Biomedical subjects
Publications and source records attributed to D H Johnson.
Infection is a well-described complication of cirrhosis and is a major cause of death in this population. This article examines the types of infections related with cirrhosis, such as bacteremia, urinary tract infections, meningitis, and others.
PURPOSE: To test the efficacy and safety of the novel antitumor agent MGI-114 (NSC 683863) in patients with advanced non-small cell lung cancer (NSCLC) previously treated with chemotherapy. METHODS: A two-stage accrual design was used to ensure detection of a true response rate of at least 20% with a type I error of .04. Eligible patients received 11 mg/m2 daily for five consecutive days. Cycles were repeated every 28 days. RESULTS: Fifteen patients received a total of 34 cycles of MGI-114. All patients had a performance status of 0 or 1. Eleven patients had previously received carboplatin and paclitaxel +/- radiation. Two patients had received cisplatin and CPT-11, one patient had received weekly paclitaxel, and one patient had received carboplatin and docetaxel. None of the first 15 patients enrolled experienced objective tumor response, and the study was closed. Forty percent of patients developed > or = grade 2 thrombocytopenia. Grade 3 nausea and > or = grade 2 vomiting were observed in 40% and 47% of patients respectively. Thirty-three percent of patients experienced > or = grade 2 fatigue. CONCLUSIONS: MGI-114, at this dose and schedule, does not have significant activity as second line therapy for patients with advanced NSCLC.
Six patients with incurable malignancies were originally treated with vitamin E, 3200 IU/day for fourteen days, followed by the same dose of vitamin E daily plus LCV (20 mg/m2 i.v. bolus daily x 5) with 5FU (425 mg/m2 i.v. bolus immediately following LCV). The same schedule of LCV and 5FU was repeated 4 weeks later, then every 5 weeks indefinitely. When 3 of the first 6 had grade 3/4 toxicity, six more patients were treated on the identical drugs and schedule. Seven of twelve total patients had one or more grade 3/4 toxicities. Neutropenia, abdominal pain, and diarrhea were most common. No patient had a documented response, though seven patients did have stable disease. Though the combination of vitamin E and chemotherapy was toxic, this trial demonstrated maximal therapeutic doses of vitamin E can be combined with standard 5FU and LCV, without significantly increasing the side effects of the chemotherapy itself.
PURPOSE: To determine whether the preservation of the extracellular matrix and the ultrastructural appearance of the trabecular meshwork are affected by different histologic processing protocols and embedding media. Conventionally used epoxy resins such as Araldite require complete dehydration of tissue, while the acrylic resin LR White requires only partial dehydration, better preserves tissue antigens, and has been reported to preserve more of the extracellular matrix. METHODS: Seven human eyes ranging in age from 2 months to 78 years were dissected and tissue samples from each eye processed and embedded in both Araldite and LR White media. The ultrastructure of the trabecular cells and the extracellular matrix of the meshwork was compared between media. The preservation of the extracellular matrix in the juxtacanalicular region was determined by measuring the amount of material immediately underlying Schlemm(1)s canal. Immunoelectron microscopy was used to determine the composition of this material. RESULTS: Araldite provided better resolution of ultrastructural details than freshly polymerized LR White. After a period of ripening for several months, however, resolution of tissue details in LR White improved. No significant quantitative difference was found in the amount of extracellular matrix underlying Schlemm's canal when comparing the two media. Neither post-mortem time to fixation (up to 31 hr), donor age, nor immersion vs. perfusion fixation technique affected the amount of extracellular material present in the comparison of the two embedding media. Immunogold labeling of the extracellular material within the juxtacanalicular tissue revealed the presence of collagen IV, laminin, and fibronectin in the basement membrane region immediately underlying the inner wall, and also in scattered patches within the juxtacanalicular tissue. CONCLUSIONS: Despite the less rigorous processing required for LR White than epoxy embedding, neither the appearance nor amount of the extracellular material was affected by the different embedding protocols. Prolonged post-mortem time to fixation did not affect the appearance nor amount of extracellular matrix. Immunolabeling revealed that the extracellular matrix of the juxtacanalicular tissue contains components of basement membrane material.
Several epithelial tumors display epidermal growth factor receptor (EGFR) overexpression (with or without EGFR gene amplification) that is often associated with increased production of EGFR ligands. This permits the activation of endogenous tumor EGFR via autocrine mechanisms, resulting in cellular proliferation and tumor growth. Interruption of receptor signaling with bivalent EGFR antibodies or with small molecule inhibitors of the EGFR tyrosine kinase results in inhibition of tumor cell proliferation or viability in vitro and in vivo. One small molecule currently undergoing preclinical and clinical investigation is ZD1839 (Iressa), a synthetic anilinoquinazoline capable of inhibiting EGFR tyrosine kinase in vitro. The early results of clinical trials indicate this drug possesses antitumor activity in certain malignancies of the upper aerodigestive tract.
