Biomedical subjects
Publications and source records attributed to T Albrecht.
Oral infections with human herpesviruses cause increased morbidity in patients infected with HIV. In this study, multiple HHVs were often isolated from the saliva of HIV-seropositive dental patients, but their isolation rate did not differ substantially from rates reported for the general population, except for human cytomegalovirus.
Increased levels of active sequence-specific DNA-binding proteins, AP-1, CRE/B, and NF kappa B were observed in nuclear lysates of human cytomegalovirus-infected cells from 15 min postinfection. The activation of these cellular factors did not require infectious virus or de novo viral protein synthesis, but their abundance was significantly reduced by inhibitors of protein kinase C and/or A. These data suggest that formation of these transcription factors resulted from the virus-cell membrane interaction and/or through the action of virion structural proteins on cytoplasmic forms of these cellular factors.
OBJECTIVE: A notch ("curare cleft") in the plateau phase of the capnogram of the ventilated patient has been presumed to be a typical early sign of the fading effect of muscle relaxants on the diaphragm. For that reason a prospective study was done to investigate whether capnography can be used diagnostically to indicate the fading effect of vecuronium confirmed by peripheral relaxometry. METHODS: Twenty-five consecutive patients who received inhalation anaesthesia with isoflurane, N2O/O2, and vecuronium during elective neurosurgical procedures were studied. Whenever intraoperative "curare clefts" appeared in the capnogram, diaphragm activity was measured and a simultaneous relaxogram of the adductor pollicis muscle was recorded. After every such event, vecuronium was readministered for complete relaxation. RESULTS: A deformation of the capnogram was registered in 17/25 patients and in all instances (51/51) was caused by diaphragm activity. The deformation disappeared after renewed relaxation and was therefore a reliable indicator of spontaneous breathing. However, it did not correlate with the degree of relaxation of peripheral muscles, because diaphragm activity was present during all degrees of peripheral relaxation, but could also be absent even after complete recovery of neuromuscular transmission. CONCLUSION: Capnography is therefore not a reliable method to indicate the fading effect of muscle relaxants.
Bureau-Barrière syndrome can affect various organ systems. It is defined by the triad: painless ulcers at mechanically irritated and hyperkeratotic plantar areas of the feet, sensitive polyneuropathy of the lower legs and osteolysis in the forefoot area. The condition mainly affects middle-aged men suffering from alcoholism, liver disease, obesity or metabolic disorders such as diabetes mellitus. Successful treatment of the Bureau-Barrière syndrome requires an interdisciplinary approach.
Previous studies suggest that alterations in the microtubule (MT)-tubulin equilibrium during G0/G1 affect mitogenesis. To determine the effect of growth factors on the MT-tubulin equilibrium, we developed a radioactive monoclonal antibody binding assay (Ball et al.: J. Cell. Biol. 103:1033-1041, 1986). With this assay, 3H-Ab 1-1.1 binding to cytoskeletons in confluent populations of cultured cells is proportional to the number of tubulin subunits polymerized into MTs. We now show that purified alpha-thrombin increases 3H-Ab 1-1.1 binding to cytoskeletons of serum-arrested mouse embryo (ME) fibroblasts from 1.5- to 3-fold. This stimulation is dose-dependent and correlates with concentrations of thrombin required for initiation of DNA synthesis. Other mitogenic factors, epidermal growth factor (EGF) and phorbol 12-myristate 13-acetate (PMA), also stimulate MT polymerization. Addition of colchicine (0.3 microM) eight hours after growth factor addition, blocks stimulation of 3H-thymidine incorporation by thrombin, EGF, or PMA, suggesting that tubulin polymerization or subsequent events triggered by MT polymerization are required for cells to enter a proliferative cycle. Consistent with models for autoregulation of tubulin synthesis, thrombin, EGF, and PMA all increase tubulin synthesis 9 to 15 hr after growth factor addition, raising the possibility that the decrease in free tubulin and subsequent stimulation of tubulin synthesis is linked to progression of cells into a proliferative cycle. Colchicine addition to these cells also stimulates DNA synthesis, but colchicine-stimulated cells enter S phase 6 to 8 hr later than those stimulated by growth factors. This delayed stimulation may be related to the time required for degradation of tubulin-colchicine complexes below a critical level. These data suggest that regulation of cell proliferation may be linked to increased MT polymerization and the resulting decrease in free tubulin pools.
