Disconnecting a ventilator at the request of a patient who knows he will then die: the doctor's anguish.
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Aged↗
Biomedical subjects
M J Edwards
Publications and source records attributed to M J Edwards.
Interleukin 2 acutely induces platelet and neutrophil-endothelial adherence and macromolecular leakage.
The acute effects of interleukin 2 (IL-2) were determined in the rat cremaster microcirculation model by intravital, light, and electron microscopy to better understand the pathophysiology of the IL-2-induced vascular leak syndrome. Four groups of rats were studied over a 2-h monitoring period. One group received 1 x 10(6) units of IL-2/kg i.v. (n = 10), while the remaining groups received IL-2 topically applied to the cremaster muscle in dosages of either 1 x 10(5) (n = 9), 1 x 10(6) (n = 5), or 3 x 10(6) (n = 5) units. Each group was compared with controls (n = 9). IL-2 administered i.v. acutely induced platelet and polymorphonuclear leukocyte-endothelial adherence and microvascular macromolecular leakage that occurred synchronous with the development of tachycardia, hypotension, tachypnea, and hypoxemia. Topically applied IL-2 induced similar microvascular alterations but without changes in hemodynamic and respiratory parameters, which suggests that microvascular alterations were not caused by IL-2-induced changes in hemodynamic parameters. Electron microscopy of cremaster muscle sections demonstrated platelet and neutrophil adherence to the endothelium and endothelial injury. We conclude that IL-2 (or a locally generated mediator) acutely induces platelet and neutrophil-endothelial adherence in the rat skeletal muscle microcirculation that is associated with the development of macromolecular leakage from the microcirculation.
Administration, Topical↗
Recurrence of lethal osteogenesis imperfecta due to parental mosaicism for a mutation in the COL1A2 gene of type I collagen. The mosaic parent exhibits phenotypic features of a mild form of the disease.
We have determined that a man, ascertained because he fathered a child with lethal osteogenesis imperfecta (OI) with each of two partners, is mosaic in both his germline and somatic tissues for a mutation in the COL1A2 gene which encodes the pro alpha 2(I) chain of type I procollagen. His dermal fibroblasts were previously shown to synthesize a population of cysteine-containing alpha 2(I) chains that were posttranslationally overmodified. DNA sequence analysis of COL1A2 cDNAs demonstrated that the cysteine-containing chain resulted from a point mutation (G to T) in the first position of the codon for the glycine at residue 472 of the triple helical domain. Genomic DNA from the one available affected infant contained the mutant and normal COL1A2 alleles in equal proportion. Examination of DNA from several tissues of the father showed that the mutant allele was present in approximately 40% of his sperm, 80% of his lymphocytes, and nearly 100% of his dermal fibroblasts. Despite the high level of mosaicism detected in somatic tissues, the only phenotypic manifestation of OI in the proband was that he was shorter than his unaffected male relatives and had mild dentinogenesis imperfecta. Thermal stability of type I collagen molecules containing the substitution was decreased, but to a lesser extent than for a nonlethal cysteine for glycine substitution at residue 259 of alpha 2(I), indicating that this measure of molecular stability may be of limited use in explaining the pathogenesis of osteogenesis imperfecta.
Adult↗
Mast cell degranulation inhibits IL-2-induced microvascular protein leakage.
The therapeutic efficacy of interleukin-2 (IL-2) in the treatment of cancer has been limited by a "vascular leak syndrome" and related toxicities. To better understand the pathophysiology of the "vascular leak syndrome," we tested a hypothesis that mast cell degranulation mediated the acute increase in microvascular protein leakage seen immediately following IL-2 administration. After the cremaster muscle was prepared for intravital microscopy, anesthetized Sprague-Dawley rats were injected with fluorescein isothiocyanate-labeled albumin for fluorescent microscopy. Animals were treated by the intravenous injection of IL-2 (1 x 10(6) U/kg) (n = 6), the control IL-2-vehicle (n = 5), or IL-2 (1 x 10(6) U/kg) after mast cell degranulation with compound 48/80 (n = 6). Relative interstitial fluorescent intensity was quantitated by a computerized image analysis system as an index of microvascular protein leakage. IL-2 acutely induced protein leakage from the microcirculation. Mast cell degranulation with 48/80 prior to IL-2 treatment prevented protein leakage, but did not alter IL-2-induced leukocyte-endothelial adherence. These data suggest that mast cell-mediated events may be responsible for the acute increase in microvascular permeability seen with IL-2 administration and that leukocyte-endothelial adherence alone is not solely responsible.
