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Biomedical subjects

A Rieger

Publications and source records attributed to A Rieger.

At least 37 records · Page 2Linked to original sources
PubMed1999

Mycobacteria other than tuberculosis with an emphasis on Mycobacterium xenopi in clinical specimens from AIDS patients at the University Hospital of Vienna from 1989 to 1996.

This study was carried out to provide an overview of the frequency of various mycobacterial species isolated from AIDS patients at the University Hospital of Vienna from 1989 to 1996. Mycobacterium xenopi was found to be the second most common nontuberculous mycobacterial species (92 specimens from 30 patients) and was cultured predominantly from respiratory tract specimens. In 55% of patients, chest X-rays taken at the time of isolation demonstrated pathologic changes which could not be attributed to another cause. Therefore, according to our results, Mycobacterium xenopi should be viewed as an infectious agent rather than a contaminant in AIDS patients.

AIDS-Related Opportunistic Infections↗
PubMed1999

[Is the laryngeal mask a minimally invasive instrument for securing the airway? Supplementary remarks on the paper "Injures and dangers in the use of the laryngeal mask" by V. Hempel, Anaesthesist (1999)48:399-402].

Minor laryngopharyngeal complaints following anaesthesia considerably determine postoperative patient comfort. They cannot be eliminated but reduced by experience and careful preparation and insertion technique. The incidence of minor laryngopharyngeal symptoms following the use of the laryngeal mask airway is similar to that following endotracheal intubation. However, there seems to be a distinct pattern of complaints: discomfort with swallowing is more frequent after LMA, whereas dysphonia is more often observed following endotracheal intubation. The significance of LMA cuff pressures in the pathogenesis of postoperative throat complaints remains unclear. There is sound evidence that cuff pressure is not a representative measure for the effective pressure load upon the pharyngeal mucosa. Measurement of cuff pressure is not obligatory, instead reduction of cuff volume to a "just seal" situation seems to be a reasonable approach. The laryngeal mask airway has definitely changed anaesthesiology airway management. Whether this is due to its supposedly less invasiveness compared to endotracheal intubation has not been proven by scientific investigations.

Humans↗
PubMed1999

A case of HIV-associated cerebral histoplasmosis successfully treated with fluconazole.

Clinically apparent involvement of the central nervous system is a rare event in cases of disseminated histoplasmosis, even in HIV-infected persons. Despite therapy with amphotericin B, mortality remains very high. Reported here is the case of an HIV-infected patient with a 3-month history of fever, cough, weight loss and miliary lung infiltrates. Four weeks after initiation of tuberculostatic therapy, high-grade fever, neurological symptoms, personality changes and respiratory deterioration occurred. Magnetic resonance imaging of the brain showed multiple mass lesions, and a chest radiograph revealed worsening of pulmonary infiltrates. Methenamine silver staining of a lung biopsy specimen demonstrated Histoplasma capsulatum. Subsequently, this pathogen was cultured from lavage fluid. Following high-dose intravenous fluconazole therapy (800 mg once daily), the patient's condition improved markedly within 10 days, followed by an almost complete resolution of pulmonary and cerebral mass lesions. This is believed to be the first documented case of rapid improvement of disseminated histoplasmosis with central nervous system involvement in an HIV-infected patient upon induction of therapy with fluconazole.

AIDS-Related Opportunistic Infections↗
PubMed1999

Control of cytomegalovirus retinitis after combination antiretroviral therapy.

PURPOSE: To report on AIDS patients having combination antiretroviral therapy whose cytomegalovirus (CMV) retinitis remained inactive after discontinuation of anti-CMV maintenance therapy. METHODS: We describe the course of CMV-retinitis in 3 patients with AIDS after initiation of combination antiretroviral therapy. RESULTS: After cessation of anti-CMV therapy no relapse of CMV-retinitis has been observed for up to 18 months. Two of the patients developed new CMV-retinitis in the first months after initiation of combination therapy, nevertheless after further improvement of immunological parameters retinitis remained stable without anti-CMV therapy. CONCLUSION: The sustained immunological effects of combination therapy are possibly sufficient enough to provide protection against CMV-retinitis.