Histologic, experimental, and theoretical studies of the aqueous outflow pathways point toward the juxtacanalicular region and inner wall of Schlemm's canal as the likely site of aqueous outflow resistance in the normal eye. At least 50% of the aqueous outflow resistance in the normal eye and the bulk of the pathologically increased resistance in the glaucomatous eye resides in the trabecular meshwork and the inner wall of Schlemm's canal. The uveoscleral, or uveovortex, pathway, which accounts for perhaps 10% of the aqueous drainage in the healthy aged human eye, can become a major accessory route for aqueous drainage after pharmacologic treatment. Surgeries designed to incise or remove the abnormal trabecular meshwork of glaucoma address the pathologic problem of the disease. Surgeries that unroof Schlemm's canal or expand the canal, such as viscocanalostomy, probably cause inadvertent ruptures of the inner wall and juxtacanalicular tissue, thus relieving the abnormal outflow resistance of glaucoma. This review is a summary of current thought on the pathophysiology of aqueous outflow resistance in glaucoma and, in light of this, provides an interpretation of the mechanism of pressure reduction created by these new surgeries.
PURPOSE: A quantitative study was conducted to estimate the survival time of giant vacuoles of the endothelial wall of Schlemm's canal once perfusion pressure has dropped to zero. Vacuoles are known to be sensitive to intraocular pressure and could serve as real-time markers of aqueous pressure in the juxtacanalicular tissue if their survival time is short once pressure is lowered. METHODS: Six pairs of healthy human eyes were perfused with phosphate-buffered saline. One eye was then fixed by perfusion, whereas the fellow eye was dissected into wedges and fixed by immersion at intervals ranging from 3 to 120 minutes after perfusion had been stopped. Light microscopy was used to determine the number of giant vacuoles on the inner and outer walls of Schlemm's canal. RESULTS: A 70% decrease in giant vacuole counts was found 3 minutes after discontinuation of saline perfusion when compared with perfusion-fixed fellow eyes (5.9 +/- 4.0 vacuoles per histologic section versus 19.1 +/- 9.0; P = 0.02). Vacuole counts continued to decrease with time so that by 120 minutes at zero pressure, vacuole counts were 12% of those in the perfusion-fixed eyes (88% decrease; P = 0.003). Giant vacuoles occurred on the inner and outer walls of the canal, but were more numerous on the inner wall. CONCLUSIONS: Most giant vacuoles have a short survival time, less than 3 minutes, once perfusion pressure decreases to zero. This suggests that they can respond rapidly to intraocular pressure changes and thus can serve as markers of aqueous pressure differences across the inner and outer walls of Schlemm's canal.
A recombinant live attenuated dengue virus type 4 (DEN4) vaccine candidate, 2ADelta30, was found previously to be generally well tolerated in humans, but a rash and an elevation of liver enzymes in the serum occurred in some vaccinees. 2ADelta30, a non-temperature-sensitive (non-ts) virus, contains a 30-nucleotide deletion (Delta30) in the 3' untranslated region (UTR) of the viral genome. In the present study, chemical mutagenesis of DEN4 was utilized to generate attenuating mutations which may be useful in further attenuation of the 2ADelta30 candidate vaccine. Wild-type DEN4 2A virus was grown in Vero cells in the presence of 5-fluorouracil, and a panel of 1,248 clones were isolated. Twenty ts mutant viruses were identified that were ts in both simian Vero and human liver HuH-7 cells (n = 13) or only in HuH-7 cells (n = 7). Each of the 20 ts mutant viruses possessed an attenuation phenotype, as indicated by restricted replication in the brains of 7-day-old mice. The complete nucleotide sequence of the 20 ts mutant viruses identified nucleotide substitutions in structural and nonstructural genes as well as in the 5' and 3' UTRs, with more than one change occurring, in general, per mutant virus. A ts mutation in the NS3 protein (nucleotide position 4995) was introduced into a recombinant DEN4 virus possessing the Delta30 deletion, thereby creating rDEN4Delta30-4995, a recombinant virus which is ts and more attenuated than rDEN4Delta30 virus in the brains of mice. We are assembling a menu of attenuating mutations that should be useful in generating satisfactorily attenuated recombinant dengue vaccine viruses and in increasing our understanding of the pathogenesis of dengue virus.