Animals↗
The induction of neural tube defects by maternal hyperthermia: a comparison of the guinea-pig and human.
In our recent studies on the effects of maternal hyperthermia on the embryonic guinea-pig, we have demonstrated two 'teratogenic windows' at embryonic days 13 and 21 (E13 and E21). E13 encompasses the period of the closure of the neural groove and anterior neuropore, and E21 the commencement of the cortical plate. The approximate equivalent developmental times in the human are E23-E25 and E49-E56 respectively. In the guinea-pig, maternal hyperthermia at E13 results in a high incidence of neural tube defects (NTD), many open, and associated with other defects such as microphthalmia, and scoliosis or kyphosis. The NTD were most common in the developing hindbrain and all demonstrated considerable infoldings of neural tissue, rosettes of neuroepithelial cells, outpocketings of neural tissue and large cystic cavities beneath the defect. In human examples from the Kyoto Human Embryo Collection, 16 had verified hyperthermic insults at E23-E25 and all had NTD which showed similar deformities to the guinea-pig. Most embryos with such gross defects are aborted in the early fetal period in both species.
Animals↗
Pentoxifylline inhibits interleukin-2-induced toxicity in C57BL/6 mice but preserves antitumor efficacy.
Interleukin 2 (IL-2) mediates the regression of metastatic cancer but clinical use has been limited due to associated toxicities. Tumor necrosis factor (TNF) is an important mediator of IL-2 toxicity and may have a limited role in IL-2 antitumor efficacy. Because pentoxifylline (PTXF) inhibits TNF production, we hypothesized that PTXF would ameliorate IL-2 toxicity without compromising antitumor efficacy. Four groups of female C57BL/6 mice with pulmonary metastases from a 3-methylcholanthrene-induced fibrosarcoma (MCA-105) and four groups of nontumored mice were treated every 6 h for 4 d by intraperitoneal injections of either IL-2 alone, IL-2 and PTXF, PTXF alone, or equal volumes of saline. Upon completion of therapy, we found that PTXF suppressed many of the IL-2-induced effects including TNF production, lymphocytic infiltration of multiple organs, multiple organ edema, hepatic dysfunction, leukopenia, and thrombocytopenia. Tumor response was determined 21 d after cessation of therapy by quantitating the number and surface area of pulmonary metastases. PTXF preserved antitumor efficacy while reducing the morbidity and mortality caused by IL-2 treatment. These data strongly support the use of PTXF in extending the therapeutic index of IL-2 in the treatment of cancer.
Animals↗
Deletion in blood mitochondrial DNA in Kearns-Sayre syndrome.
Mitochondrial DNA deletions have been described in the Kearns-Sayre syndrome (KSS) and the Pearson's marrow-pancreas syndrome. In some cases, the same 4,977-bp deletion has been identified in these two very different diseases. Therefore, it is not currently possible to predict the clinical phenotype from the size or location of the deletion. Instead, differential tissue distribution of the deletion has been implicated as one possible determinant of phenotype. In particular, in KSS the deletions have not been detected by Southern blotting in the blood, whereas in Pearson's syndrome they are easily detectable. We describe here an 11-y-old boy with clinically characteristic KSS and a 7.4-kb mitochondrial DNA deletion between nucleotides 7,194 and 14,595. Southern blotting reveals that 75% of the mitochondrial DNA molecules from his peripheral blood have this deletion. This case blurs further the molecular distinction between the KSS and Pearson's marrow-pancreas syndrome, questioning whether tissue distribution is a sufficient explanation for the very different phenotypes of these disorders.