AIDS-Related Opportunistic Infections↗
PubMed1999

Infection of circulating CD34+ cells by HHV-8 in patients with Kaposi's sarcoma.

Human herpesvirus type 8 (HHV-8) has been identified as the most likely candidate to be involved in the development of Kaposi's Sarcoma (KS). HHV-8 has been associated with all forms of KS, primary effusion lymphoma, and multicentric Castleman's disease and detected in various non-neoplastic cells. Its presence in cells of the different hemopoietic lineages has not yet been investigated in a comprehensive and systematic manner. In this study we searched for the presence of HHV-8 in different subpopulations of peripheral blood mononuclear cells (PBMC) from patients with classic and AIDS-associated KS, as well as from HIV-1 sero-positive and sero-negative persons without KS. Thirty-four samples of PBMC were isolated from 30 patients. Subpopulations were isolated with immunomagnetic beads. Polymerase chain reaction for HHV-8 DNA was performed on PBMC and subpopulations with a primer pair selected from ORF26 of the viral genome. Polymerase chain reaction products were subsequently Southern blotted and hybridized. In patients with KS, HHV-8 DNA was detected in nine of 11 (81%) CD19+ cells, four of 11 (36%) CD2+ cells, three of 11 (27%) CD14+ cells, and nine of 11 (81%) of the remaining depleted cell populations (DP) that contain CD34 positive cells. In a subsequent set of experiments HHV-8 DNA was detected in 10 of 12 (83%) CD34 positive cell fractions. All cell subpopulations from the non-KS group were HHV-8 negative, with the exception of one positive B cell sample obtained from an HIV-infected patient. Our data demonstrate that in peripheral blood HHV-8 is detectable not only in CD19+ cells, as previously reported, but also in other cells, including T cells, monocytes, and cells devoid of specific lineage markers. We also show for the first time that CD34+ cells in peripheral blood of KS patients are a predominant HHV-8-harboring population, suggesting that they represent an additional important reservoir for this virus in vivo.

Antigens, CD19↗
PubMed1999

Is it useful to measure supratentorial ICP in the presence of a posterior fossa lesion? Absence of transtentorial pressure gradients in an animal model.

Previous studies with animal models of supratentorial ICP elevation have demonstrated a pressure gradient between the supratentorial and the infratentorial compartments. The present study was designed to investigate the possible presence of such a gradient in the case of infratentorial ICP elevation. An inflatable infratentorial balloon catheter was implanted in seven domestic pigs. The infratentorial ICP (ICPi) was measured in the left cerebellar hemisphere, and the supratentorial ICP (ICPs) was measured in the left cerebral hemisphere. The corresponding pulse amplitudes (ICPi-PA, ICPs-PA) were recorded in both compartments, and the cerebral perfusion pressure (CPP) was calculated. ICPi and ICPs values prior to balloon inflation were 4.4 (SD 2.2) and 4.1 (SD 2.3) mm Hg, respectively, and increased to 63.1 (SD 32.6) and 62.3 (SD 28.1) mmHg after balloon inflation. ICPi-PA rose from 3.1 (SD 0.43) to 12.8 (SD 8.0) mmHg, and ICPs-PA rose from 3.2 (SD 0.63) to 13.0 (SD 7.1) mmHg. CPP decreased from 86.1 (SD 12.0) to 55.4 (SD 14.6) mm Hg. The paired difference between ICPi and ICPs values was 0.44 (SD 1.96) mmHg, and the paired difference of ICP amplitudes was 0.03 (SD 1.19) mmHg. All these differences in infratentorial and supratentorial values were statistically not significant. In conclusion, infratentorial ICP elevation in the presented pig model leads to a uniform ICP elevation in the intracranial space without development of a considerable pressure gradient below and above the tentorium. In the low pressure part of the ICP curve, cerebrospinal fluid connects the compartments and contributes to the pressure equilibrium. The early obstruction of the foramen magnum by intruding cerebellar tissue seems to isolate the infratentorial from the spinal compartment. In the high-pressure part of the curve, the upwards cerebellar transtentorial herniation takes over the pressure transfer, and the whole intracranial space can be considered as a single compartment in the pig.

Animals↗
PubMed1998

Simultaneous continuous measurement of pO2, pCO2, pH and temperature in brain tissue and sagittal sinus in a porcine model.

