. This experimental study is dealing with the dynamic parameters of electronic plantar pressure measurements in normal walking using different mountain sport shoes designed for a special purpose in mountaineering. These mountain shoes included a hiking shoe, a trekking shoe and a high-alpine shoe which can take crampons. The electronic plantar pressure measurements were done with the Parotec system of the company Paromed with insoles with hydrocell-sensors. The data obtained during the study were proceeded through a variant analysis. There were no significant differences for impulse and contact time, nevertheless concerning maximal pressure there were significant differences between walking barefoot and walking with the hiking and high-alpine shoe. Even when walking in different mountain shoes the feet conserve their own characteristics and their walking style. The different mountain shoes did not alter most of the measured plantar parameters significantly comparing barefoot walking to walking with the different mountain shoes or comparing walking in the different mountain shoes.

Adult↗
PubMed2001

Nerve compression syndromes in sport climbers.

The aim of this study was to determine and evaluate nerve compression syndromes of the upper and lower extremity in sport climbing. Although considerable research has been conducted on orthopedic problems associated with sport climbing, there has been little comprehensive evaluation of the associated neurological problems. The retrospective study performed on 83 active sport climbers presenting with complaints of the upper or lower extremity showed that 21 climbers (25.3%) were diagnosed with a nerve compression syndrome, 14 climbers of the upper extremity, 7 climbers of the lower extremity. Most nerve compression syndromes could be treated by combined conservative modalities (nonsteroidal anti-inflammatory drugs, ice, splinting, physical therapy, rest or decreased training with a rehabilitation training program) and changes in climbing patterns (scientific training planning with warming up and cooling down as well as stretching exercises, longer rest periods, different hand positions, appropriate climbing shoes). Surgical decompression was rarely necessary. Nerve compression syndromes must be included in the general spectrum of medical problems associated with sport climbing.

Adult↗
PubMed2001

Orthopedic problems in sport climbing.

Sport climbing is associated with unique upper- and lower-limb injuries involving predominantly the hand, elbow, and shoulder, and to a lesser extent the foot. Many pathologic conditions are limited to sport climbing. Physicians treating sport climbers should be aware of these unique injuries and overuse syndromes. This article presents an overview of orthopedic problems (injuries, overuse syndromes, and fractures) resulting from sport climbing. Sport climbing is defined in the context of existing mountain sports, and its characteristics and technical terms are presented. The etiology, diagnosis, and specific treatment for orthopedic problems associated with sport climbing are described.

Athletic Injuries↗
PubMed2000

Practical aspects in mountain medicine education.

Mountain medicine education is provided through many different courses. The newest developments include an international Union Internationale des Associations Alpinistes--Internationale Kommission für Alpines Rettungswesen--International Society of Mountain Medicine (UIAA-IKAR-ISMM) label for mountain medicine courses that comply with certain minimal requirements in theoretical and practical educational aspects. Participants in the courses that fulfill these specific conditions are eligible to obtain the International Diploma of Mountain Medicine, which is recognized by the above-mentioned international bodies governing mountain sports and mountain medicine. The Swiss course cycle, and especially the structure and content of the Swiss summer course 1999, which was organized by the Swiss Alpine Club and the Swiss Society for Mountain Medicine, are described in this article and some annotations are given. Theoretical and practical requirements for obtaining the International Diploma of Mountain Medicine in Switzerland are also presented.

Curriculum↗
PubMed2000

Complications and side effects of hyperbaric oxygen therapy.

BACKGROUND: Despite ongoing controversy, hyperbaric oxygen (HBO) therapy is frequently administered in various clinical situations. Probably because of the unique atmospheric conditions to which the patient is exposed, there are concerns about the safety aspects of this therapy. Possible complications during HBO therapy include barotraumatic lesions (middle ear, nasal sinuses, inner ear, lung, teeth), oxygen toxicity (central nervous system, lung), confinement anxiety, and ocular effects (myopia, cataract growth). METHODS: To analyze the medical safety of HBO therapy, this report reviewed complications and side effects of 782 patients treated for various indications with a total of 11,376 HBO therapy sessions within a multiplace chamber. The absolute treatment pressure was 240 or 250 kPa 114 or 15 msw). The compression was performed in a linear manner with 14 to 15 kPa (1.4 to 1.5 msw) x min(-1). All data were gathered prospectively within a special database. RESULTS: More than 17% of all patients experienced ear pain or discomfort as an expression of problems in equalizing the middle ear pressure. Most episodes were not related to a persistent eustachian tube dysfunction since they only occurred once. Barotraumatic lesions on visual otological examinations (ear microscopy) were verified in 3.8% of all patients. Patients with sensory deficits involving the ear region need special attention, because they seem to be at risk for rupture of the tympanic membrane (three cases documented). A barotrauma of the nasal sinuses occurred rarely and no barotraumatic lesions of the inner ear, lung, or teeth were noted. Oxygen toxicity of the CNS manifested by generalized seizures affected four patients without any recognizable risk factors or prodromes. None of the patients suffered recurrences or sequelae. Regular checks of the blood glucose in diabetics failed to reveal episodes of hypoglycemia as a cause for seizures. Lung function tests of patients undergoing prolonged treatment (average 52.8 sessions) did not deteriorate. CONCLUSION: Patients scheduled for HBO therapy need a careful pre-examination and monitoring. If safety guidelines are strictly followed, HBO therapy is a modality with an acceptable rate of complications. The predominant complication is represented by pressure equalization problems within the middle ear. Serious complications rarely occur.