Human cytomegalovirus (HCMV) has been shown to increase the frequency of chromosome aberrations, primarily chromatid-type, in human peripheral blood lymphocytes (PBLs). Because HCMV persists in most humans, pathologically activates cells, and may perturb the cell cycle, we investigated the possibility that HCMV-infected cells have a modified sensitivity to chromosome damage induced by genotoxic chemicals. Uninfected PBLs exposed to bleomycin (3 to 100 micrograms/ml) demonstrated a linear increase in the frequency of chromosome aberrations. HCMV infection of PBLs at an intensity that did not cause detectable damage followed by exposure to the same concentrations of bleomycin resulted in a significant enhancement (p less than 0.01) in the frequency of chromosome aberrations relative to the effect of bleomycin alone. A more than additive enhancement of the frequency of chromosome aberrations was also noted in HCMV-infected PBLs exposed to 4-hydroxyaminoquinoline-1-oxide (4-HAQO; 0.1 to 0.3 micrograms/ml) relative to uninfected cells treated with 4-HAQO alone. No increase in the percentage of aberrant cells or the frequency of chromosome aberrations was observed in HCMV-infected cells treated with 4-nitroquinoline-1-oxide (4-NQO) relative to similarly treated uninfected PBLs. These results suggest that HCMV can potentiate the induction of chromosome aberrations in human PBLs caused by potent DNA damaging agents.
The effects of selected DNA repair inhibitors on the frequency of human cytomegalovirus (HCMV)-induced chromosome aberrations were evaluated in human peripheral blood lymphocytes (PBLs). Treatment of HCMV-infected PBLs with camptothecin (0.05 to 0.3 micrograms/ml), an inhibitor of topoisomerase I, for 30 hr resulted in a significant (P less than 0.01) synergistic enhancement of the frequency of HCMV-induced chromosome damage. On the other hand, a significant increase in the frequency of chromosome damage was not noted for infected PBLs treated with either 3-aminobenzamide (3-AB; 3 to 30 micrograms/ml), an inhibitor of poly(ADP-ribose) polymerase, or novobiocin (3 to 30 micrograms/ml), an inhibitor of topoisomerase II or excision repair processes, for 30 hr. Chromatid-type breaks and exchanges were the predominant type of chromosome aberrations observed in the HCMV-infected cells treated with camptothecin, suggesting that HCMV infection is associated with the induction of single-strand DNA breaks. Furthermore, these findings suggest that HCMV infection does not inflict direct DNA damage which is repaired through 3-AB- or novobiocin-sensitive pathways.
The interaction of human cytomegalovirus (HCMV) with the cell membrane has been shown to initiate a cascade of physiologic and biochemical responses that result in the transcriptional activation of specific cellular proto-oncogenes. The cell-activation responses initiated by the virus membrane interaction appear to be important for efficient HCMV replication, as pharmacologic inhibition of cell activation responses significantly reduces the expression of immediate early viral genes and the production of infectious progeny virus. Cellular receptor proteins for other viruses have been shown to be molecules with physiologic activities. Binding of virus to these receptors may trigger the cell to initiate changes that are important for efficient viral replication. These viruses may also trigger inappropriate physiologic responses in the absence of viral replication, thereby causing more covert manifestations of viral pathology.
Delayed replication of human cytomegalovirus (CMV) was initiated in human embryonic fibroblasts using partially ultraviolet light-inactivated virus stock. Cellular [high molecular weight (HMW)] DNA extracted from CMV-infected cell cultures demonstrated a substantial increase in transforming activity after introduction into hamster embryo fibroblasts relative to HMW DNA extracted from mock-infected cells. The transforming activity of HMW DNA varied between 0.01 and 0.25 foci/micrograms DNA. HMW DNA isolated from CMV-infected cells after initiation of viral DNA synthesis demonstrated a significant decrease in the induction of morphologically transformed foci. The transforming activity of HMW DNA was unaffected by HindIII or XbaI endonuclease digestion, but it was sensitive to sonication and EcoRI endonuclease and DNase treatment. Six cell lines were established from the foci of morphologically altered cells. Cells of these lines demonstrated loss of contact inhibition, replication in semisolid agarose or in medium containing low serum, a high saturation density, and tumorigenicity when implanted into hamsters. Histopathological examination of the tumors identified the tissues as fibrosarcomas. In situ hybridization of cells isolated from foci of morphologically altered cells or Southern blot analysis of DNA isolated from either the cell lines or tumors did not demonstrate the presence of sequences with homology to viral DNA using the transforming region or the entire viral DNA as a probe. The lack of viral DNA sequences as well as the similar phenotypic characteristics of cell lines and tumors suggest that alteration(s) induced by CMV may occur in specific region(s) of cellular DNA.