INTRODUCTION: The clinical use of brain tissue oxygen measurement in patients with severe head injury is increasing. It is important to compare the findings in brain tissue with cerebrovenous blood oximetry, to obtain normal values and to find out limitations of the method. We evaluated a newly available multisensor probe simultaneously in the brain tissue and in the sagittal sinus in a porcine animal model. METHODS: We placed the Paratrend 7-probe (BSL, High Wycombe, UK) in the left frontoparietal white matter and measured pO2 (PtiO2), pCO2 (ptiCO2), pH and temperature while simultaneously measuring these parameters (pcvO2, pcvCO2) in the sagittal sinus in 7 pigs under general anaesthesia during oxygen enhancement. RESULTS: The relation between oxygen increase in brain tissue and in the sagittal sinus showed a coefficient of correlation (CCmean) rmean = 0.96. The quantitative response in brain tissue was much more sensitive than in the sinus. A close correlation between pCO2 in brain tissue and sagittal sinus and the increase of the inspired oxygen was seen: CC ptiCO2 to arterial oxygen pressure (paO2) - rmean = 0.67, CC pcvCO2 to paO2 - rmean = 0.88. CONCLUSIONS: Measuring partial oxygen pressure in brain tissue is more responsive to physiological variations, and the absolute values are more sensitive than oxygen measurement in the cerebrovenous compartment. This is important for interpreting measured values and introducing new coefficients for patient monitoring.

Acid-Base Equilibrium↗
PubMed1998

Temperature of the cerebrovenous blood in a model of increased intracranial pressure.

UNLABELLED: Hypothermia has a considerable protective effect during brain ischemia. On the other hand small increases of brain temperature have a remarkable effect on the exacerbation of neurological damage following an ischemic event. Hyperthermia of the brain tissue after severe head injury is described. The effect of acutely increased intracranial pressure on cerebrovenous blood temperature is not described yet. The aim of this study was to investigate the relationship between temperature in the cerebrovenous compartment (Tcv) and changes of the CPP in an animal model of raised intracranial pressure. METHODS: A thermocouple was inserted in the sagittal sinus in 9 pigs under general anesthesia. By stepwise inflating a supracerebral and infratentorial placed balloon catheter intracranial pressure (ICP) was increased and CPP concomitantly decreased. The central body temperature was measured simultaneously in the abdominal aorta (Ta) with a second thermocouple. RESULTS: In our model th Tcv was lower than Ta at the beginning of the ICP increase. The mean difference between Ta and Tcv, (delta Ta-cv) was 0.86 degree C (+/- 0.44) prior to ICP increase and 1.19 degrees C (0.58) at the maximum ICP increase. Thus, delta Tav increased during CPP reduction. This relation was represented by an adjusted R(square) of r2 = 0.89 (p < 0.001). CONCLUSIONS: The CPP decrease, caused by an increasing ICP, results in changes of the cerebrovenous blood temperature. Interpreting the present results the experimental situation of a relative colder cerebral compartment in comparison to the central body temperature has to be considered. However, the results imply, that simultaneous temperature monitoring of the central body temperature and the cerebrovenous blood temperature is an additional source of information about relative changes of the CBF.

Animals↗
PubMed1998

Comparison between continuous brain tissue pO2, pCO2, pH, and temperature and simultaneous cerebrovenous measurement using a multisensor probe in a porcine intracranial pressure model.