Antigen retrieval (AR) methods can unmask tissue antigens that have been altered by fixation, processing, storage, or resin interactions. This is particularly important in the study of archival tissues, because primary fixatives and storage times may vary among specimens. We performed an electron microscopic study of basement membrane components of the aqueous humor drainage pathways from archival eye tissue. AR (heated citrate buffer, pH 6.0, LR White resin) increased the amount of label of collagen IV and fibronectin in tissue fixed in four different fixatives, including those containing glutaraldehyde. Labeling density was approximately doubled after AR for most fixatives, with the largest increase for tissues fixed in 4% paraformaldehyde/2% glutaraldehyde. Duration of storage time for archival tissues did not affect AR results. AR did not change the components of the extracellular matrix labeled; no "new" components were labeled after AR. We conclude that AR in citrate buffer can be used on selected extracellular matrix antigens to enhance label that would otherwise be lost due to fixation and storage.
The combination of weekly irinotecan (CPT-11) and monthly cisplatin has shown promising activity in advanced non-small cell lung cancer (NSCLC) in previous Phase I and II studies. However, same-day administration of these agents may better exploit their therapeutic synergy and minimize toxicities. This multicenter Phase II study was undertaken to evaluate the efficacy and safety of a combination of weekly CPT-11 and weekly cisplatin in patients with advanced NSCLC. Patients with chemotherapy-naive stage IIIB or IV NSCLC were treated with repeated cycles of therapy comprising weekly treatment with both cisplatin and CPT-11 for 4 weeks, followed by a 2-week rest. The starting doses of CPT-11 and cisplatin were 65 and 30 mg/m2, respectively. Treatment was continued until the occurrence of disease progression, unacceptable toxicity, or a maximum of six cycles. Fifty patients were enrolled. The median age was 59 years (range, 44-79 years). Eastern Cooperative Oncology Group performance status was 0 in 22 patients, 1 in 19 patients, and 2 in 9 patients. Seven and 43 patients had stages IIIB and IV disease, respectively. Five patients had brain metastasis. Patients received a median of three 6-week cycles (range, 1-6). The objective response rate was 36% (18 of 50; 95% confidence interval, 24-54%) and included 18 partial responses. Median time to tumor progression was 6.9 months (range, 0.6-15.2). The median survival was 11.6 months (range, 0.16-21.9 months), and the 1-year survival rate was 46%. Grade 3/4 nonhematological toxicities included vomiting (12%) and diarrhea (26%). Grade 3/4 hematological toxicities included anemia (14%), neutropenia (26%), and thrombocytopenia (14%). Relative dose intensities for CPT-11 and cisplatin were 89 and 62%, respectively. Weekly combined administration of CPT-11 and cisplatin achieved a promising overall response rate, median time to tumor progression, and median survival in patients with stage IIIB/IV NSCLC. The regimen was well tolerated, and the planned dose intensity was well maintained. Further evaluation of this combination in NSCLC is warranted.
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The management of advanced NSCLC remains a daunting challenge; however, new tools are available for treating this malignancy, and continued progress is likely. The future is bright, with a myriad of opportunities to exploit our ever-expanding knowledge of tumor biology. What is perhaps most needed, however, is development of new methods to prevent children and young adults from ever taking up the use of tobacco. In addition, clinicians need new techniques to assist those who are already addicted to escape from tobacco's death grip. Sadly, most users of tobacco still fail to recognize the dangers of their habit. This needs to change.
Platinum-based chemotherapy regimens have been the mainstay of treatment for non-small-cell lung cancer because they improve survival. Although there is no standard platinum-based regimen, combination regimens with newer agents (e.g., gemcitabine [Gemzar], paclitaxel [Taxol], and vinorelbine [Navelbine]) are superior to platinum alone or in combination with older agents (e.g., etoposide). Four phase III clinical studies demonstrate the favorable activity and toxicity profile of gemcitabine in combination with cisplatin (Platinol) for the treatment of patients with stage IIIB or IV non-small-cell lung cancer. These studies show overall response rates of approximately 30% to 60% with gemcitabine regimens versus overall response rates of 11% with cisplatin alone, 22% with cisplatin plus etoposide, 25% with cisplatin plus vinorelbine, and 40% with cisplatin plus mitomycin and ifosfamide (Ifex). Median survival time with gemcitabine regimens ranged from 8.1 to 9.8 months. Thrombocytopenia and anemia are the principal toxicities with gemcitabine regimens. Because of the favorable results with gemcitabine regimens, this drug is being evaluated in combination with carboplatin (Paraplatin) in newly diagnosed patients with stage IIIB or IV disease and good performance status, or as single-agent therapy in patients with poor performance status.