Adolescent↗
PubMed1999

Apoptosis and T cell hyporesponsiveness in pulmonary tuberculosis.

Mycobacterium tuberculosis (MTB)-induced T cell responses are depressed in peripheral blood mononuclear cells of persons with newly diagnosed pulmonary tuberculosis (TB), and levels of interferon (IFN)-gamma remain low even after completion of antituberculous therapy. Loss of MTB-reactive T cells through apoptotic mechanisms could account for this prolonged T cell hyporesponsiveness. T cell apoptosis was studied in TB patients and healthy control subjects. Both spontaneous and MTB-induced apoptosis (in CD4 and non-CD4 T cells) from TB patients was increased when compared with healthy control subjects, whereas coculture with control antigen (candida) had no effect on T cell apoptosis in either group of study subjects. An inverse correlation existed between increased MTB-induced T cell apoptosis and IFN-gamma and interleukin (IL)-2 immunoreactivities. Successful antituberculous chemotherapy resulted in a 50% reduction in both spontaneous and MTB-induced apoptosis, which coincided with 3- and 8-fold increases in levels of MTB-stimulated IL-2 and IFN-gamma, respectively. These data indicate that apoptotic pathways are operant during active MTB infection and may contribute to deletion of MTB-reactive T cells and the immunopathogenesis of this disease.

Apoptosis↗
PubMed1999

Double-blind placebo-controlled study of concurrent administration of albendazole and praziquantel in schoolchildren with schistosomiasis and geohelminths.

A double-blind placebo-controlled study of the concurrent administration of albendazole and praziquantel was conducted in>1500 children with high prevalences of geohelminths and schistosomiasis. The study sites were in China and the Philippines, including 2 strains of Schistosoma japonicum, and 2 different regions of Kenya, 1 each with endemic Schistosoma mansoni or Schistosoma haematobium. Neither medication affected the cure rate of the other. There was no difference between the side effect rate from albendazole or the double placebo. Praziquantel-treated children had more nausea, abdominal pain, and headache but these side effects were statistically more common in children with schistosomiasis, suggesting a strong influence of dying parasites. The subjects were followed for 6 months for changes in infection status, growth parameters, hemoglobin, and schistosomiasis morbidity. In all 4 sites, a significant 6-month increase in serum hemoglobin was observed in children who received praziquantel, strongly supporting population-based mass treatment.

Adolescent↗
PubMed1999

Depressed T-cell interferon-gamma responses in pulmonary tuberculosis: analysis of underlying mechanisms and modulation with therapy.

Immunological and clinical profiles were evaluated in 2 groups: human immunodeficiency virus (HIV)-uninfected and HIV-infected patients, with newly diagnosed pulmonary tuberculosis (TB), and tuberculin-skin-test-reactive healthy control subjects. HIV-uninfected patients with TB were also followed up longitudinally during and after chemotherapy. At the time of diagnosis, purified protein derivative (PPD)-stimulated production of interferon (IFN)-gamma by peripheral blood mononuclear cells from TB patients was depressed, compared with that of healthy control subjects, whereas levels of transforming growth factor (TGF)-beta and interleukin (IL)-10 were increased. In longitudinal studies, PPD stimulated production of IL-10 and TGF-beta returned to baseline by 3 months, whereas IFN-gamma production remained depressed for at least 12 months. These data indicate that the immunosuppression of TB is not only immediate and apparently dependent (at least in part) on immunosuppressive cytokines early during the course of Mycobacterium TB infection but is also long lasting, presumably relating to a primary abnormality in T-cell function.

Adolescent↗
PubMed1999

[When should a patient with severe acute respiratory distress syndrome (ARDS) be transferred to a specialized hospital?].

The mortality rate for the advanced adult respiratory distress syndrome is still high. Nevertheless there are recent publications showing decreasing incidence and an improving survival rate. This is due to early diagnosis as well as differentiated treatment concepts. The use of special therapy methods including extracorporal gas exchange is only possible at specialized centres. This raises the question as to the right timing of the transfer of those ARDS-patients, whose lungs cannot be cured by the therapy standards practiced locally. In a prospective study, all requests for transfer were noted over a period of 36 months (1992 to 1994) and analyzed by a hospital with a special ward for ARDS. In a total of 469 patients the most prominent predisposing diseases were community-acquired pneumonia (26.3%), followed by multiple trauma (24.4%), the postoperative conditions of systemic inflammatory response syndrome (SIRS) or sepsis (21.3%), bronchopulmonary aspiration (5.8%), and status asthmaticus (2.6%). With a mean preventilation time of 9.5 +/- 9 days and a mean ventilatory peak pressure of 39 +/- 8 cm H2O there was a mean oxygenation index (Horrowitz Index) of 95 (+/- 40) mm Hg. The mean Smith and Gordon Ventilator Score was 82.3 (+/- 12.8) and the mean PIF rate (Benzer Score) 12 (+/- 8.6), 121 out of 469 patients were transferred for further specialized therapy. 75 patients were treated on a conventional basis and 46 patients had to be treated with extracorporal lung assistance (ELA) because conventional treatment failed. The mortality rate was 22.3% altogether, in the group with the conventional treatment 16.0% and 32.6% in the group with ELA. As there are no generally accepted guidelines for the transfer of patients with ARDS to specialized centres, an indication for such a transfer must be established taking into consideration the individual patient history. Very early contact with the specialized centre of choice is recommended.

Adolescent↗