Anemia, Sideroblastic↗
Passive immunization against tumor necrosis factor inhibits interleukin-2-induced microvascular alterations and reduces toxicity.
BACKGROUND: Antineoplastic therapy with interleukin-2 (IL-2) has been limited by dose-dependent systemic toxicities. Previous studies suggest that the hemodynamic instability and "vascular leak syndrome" that develop immediately after IL-2 administration occur secondary to neutrophil-mediated events in the microcirculation. Because IL-2 has limited direct effects on neutrophils and acutely induces the production of tumor necrosis factor-alpha (TNF), we hypothesized that the acute microvascular alterations and hemodynamic instability induced by IL-2 were mediated by TNF. METHODS: The cremaster muscles of anesthetized rats were prepared for intravital microscopy. All animals were injected with fluorescein isothiocyanate conjugated to bovine serum albumin, and relative interstitial fluorescence was quantitated as an index of macromolecular leakage. Vital signs, leukocyte-endothelial interactions, and interstitial fluorescence were quantitated every 30 minutes for 2 hours after intravenous injections of IL-2, TNF, and IL-2 with polyclonal antibody to TNF. RESULTS: Both IL-2 and TNF acutely induced hypotension, tachycardia, increased macromolecular leakage, and increased leukocyte-endothelial adherence. Polyclonal antibody to TNF effectively inhibited IL-2-induced leukocyte-endothelial adherence, macromolecular leakage, and hypotension. CONCLUSIONS: These data suggest that the acute microvascular alterations and hypotension induced by IL-2 are mediated by TNF.
Animals↗
Familial translocation 5;14 resulting in an unbalanced offspring.
We report on an infant with multiple congenital anomalies possessing a derivative 14 chromosome in excess of the normal complement, resulting from transmission of a familial t(5;14)(p13;q22). The proposita's phenotypically normal mother, mentally retarded half-brother, and fetal sib are carriers of the apparently balanced translocation. Previous cases of similar familial t(5;14) are reviewed. The proposita's phenotype is characterized by failure to thrive, developmental retardation, cleft palate, congenital heart anomaly, abnormal hands and feet, unusual face with abnormal ears, and recurrent respiratory infections. The proposita died at age 9 months and postmortem examination showed multiple central nervous system, cardiopulmonary, gastrointestinal, and genital malformations. Our proposita's phenotype is attributable to contributions from both chromosomes and is consistent with the consequences of both the dup(5p) and dup(14q).
Abnormalities, Multiple↗
Interleukin-2 acutely induces protein leakage from the microcirculation.
Interleukin-2 has been shown to mediate the regression of metastatic cancer. However, therapeutic application has been limited by the induction of dose-dependent toxicities in normal tissues secondary to a vascular leak syndrome. To better understand the pathophysiology of this vascular leak syndrome, the earliest microvascular effects of interleukin-2 were directly observed and quantitated by intravital microscopy. The cremaster muscle of anesthetized Sprague-Dawley rats was prepared for in vivo microvascular observation. Animals were injected with fluorescein isothiocyanate-labeled albumin, and the interstitial emission intensity was used to assess macromolecular leakage. Both the intravenous injection and topical application of interleukin-2 to the cremaster muscle acutely induced the leakage of macromolecules from the microcirculation. The topical application of interleukin-2 induced macromolecular leakage without changes in central hemodynamic parameters. Furthermore, topically applied interleukin-2 did not produce changes in arteriolar or venular diameters, or in regional microvascular blood flow, which could have influenced the protein leakage. These data support the hypothesis that the acute increase in macromolecular leakage produced by interleukin-2 occurs secondary to an increase in endothelial porosity and not as a result of changes in hemodynamic or hydrostatic forces.
Administration, Topical↗
Interference with neural crest migration by maternal hyperthermia as a cause of embryonic death due to heart failure.