Local brain tissue oxygenation (p(ti)O2) and global cerebrovenous hemoglobin saturation (SjO2) are increasingly used to continuously monitor patients after severe head injury (SHI). In patients, simultaneous local and global oxygen measurements of these types have shown different results regarding the comparability of the findings during changes in CPP and ICP. This is in contrast to theoretical expectations. The aim of this study was to compare p(ti)O2 measurement with cerebrovenous oxygen partial pressure measurement (p(cv)O2) in an animal intracranial pressure model. To this end, a multisensor probe was placed in the left frontoparietal white matter to measure p(ti)O2, pCO2 (p(ti)CO2), pH (pH[ti]), and temperature (t[ti]) while simultaneously measuring these same parameters (p(cv)O2, p(cv)CO2 pH(cv), t[cv]) in the sagittal sinus of 9 pigs under general anesthesia. By stepwise inflating a balloon catheter, placed in supracerebellar infratentorial compartment, ICP was increased and CPP was decreased. The baseline levels of p(ti)O2, p(ti)CO2, and pH(ti) in the noninjured brain tissue showed more heterogeneity compared to the findings in cerebrovenous blood. Both, p(ti)O2 and p(cv)O2 were significantly correlated to the induced CPP decrease. PCO2 was inversely correlated to the course of CPP in both measurement compartments. Temperature measurement showed a positive correlation with CPP in both compartments. These findings demonstrate that brain tissue oximetry and cerebrovenous PO2 measurement are sensitive to CPP changes. The newly available continuous parameters in multisensor probes could be helpful in interpreting findings of cerebral oxygen measurement in man by analyzing the interrelationship of these parameters.

Anesthesia, General↗
PubMed1998

Genus level identification of mycobacteria from clinical specimens by using an easy-to-handle Mycobacterium-specific PCR assay.

An easy-to-handle Mycobacterium-specific PCR assay for detection of the presence of a wide range of mycobacterial species in clinical samples was evaluated. The performance of the genus probe was compared with the performance of probes specific for Mycobacterium tuberculosis and Mycobacterium avium and with that of standard culture. In addition, the utility of an internal control in monitoring amplification inhibitors was studied. Of 545 respiratory and 325 nonrespiratory specimens (a total of 870 specimens), 58 (6.7%) showed the presence of amplification inhibitors, as determined by a negative result for the internal control. Of these 58 specimens, 31 (53%) were stool specimens; other material, even citrate blood after lysis of erythrocytes, did not pose a problem with regard to inhibition of PCR amplification. Eighty-one of the remaining 812 specimens had a positive Mycobacterium culture result. Of these culture-positive specimens, 58 (71.6%) showed a positive result with the Mycobacterium genus-specific probe. Seventy-two samples had a positive result with the Mycobacterium-specific probe but a negative culture result. Of these 72 samples, 26 samples were regarded as true positive, either because the M. tuberculosis- or M. avium-specific probe was also positive at the same time or because other specimens from the same patient taken at the same time were culture positive. The sensitivity of the Mycobacterium-specific probe was 78.5% and the specificity was 93.5%. This study showed that pretesting of clinical specimens for mycobacteria to the genus level with a Mycobacterium-specific probe offers the routine clinical laboratory the possibility of detecting tuberculous and nontuberculous mycobacteria with one test. Furthermore, specimens testing positive with the genus-specific probe can be immediately identified with species-specific probes.

Bronchi↗
PubMed1998

Evaluation of cytomegalovirus retinitis management. Outcome of four years of cytomegalovirus therapy.

Cytomegalovirus (CMV) is the most common pathogen of opportunistic viral infections in patients with the acquired immunodeficiency syndrome. In this study, we assessed the therapeutic outcome of our treatment regimen of CMV retinitis by analysing retrospectively 33 consecutive patients. The clinical utility of CMV cultures from blood, urine and throat specimens obtained at the time of diagnosis was additionally evaluated. Treatment started with ganciclovir (GCV) therapy. In case of relapsing retinitis, re-induction therapy was initiated, and if unsuccessful, the patient was switched to foscarnet. Patients developing resistant retinitis despite foscarnet therapy were offered a GCV-foscarnet combination therapy. Under primary GCV therapy, the median first stable interval of the whole group was 202 days (mean 238 days). Twenty-five out of 33 CMV retinitis patients (76%) responded to initial GCV therapy. Eleven of these patients showed relapsing retinitis that could be stabilised in 3 patients solely with combination therapy. Eight patients did not respond to primary GCV therapy. Three of them improved with foscarnet, but 3 patients did not respond to either treatment. In 18 (56%) out of 32 patients, CMV cultures yielded positive results. Considering our series, we may conclude that in the majority of patients primary or secondary viral resistance can be overcome by dose increase, switching to the alternative drug or a combination therapy.

AIDS-Related Opportunistic Infections↗
PubMed1998

[Antiretroviral drugs 1998/1999].