PURPOSE: To determine whether myocilin (MYOC; also referred to as TIGR) is present as a complex in human aqueous humor, whether part of the complex formation may be due to MYOC-MYOC interactions and to characterize the sites of interaction. METHODS: Human aqueous humor was analyzed by using a gel filtration column for the identification of MYOC complexes. MYOC-MYOC interactions were studied with a yeast two-hybrid system. Expression of full-length and truncated MYOC proteins in AH109 yeast was analyzed for growth and color on minimal medium. Site-directed mutagenesis was used to selectively mutate eight leucine residues within the leucine zipper motif. In vitro transcription and translation was used to verify yeast two-hybrid analysis. RESULTS: MYOC was found to be present in human aqueous humor as a complex ranging from 120 to 180 kDa. Expression of full-length MYOC in yeast as well as in vitro binding studies revealed that MYOC can interact with itself. MYOC-MYOC interactions occurred mainly within amino acids 117-166, a region containing a leucine zipper domain. Glycine substitution for selective leucine residues confirmed that MYOC-MYOC interactions occurred mainly within the leucine zipper domain. CONCLUSIONS: MYOC is present in human aqueous humor, not as a monomer but as a complex. Part of this complex may form due to MYOC-MYOC interactions that take place mainly within the leucine zipper domain.
BACKGROUND: Elderly patients comprise a significant portion of patients with limited stage small cell lung carcinoma. However, the prognostic importance of age has been controversial, and concern for toxicity often hinders enthusiasm for offering full dose therapy. METHODS: In this retrospective analysis of Intergroup Trial 0096, the authors compared the outcome of patients 70 years or older to those younger than 70 years. Patients received cisplatin 60 mg/m(2), Day 1 and etoposide 120 mg/m(2), Days 1-3 for 4 cycles and either once or twice daily concurrent thoracic radiotherapy to 45 grays. RESULTS: Of 381 patients, 50 (13%) were age 70 years or older. The elderly group did not differ significantly from those younger than 70 years with respect to gender distribution, performance status, or weight loss. Severe hematologic toxicity (Grade 4-5: 61% vs. 84%; P < 0.01) and fatal toxicity (1% vs. 10%; P = 0.01) occurred more often among older patients. There were no differences in the frequency of nonhematologic toxicities. Response rate (88% vs. 80%; P = 0.11), event free survival rate (5 year, 19% vs. 16%; P = 0.18), time to local failure, and duration of response did not differ between groups. Overall survival rates (5 year, 22% vs. 16%; P = 0.05) favored those younger than 70 years. Much of the difference in overall survival rates between age groups occurred within the first 6 months on study. CONCLUSIONS: Elderly patients had similar response and survival rates compared with those younger than 70 years. However, toxicity, particularly hematologic, was greater among the elderly. Selected older patients, such as those with a good performance status, should be considered for optimum treatment approaches.
BACKGROUND: We conducted a randomized trial to determine whether combination chemotherapy plus thoracic radiotherapy is superior to thoracic radiotherapy alone in prolonging survival and preventing local recurrence in patients with completely resected stage II or IIIa non-small-cell lung cancer. METHODS: After surgical staging and resection of the tumor (usually by lobectomy or pneumonectomy), the patients were randomly assigned to receive either four 28-day cycles of cisplatin (60 mg per square meter of body-surface area intravenously on day 1) and etoposide (120 mg per square meter intravenously on days 1, 2, and 3) administered concurrently with radiotherapy (a total of 50.4 Gy, given in 28 daily fractions) or radiotherapy alone (a total of 50.4 Gy, given in 28 daily fractions). RESULTS: Of the 488 patients who were enrolled in the study, 242 were assigned to receive radiotherapy alone and 246 were assigned to receive chemotherapy and radiotherapy. The median duration of follow-up was 44 months. Treatment-associated mortality was 1.2 percent in the group given radiotherapy alone and 1.6 percent in the group given chemotherapy and radiotherapy. The median survival was 39 months in the group given radiotherapy and 38 months in the group given chemotherapy and radiotherapy (P= 0.56 by the log-rank test). The relative likelihood of survival among patients assigned to receive chemotherapy and radiotherapy, as compared with those assigned to receive radiotherapy alone, was 0.93 (95 percent confidence interval, 0.74 to 1.18). Intrathoracic disease recurred within the radiation field in 30 of 234 patients (13 percent) in the group given radiotherapy and in 28 of 236 patients (12 percent) in the group given chemotherapy and radiotherapy (P=0.84); data on recurrence were not available for 18 patients. CONCLUSIONS: As compared with radiotherapy alone, adjuvant radiotherapy and chemotherapy with cisplatin and etoposide does not decrease the risk of intrathoracic recurrence or prolong survival in patients with completely resected stage II or IIIa non-small-cell lung cancer.