Maternal hyperthermia has been demonstrated to be a teratogen in every animal species studied, and a minimum core temperature rise of 2.5 degrees C can produce a number of developmental defects. However, numerous embryos fail to survive to term. In the guinea-pig, heating the embryos prior to neural tube closure induces significant neural tube defects, but all embryos die within 20 days of heating. A number have aberrant cardiac development and many show spectacular pericardial effusions and congestion in the peripheral circulation. We suggest that maternal hyperthermia has interfered with neural crest migration which is a major component in the induction of these changes.
Animals↗
Mastectomy following preoperative chemotherapy. Strict operative criteria control operative morbidity.
The surgical morbidity associated with aggressive preoperative chemotherapy in 106 patients with advanced primary breast cancer who had chemotherapy followed by mastectomy was examined. These patients were compared with a group of 91 consecutive patients who had mastectomy without preoperative chemotherapy. Strict operative criteria were used to determine the timing of mastectomy following chemotherapy. Wound infection rates were no different in the preoperative chemotherapy group compared to the mastectomy-alone groups (7% versus 4%; p = 0.62). The incidence of wound necrosis was similar (11% versus 6%; p = 0.29). Seroma formation was decreased significantly in the preoperative chemotherapy group compared to the mastectomy-alone group (15% versus 28%; p = 0.04). Intensive preoperative chemotherapy did not delay the reinstitution of postoperative treatment (30% versus 20%; p = 0.27). However, when delay in instituting postoperative chemotherapy was more than 30 days, there was a significant decrease in overall survival rate (p = 0.04). This study provides evidence that intensive preoperative chemotherapy and mastectomy can be performed without increased morbidity. Furthermore it is important to institute systemic chemotherapy within 30 days of mastectomy to achieve maximum survival.
Adult↗
Heat shock proteins in cultured human keratinocytes and fibroblasts.
Heat shock induces in cells the synthesis of specific proteins called heat-shock proteins. We have compared the induction of these proteins in human keratinocytes, skin fibroblasts, and a human epithelial tumor cell line following exposure to weak and strong inducing agents (heat, cadmium sulphate, and sodium arsenite). The induction of heat shock proteins was measured in cells by one-dimensional gel electrophoresis of [35S] methionine-labeled proteins and by immunofluorescence using a specific HSP72 monoclonal antibody. Both HSP90 and HSP116 were constitutively expressed in these cell types. Exposure of these cells to weak inducing agents such as heat or cadmium sulphate resulted in the synthesis of HSP72 and HSP90, whereas HSP28 and HSP116 synthesis was detected in keratinocytes and fibroblasts following exposure to the strong inducing agent sodium arsenite. In addition, sodium arsenite induced the synthesis of HSP46 in human keratinocytes. Immunofluorescence demonstrated a rapid and reversible accumulation of the 72-kD heat shock protein within the nucleolus of heat-stressed human keratinocytes and fibroblasts.
Arsenic↗
Pentoxifylline inhibits interleukin-2-induced leukocyte-endothelial adherence and reduces systemic toxicity.
Interleukin-2 (IL-2) mediates the regression of metastatic cancer, but clinical application has been limited by the induction of dose-dependent toxicities in normal tissues. The most clinically significant toxicities occur secondary to a vascular leak syndrome and include acute respiratory failure and hemodynamic instability. Because previous studies suggested a role for pentoxifylline in attenuating the toxic effects of IL-2, we hypothesized that pentoxifylline would inhibit alterations in the microvasculature induced by IL-2 and would ultimately reduce IL-2-induced toxicity. To determine the validity of this hypothesis, we prepared four groups of rats for in vivo microvascular observation. In the first group, a bolus intravenous injection of IL-2 (1 x 10(6) units/kg) acutely induced hypotension, tachypnea, hypoxia, increased lung water, decreased microvascular blood flow, and increased leukocyte-endothelial adherence. No significant changes occurred in animals treated by pentoxifylline alone or the control IL-2 vehicle-alone group. However, pentoxifylline inhibited many of the IL-2-induced systemic and microvascular effects, such as hypotension, tachypnea, increased lung water, hypoxia, and increased leukocyte-endothelial adherence, but not tachycardia or increased microvascular protein leakage. These data support our hypothesis that systemic toxicities induced by IL-2 are associated with alterations in the microcirculation, which may be ameliorated by pentoxifylline.