Combination antiretroviral therapy has proven to be the most effective approach to treat HIV disease. The primary goal of treatment for HIV infection is to achieve maximal and durable suppression of viral replication. After decrease of viral load numerical and functional recovery of the immune system is observed and has been associated with better clinical performance of patients. The number of antiretroviral drugs has increased over the last years and currently 12 compounds are available. Wise combinatorial use of these drugs, extensive information and long-term motivation of patients, regular and correct intake are a prerequisition rather than a guarantee of therapy success. These drugs exhibit several class- and substance-specific short-/long-term toxicities, complex pattern of cross-resistance and drug-drug interactions and therefore in depth knowledge of the pharmacology of antiretroviral drugs is mandatory for primary care providers.

Anti-HIV Agents↗
PubMed1998

[Radiologic aspects of infarction of the appendix epiploica].

Clinical, US, CT and MR findings were reviewed in 5 patients with primary epiploic appendagitis (3 men, 2 women, mean age 38 years, age range 29-62 years) seen between December 1994 and December 1997. Diagnosis was reached in all cases with CT, with US in 3 and with MR in 1. Follow-up CT was performed in 2 cases and clinical follow-up in 4. One patient underwent surgery. Initial US, CT or MR examinations revealed a fatty oval-shaped nodule located anteriorly or anterolaterally to the left colon. The greater diameter ranged from 20 to 30 mm. Perinodular lesions with strands of periappendicular fat and thickened parietal peritoneum were visualized in all cases without any other inflammatory process in the abdomen. Symptoms resolved within 4 days in all patients. Signs of fatty inflammatory processes resolved in the 2 patients who had follow-up CTs. Primary epiploic appendagitis has characteristic US, CT and MR features which help guide medical treatment.

Adipose Tissue↗
PubMed1997

Factors predicting pituitary adenoma invasiveness in acromegalic patients.

Forty-four adult acromegalic patients carrying growth hormone-producing pituitary macroadenomas were investigated with neuroradiological and endocrinological techniques. Plasma growth hormone and somatomedin-C levels were repeatedly measured before surgical removal of tumors and during the follow-up period. Twenty-five patients presented preoperatively with an invasive adenoma that involved the cavernous sinus (CS). Diagnosis of tumor invasivity was made according to distinct neuroradiological criteria and was confirmed or rejected during surgery Significantly higher basal growth hormone levels were found in patients with CS invasion than in cases without tumor growth in the CS. Evidence is presented that plasma growth hormone level in acromegalics is a more sensitive indicator for predicting tumor invasiveness than somatomedin-C. Growth hormone basal values before surgery and the extent of their decrease after removal of tumor correlate with adenoma growth in the parasellar compartments and should be used as a prognostic factor to aid in planing adjuvant tumor treatment.

Acromegaly↗
PubMed1997

Somatostatin receptor scintigraphy in patients with pituitary adenoma.

Presence of high-affinity somatostatin (SST) receptors in most endocrine tumor cells allow in vivo scintigraphic visualization of these neoplasms after intravenous administration of a radionuclide-labeled somatostatin analog. 111In-octreotide is at present the most often used substance for imaging of the SST receptor expression in vivo. The aim of this study is to investigate the correlation between presence of in vivo scintigraphically detectable SST receptors in pituitary tumors and clinical parameters such as patients' age, tumor size, hormonal hypersecretion, and response to octreotide therapy. Forty-two-consecutive patients were enrolled in this trial. Twenty-five of them had nonsecreting pituitary tumors, 11 were acromegalic, and 6 had macro- or microprolactinoma. Scintigraphic images of the head were obtained at 10 min and 24 hours after injection of the radionuclide. In 23 patients, no specific binding of 111In-octreotide was found. Five patients showed a weak positive, 5 had a positive, and 9 a strong positive signal in the region of interest. Uptake of octreotide was significantly correlated with tumor size and age (p < 0.01). Small-size pituitary adenomas were most likely to be scintigraphically receptor-negative, while large suprasellar tumors tended to exhibit a rather strong receptor positivity. Statistical analysis of the data could not confirm the hypothesized correlation between endocrine activity of the pituitary tumors and the scintigraphically proven SST receptor expression in vivo. A positive Octreoscan was not predictive for the result of octreotide therapy.