The influence of the inhalational anesthetics halothane, enflurane, and isoflurane on motor evoked potentials was studied in a total of 10 rabbits. Motor evoked potentials were recorded from the extremity muscles as well as from the epidural space of the spinal cord and cauda equina in response to electrical stimulation of the motor cortex at baseline conditions and equianesthetic concentrations (0.25 to 1.5 minimal alveolar concentration). Our results show a dose-dependent suppression of the electromyographic responses, which was similar with all anesthetics. Beyond 0.5 minimal alveolar concentration of any of the agents, electromyographic responses were absent. In contrast, spinal evoked responses representing neural activity were only slightly affected by the anesthetics. We hypothesize that the descending impulse elicited by the electrical stimulation of the motor cortex is mainly inhibited at the level of the spinal interneuronal or motoneuronal systems, because 1) electromyographic responses evoked by the stimulation of the cervical and lumbar nerve roots were only minimally affected by 1.5 minimal alveolar concentration halothane; and 2) spinal evoked responses were stable several minutes after cardiac arrest, indicating a subcortical action site of the electrical impulse. In conclusion, intraoperative monitoring of descending pathways by means of motor evoked potentials during anesthesia with the inhalational agents halothane, enflurane and isoflurane is only feasible when neural activity is evaluated.
The effect on cellular (c) oncogene RNA levels was investigated after infection of permissive cells with cell culture adapted strains (AD-169, C-87, Davis) and unadapted clinical isolates (82-1, 84-2, 85-1) of human cytomegalovirus (HCMV). The results indicate that both adapted and unadapted strains of HCMV induce substantial increases in c-oncogene RNA levels for fos, jun, and myc measured by Northern blot hybridization. Elimination of immediate early (IE) protein synthesis between 0 and 3 hrs or reduction of virus infectivity (99.99%) by UV-irradiation did not reduce the increase in c-oncogene RNA levels. Inhibition of viral and cellular protein synthesis by cycloheximide resulted in a high abundance (superinduction) of specific RNAs which hybridized to c-oncogene probes after infection with either adapted or unadapted strains of HCMV. These data suggest that IE viral gene expression is not essential for activation of c-oncogenes. Inhibition of DNA-dependent RNA synthesis by blocking RNA elongation with actinomycin-D or by inhibiting the activity of RNA polymerase II with alpha-amanitin significantly reduced the increase in c-oncogene RNA levels, suggesting that activation of cellular genes by HCMV is controlled at the level of transcription. Activation of c-oncogenes by HCMV may be particularly important because their protein products appear to be involved in initiation and regulation of viral and cellular gene expression.
The contribution of expression of human cytomegalovirus (HCMV) immediate early (IE) genes to the rapid and transient increase in cellular (c)-oncogene (fos, jun, myc) transcription following HCMV infection was investigated. A partial temporal overlap was observed between the increases in c-oncogene RNA levels and the increase in either transcripts from HCMV IE genes or the number of cells in which HCMV IE proteins were detected. The increases in c-oncogene RNA levels, however, slightly preceded the increase in the detection of HCMV IE transcripts or proteins. To distinguish between the temporal coincidence and a direct relationship between expression of HCMV IE genes and the increased transcription of c-oncogenes, the number of cells synthesizing HCMV IE proteins was reduced by infecting with virus stock enriched in defective particles. Alternatively, the synthesis of HCMV IE proteins was essentially eliminated by ultra-violet (UV) irradiation of virus stock or by inhibitors of protein synthesis. Virus stocks enriched in defective particles demonstrated a substantially reduced capacity to direct the synthesis of HCMV IE proteins, but were more efficient in activating c-oncogene expression than infectious virus stocks. Elimination of expression of HCMV IE genes by UV-irradiation of virus stock or by inhibiting de novo viral and/or cellular protein synthesis with cycloheximide (100 micrograms/ml) or anisomycin (100 micrograms/ml) did not eliminate the HCMV-induced increase in RNA levels of c-oncogenes. These data indicate that activation of these early response cellular genes is independent from de novo expression of HCMV IE proteins, and possibly involves biologically active virion proteins that are related to the induction of a cascade of cellular events associated with the binding of HCMV to its cellular receptor.