Animals↗
Nursing research infrastructure present in Alberta acute care hospitals.
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Alberta↗
Isolated limb perfusion for localized melanoma of the extremity. A matched comparison of wide local excision with isolated limb perfusion and wide local excision alone.
The therapeutic efficacy of isolated limb perfusion in patients with localized melanoma of the extremity remains controversial. We compared patients treated at the University of Texas M.D. Anderson Cancer Center, Houston, with wide local excision and isolated limb perfusion using either melphalan or imidazole carboxamide with a group matched for prognostic factors from the University of Alabama at Birmingham and the University of Sydney (Australia) who were treated with wide local excision alone. No significant difference in disease-free or overall survival rates was found between patients treated with wide local excision with adjuvant isolated limb perfusion or wide local excision alone. However, a subset of patients with thicker lesions (greater than 2.0 mm) treated with wide local excision and isolated limb perfusion using melphalan had a significant improvement in both disease-free and overall survival rates. These data suggest that isolated limb perfusion using melphalan may improve survival rates in selected patients with localized melanoma of the extremity who are at increased risk for local and regional micrometastases, and justifies the continued study of this treatment approach in prospective clinical trials.
Aminoimidazole Carboxamide↗
Effects of pulsed ultrasound and temperature on the development of rat embryos in culture.
Rat embryos in culture were exposed to pulsed ultrasound at SPTA intensity of 1.2 W/cm2 for 5, 15, and 30 min on day 9.5 of development. The whole embryo culture system allowed precise temperature control for directly examining the effects of ultrasound on the developing neural plate. After exposure, embryos were maintained in culture for a further 48 hr. No major morphological abnormalities were observed but a reduction in somite number occurred in the group insonated for 30 min, which was equivalent to a 2 hr delay in embryonic development. Similar delay in growth and "blistering" in the prosencephalon region of some embryos were observed after insonation for 15 min at 40.0 degrees C, an elevation of 1.5 degrees C over the temperature used for controls. Exposure to ultrasound for 15 min at 40 degrees C caused significant reduction in the growth of the head compared with that of control embryos. Heat shock genes for hsps 71/73 and 88 kD were induced after insonation for 30 min at 38.5 degrees C. Insonation did not cause any temperature changes in the culture medium. However, when the temperature of the culture medium was increased during insonation, defective development occurred. The results of these in vitro experiments suggest that ultrasound if resulting in significant hyperthermia could affect the development during early organogenesis of the neural plate and in particular they suggest that the embryo is at greater risk of damage during hyperthermic conditions. These results should provoke discussion of the concept that ultrasound in the febrile patient may present an increased embryonic risk which should be considered when deliberating on the use of diagnostic ultrasound procedures in the pregnant patient.
Animals↗
Outpatient percutaneous central venous access in cancer patients.
A 1-year experience of percutaneous subclavian catheterization in outpatients with cancer was reviewed to document reliability, safety, and cost. There were 763 catheter insertions attempted with prospective documentation of complications in 664 consecutive patients. Catheter insertion was successful in 722 attempts (95%). There were only 13 pneumothoraces (2%). Thirty catheters required repositioning (4%). The average catheter duration was 191 days (range: 0 to 892 days). Fifty-six catheters (8%) were removed because of suspected infection. Documented catheter sepsis occurred in 21 patients (3%); catheter site infection occurred in 8 patients (1%). Thus, only 0.22 infections per catheter year occurred during this 382 catheter-year experience. The estimated cost of catheter insertion was $562, which is one-third the estimated cost for tunneled catheters ($1,403) and for reservoir devices ($1,738). In our experience, percutaneous subclavian catheterization is a reliable, cost-effective method compared with tunneled or reservoir devices, with an equivalent incidence of catheter-related infections. The cornerstone of our success with this program is a staff dedicated to catheter care and intensive patient education. In centers where a large number of patients require central venous access, percutaneous catheterization should be the technique of choice.
Ambulatory Care↗