PURPOSE: We conducted a prospective phase II study to determine the response rate, toxicity, and survival rate of concurrent weekly paclitaxel, carboplatin, and hyperfractionated radiation therapy (paclitaxel/carboplatin/HFX RT) followed by 2 cycles of paclitaxel and carboplatin for locally advanced unresectable non-small cell lung cancer (NSCLC). The weekly paclitaxel and carboplatin regimen was designed to optimize the radiosensitizing properties of paclitaxel during the concurrent phase of treatment. METHODS AND MATERIALS: Forty-three patients with unresectable stage IIIA and IIIB NSCLC from the Vanderbilt Cancer Center and Affiliate Network (VCCAN) institutions were entered onto the study from June 1996 until May 1997. Weekly intravenous (IV) paclitaxel (50 mg/m(2)/l-hour) and weekly carboplatin (AUC 2) plus concurrent hyperfractionated chest RT (1.2 Gy/BID/69.6 Gy) were delivered for 6 weeks followed by 2 cycles of paclitaxel (200 mg/m(2)) and carboplatin (AUC 6). RESULTS: Forty-two patients were evaluable for response and toxicities. Three patients achieved a complete response (7.2%) and 30 patients achieved a partial response (71.4%), for an overall response rate of 78.6% [95% C.I. (66.2%-91.0%)]. The 1- and 2-year overall and progression-free survival rates of all 43 patients were 61.6% and 35% respectively, with a median survival time of 14.3 months. The median follow-up time was 14 months. Esophagitis was the principal toxicity. Grade 3 or 4 esophagitis occurred in 11 patients (26%). There was an incidence of 7% grade 3 and 9.5% grade 4 pulmonary toxicities. CONCLUSIONS: Weekly paclitaxel, carboplatin, plus concurrent hyperfractionated RT is a well-tolerated outpatient regimen. The response rate from this regimen is encouraging and appears to be at least equivalent to the more toxic chemoradiation trials. These findings warrant further clinical evaluation of weekly paclitaxel/carboplatin/HFX RT in a phase III study.
BACKGROUND: Nonsmall cell lung carcinoma comprises approximately 75% of all lung carcinoma cases in the U.S. Newly evolving strategies have created considerable controversy regarding the optimal treatment for patients diagnosed with this disease. METHODS: A 17-item survey was designed to collect demographic data and information regarding practice patterns for nonsmall cell lung carcinoma, including patient assessment, treatment approaches, and roles of chemotherapy and radiotherapy. Surveys were mailed in the summer of 1997 to approximately 9200 oncologists of all types throughout the U.S. Practice settings included private office, private hospital, academic, university-affiliated office, government, and Veterans Administration institutions. RESULTS: Approximately 10% of the oncologists responded (n = 979), including 499 medical oncologists (51%), 464 radiation oncologists (47%), and 16 others (2%). For the adjuvant treatment of surgically resected N1-2 disease, combined modality treatment was preferred over radiation therapy alone by medical oncologists (48% vs. 16%; P<0.001) and radiation therapy alone was preferred over combined modality treatment by radiation oncologists (55% vs. 38%; P<0.001). The combination of paclitaxel and carboplatin was the preferred first-line regimen for all stages of nonsmall cell lung carcinoma by the majority of medical oncologists (55%), whereas the majority of radiation oncologists (58%) chose the combination of etoposide and platinum. With regard to the optimal combined modality approach, respondents were divided evenly between concurrent chemoradiotherapy (34%) and sequential chemoradiotherapy (31%). Overall, respondents reported basing treatment decisions largely on published literature (55%) compared with personal experience (19%), seminars and colleagues (16%), and clinical trial availability (10%) (P<0.001). CONCLUSIONS: This survey confirms many differences in practice patterns among medical oncologists and radiation oncologists in the treatment of patients with nonsmall cell lung carcinoma and suggests the need for the multidisciplinary management of this entity. In addition, the current study demonstrates that reliance on the medical literature as a basis for treatment steadily declines the longer the physician has been in practice.