The effect of ventilation (normo-, hypo-, and hyperventilation) on transverse sinus pressure (TSP), central venous pressure (CVP), mean arterial blood pressure (mABP), and heart rate was studied in 15 patients undergoing neurosurgical treatment in the sitting position for tumors of the posterior fossa, and the findings were compared with the influence of positive end expiratory pressure (PEEP) on these parameters. TSP was not influenced significantly by PEEP ranging from 0 to 15 mbar, whereas CVP increased. At the same time, mABP decreased slightly. In contrast, TSP showed characteristic changes with varying ventilation: during normoventilation [end expiratory CO2 pressure (PECO2), 38 mm Hg], TSP was 3 mm Hg and increased to 7 mm Hg on average with hypoventilation (PECO2, 44 mm Hg), whereas hyperventilation (PECO2, 32 mm Hg) caused a reduction in TSP to the atmospheric range. At the same time, CVP remained unchanged, whereas mABP increased with hypoventilation. Presuming that the risk of venous air embolism is closely related to the level of TSP, our results allow the following conclusions. 1) PEEP does not seem to be effective in preventing venous air embolism. 2) Hyperventilation is dangerous in the sitting position, as TSP is reduced to the atmospheric and even subatmospheric range. 3) To prevent air embolism, moderate hypoventilation is recommended during the most critical period of exposing the posterior fossa followed by normoventilation when surgery of the actual lesion has begun.
The mechanisms responsible for the human cytomegalovirus (HCMV)-induced increase in cellular oncogene RNAs for c-jun, c-fos, and c-myc in human embryo lung cells (I. Boldogh, S. AbuBakar, and T. Albrecht, Science 247:561-564, 1990) were investigated. Results of transcription assays indicated that the rapid increase in RNA levels for the above-noted oncogenes was controlled at the transcriptional level and was related to enhanced transcription. The maximum rates of transcription for c-jun and c-fos genes occurred at 40 min postinfection, while for the c-myc gene the maximum rate occurred at about 60 min. The magnitude of HCMV-induced activation of these cellular genes was similar to the activation induced by serum. The half-lives of the cellular oncogenes showed similar decay rates after either serum or HCMV activation when measured by dactinomycin chase. The half-life for c-fos or c-jun was about 20 min, and that for c-myc was about 40 min. Furthermore, inhibition of the RNA increase by dactinomycin or by alpha-amanitin suggested that the increase in RNA levels was due to an increase in the transcriptional activity of oncogenes triggered by HCMV.
Amiloride, an inhibitor of Na+/H+ exchange, interfered with cytomegalovirus (CMV) DNA synthesis, blocked the formation of nuclear inclusions, and reduced CMV infectious yields. The reduction of CMV infectious yields was concentration dependent with an ED90 of 46 microM. Amiloride at a concentration of 150 microM reduced CMV yields by about 100-fold. Reduction of infectious yields appeared to be related to interference with the formation of nuclear inclusions and to inhibition of CMV DNA synthesis. Nuclear inclusions were much reduced in size and demonstrated poorly defined cellulae in the amiloride-treated cells. CMV DNA synthesis was inhibited by approximately 70% when cells were treated with 150 microM amiloride. The reduction in CMV yields could not be related to the reported inhibitory effect of amiloride on protein synthesis. In amiloride (150 microM)-treated, CMV-infected cells, late, yet not immediate-early or early, protein synthesis was markedly decreased relative to untreated, CMV-infected cells. Accordingly, CMV DNA synthesis and the replication of CMV may be related to Na+ entry through an amiloride-sensitive pathway.
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During the period from 1984-1988 at the University Clinic, Innsbruck (in cooperation with the Department of Radiotherapy and Surgery) 40 patients with pancreas carcinoma were treated with intraoperative radiotherapy. Based upon the preoperative CT's, the operation reports and the patho-anatomic judgement of the operative specimen for 19 patients the quality of the performed IORT (with curative intention combined with partial pancreaticoduodenectomy) was examined. This examination was based upon a standardized concept. In 53% of the cases the chosen irradiation field was too small and, in most cases the applied single dose was from radiooncological point of view not sufficient. These results emphasize the need for preoperative treatment planning depending from the surgical intention, the need for individually shaped cones and direct field control of the applied dose.
A rapid increase in the RNA levels of the proto-oncogenes c-fos, c-jun, and c-myc was detected after human cytomegalovirus infection. Neither inactivation of viral infectivity with ultraviolet irradiation (with or without psoralen), nor inhibition of translation with cycloheximide or anisomycin adversely affected the enhanced expression of proto-oncogenes, even though these treatments substantially reduced or eliminated the detection of immediate early viral antigens. The increase in the RNA levels of the proto-oncogenes was prevented in the presence of alpha-amanitin or actinomycin D. Thus, expression of these oncogenes appears to be induced by events occurring before the onset of viral protein synthesis, perhaps by the interaction of viral particles with the cell surface.