Acromegaly↗
PubMed1997

[Cerebrovascular fiberoptic catheter oximetry in an intracranial pressure model in swine. New aspects of a clinical routine].

UNLABELLED: The reliability of continuous fibreoptic oximetry in cerebral venous blood and its correlation with intracranial and cerebral perfusion pressures (pressure-volume curve) were examined in an experimental porcine study. METHODS: The pressure in the infratentorial compartment of 13 domestic pigs (18-24 kg) was gradually increased by inflating a Fogarty balloon catheter placed on the surface of the right cerebellar hemisphere and below the tentorium. Single volumes of 0.4 ml saline were injected into the inflatable balloon at 1-min intervals up to a total volume of 7 ml. Intracranial pressure (ICP), arterial blood pressure, cerebral perfusion pressure (CPP), and cerebral venous saturation measured continuously by fibreoptic oximetry and intermittent blood-gas analyses (SjO2 superior sagittal sinus) were monitored during balloon inflation. All data were down-loaded onto a PC and evaluated off-line by a commercial statistical software package. RESULTS: Over the whole pressure-volume curve, two phases of SjO2 behaviour were registered by continuous fibreoptic oximetry (Oximetrix 3, Abbott) (Fig. 1). CPP ranges of less than 50% reduction from the initial value showed a linear correlation (rmittl. = 0.712, P < 0.01) between both parameters (CPP-SjO2). In CPP ranges below a crucial point of about 50 mmHg no such correlation was found (rmittl = 0.176, P < 0.5). In contrast, in 3 pigs a very good correlation was found between CPP and SjO2 over the whole pressure-volume curve as measured by blood-gas analyses of samples from the cerebrovenous catheter (rmittl. = 0.84, P < 0.05). DISCUSSION: We conclude that in physiological CPP ranges down to 50 mmHg, SjO2 measurement is a reliable method of detecting oxygen desaturation in cerebrovenous blood. Below that CPP value, the fibreoptic catheter showed repeated false-high oxygen saturation values. The accuracy of SjO2 measurement seems to depend on sufficient cerebral blood flow (CBF): with decreasing CBF the amount of cerebral venous outflow is diminished. We believe this is why we could not find a correlation in low CPP ranges with the oximetry catheter. This flow-dependency is a new aspect of fibreoptic cerebrovenous oximetry. The authors recommend that rising SjO2 values after desaturation events be confirmed by blood-gas analyses.

Animals↗
PubMed1997

[Continuous measurement of jugular venous blood gas. A case of subarachnoid bleeding].

INTRODUCTION: Recently, a compact multisensor device 0.5 mm in diameter has become available with a miniaturised Clark electrode for measuring blood oxygen tension and two optical fibres for measuring CO2 tension, pH, and temperature (Paratrend 7, Biomedical Sensors, High Wycombe, UK). We used this new probe for continuous blood gas monitoring in the jugular bulb as an alternative to the commonly used fiberoptic spectrophotometric oximetric measurement of haemoglobin saturation. RESULTS: A 64-year-old patient was admitted for surgery of a right-sided intracranial aneurysm. During surgery, with no artefacts or evidence of catheter drift, a normal jugular venous pO2 (pjvO2) of 39 +/- 3 mmHg was measured. Over the period of weaning, two declines in pjvO2 occurred (22.5 and 18.7 mm Hg) associated with a decline in CO2 tension and a rise in pH. We treated these events successfully by analgosedation, controlled ventilation with an inspired oxygen fraction of 70%, and elevation of the mean arterial blood pressure to over 100 mmHg. Extubation was possible about 24 h later. Furthermore, 3 h after extubation pjvO2 values could be monitored without difficulty despite movement of the patient. DISCUSSION: The technique of polarographically measuring pjvO2 with a Clark-type probe appears superior to fibreoptic jugular venous oximetry due to the clearly lower incidence of faulty measurements, especially in the intensive care unit, where patients undergo frequent nursing interventions and tend to awaken. We did not even observe artefacts due to patient movement after extubation. A limitation of the new multisensor system might be the distance of 4 cm between the sensor tip and the end of the insertion catheter, which makes samples drawn for in vitro blood gas analyses to control the continuous monitoring less comparable. Improvements in the construction of the probe are recommended.

Blood Gas Analysis↗