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Biomedical subjects

D H Johnson

Publications and source records attributed to D H Johnson.

At least 19 recordsLinked to original sources
PubMed1992

A meta-analysis of thoracic radiotherapy for small-cell lung cancer.

BACKGROUND: In spite of 16 randomized trials conducted during the past 15 years, the effect of thoracic radiotherapy on the survival of patients with limited small-cell lung cancer remains controversial. The majority of these trials did not have enough statistical power to detect a difference in survival of 5 to 10 percent at five years. This meta-analysis was designed to evaluate the hypothesis that thoracic radiotherapy contributes to a moderate increase in overall survival in limited small-cell lung cancer. METHODS: We collected individual data on all patients enrolled before December 1988 in randomized trials comparing chemotherapy alone with chemotherapy combined with thoracic radiotherapy. Trials that included only patients with extensive disease were excluded. RESULTS: The meta-analysis included 13 trials and 2140 patients with limited disease. A total of 433 patients with extensive disease were excluded. Overall, 1862 of 2103 patients who could be evaluated died; the median follow-up period for the surviving patients was 43 months. The relative risk of death in the combined-therapy group as compared with the chemotherapy group was 0.86 (95 percent confidence interval, 0.78 to 0.94; P = 0.001), corresponding to a 14 percent reduction in the mortality rate. The benefit in terms of overall survival at three years (+/- SD) was 5.4 +/- 1.4 percent. Indirect comparison of early with late radiotherapy and of sequential with non-sequential radiotherapy did not reveal any optimal time for treatment. There was a trend toward a larger reduction in mortality among younger patients: the relative risk of death in the combined-therapy as compared with the chemotherapy group ranged from 0.72 for patients less than 55 years old (95 percent confidence interval, 0.56 to 0.93) to 1.07 (0.70 to 1.64) for patients over 70. CONCLUSIONS: Thoracic radiotherapy moderately improves survival in patients with limited small-cell lung cancer who are treated with combination chemotherapy. Identification of the optimal combination of chemotherapy and radiotherapy will require further trials.

Age Factors↗
PubMed1992

A phase II trial of cisplatin and prolonged administration of oral etoposide in extensive-stage small cell lung cancer.

Etoposide is a schedule-dependent agent with greater activity against small cell lung cancer (SCLC) when a given dose is administered over several days compared with a 1-day administration of the same dose. In an attempt to capitalize on the schedule dependency of etoposide, 22 previously untreated extensive-stage SCLC patients were given cisplatin (100 mg/m2 on day 1) plus 21 days of low-dose, oral etoposide (50 mg/m2/d). Chemotherapy was repeated every 28 days for four cycles. Complete blood counts were monitored weekly, and etoposide was discontinued if either the leukocyte or platelet count dropped below 2000/microliters or 75,000/microliters, respectively. All 22 patients were evaluable for response; 18 had either a complete (9%) or partial response (73%), an overall response rate of 82% (95% confidence interval, 62% to 93%). The median response duration was 7 months, and the median survival was 9.9 months (range, 1 to 17+ months). Sixteen (73%) patients received all planned cycles of etoposide. In Cycle 1 of chemotherapy, the median leukocyte nadir was 2700/microliters (range, 100 to 6300/microliters), and median platelet nadir was 180,000/microliters (range, 51,000 to 397,000/microliters). Life-threatening leukopenia (less than 1000/microliters) was rare (3 of 74 cycles). There were three treatment-related deaths, only one of which was associated with neutropenia. One patient had mild renal insufficiency that resolved after discontinuation of therapy. Alopecia was observed in all patients, but other nonhematologic toxicities were uncommon. A randomized study is necessary to determine if this schedule of cisplatin and etoposide administration is superior to more standard methods. However, these data do not indicate a major survival benefit will be derived from increasing the duration of etoposide administration when used in combination with cisplatin given every 28 days.

Administration, Oral↗
PubMed1992

Changes in PETCO2 and pulmonary blood flow after bronchial occlusion in dogs.

The use of PETCO2 in detecting accidental bronchial intubation was investigated. The PETCO2 was measured in six mongrel dogs after occluding the left mainstem bronchus in three conditions; pentobarbital anaesthesia, 0.8% halothane insufflation together with pentobarbital anaesthesia, and simultaneous left pulmonary artery and bronchial airway occlusion with intravenous pentobarbital anaesthesia. An external flow probe measured left pulmonary artery blood flow. The PETCO2 decreased after bronchial occlusion during pentobarbital (35 +/- 3 vs 30 +/- 5 mmHg) and halothane-pentobarbital (30 +/- 6 vs 25 +/- 6 mmHg) conditions (P less than 0.05). However, within three minutes of bronchial occlusion, the values of PETCO2 had returned to their pre-occlusion values. After five minutes of bronchial occlusion pulmonary artery blood flow in the non-ventilated lung decreased (P less than 0.05) during pentobarbital (770 +/- 533 ml.min-1 vs 575 +/- 306 ml.min-1) and halothane-pentobarbital (495 +/- 127 ml.min-1 vs 387 +/- 178 ml.min-1) conditions. Simultaneous bronchial and pulmonary artery occlusion prevented any changes in PETCO2. It was concluded that accidental one-lung ventilation results in small and transient decreases in PETCO2. A redistribution of blood flow from the non-ventilated to ventilated lung occurs which restores PETCO2 to the original values observed with two-lung ventilation.

Airway Obstruction↗
PubMed1992

Function-based modeling of binaural processing: interaural phase.

The intent of function-based modeling is to predict from theoretical considerations the input/output characteristics of a neuron if it were to perform a specific signal processing task within a sensory system. In this study, the sensory task is localization within the horizontal plane of a sustained low-frequency tone using interaural phase cues alone. The stimulus is assumed to be represented by primary-like discharge patterns from each ear. These patterns serve as the input to a system whose task is to extract the information needed to determine azimuthal angle. The optimal system resembles the classic Jeffress model, but differs from it in important details. In particular, the Jeffress model is shown to be a sub-optimal approximation in that it ignores the characteristic frequency of the inputs. The physical realization of either model by a structure resembling currently known MSO anatomy and innervation is discussed.

Acoustic Stimulation↗
PubMed1992

Excitatory/inhibitory interaction in the LSO revealed by point process modeling.

We studied lateral superior olivary (LSO) unit responses to binaural tone-bursts using a general point process approach. We show that inhibition of the ipsilaterally elicited response by contralateral stimulation cannot be modeled simply as a reduction of the ipsilateral input. Statistical analyses reveal that inhibition operates by scaling the intensity of the point process describing the ipsilateral response. In some cases the scaling process has secondary effects: Binaurally elicited discharges produce bimodal interspike interval histograms from units that produce unimodal interval histograms under monaural stimulation. We present a specific point process model that describes the scaling process and successfully replicates the observed responses to monaural and binaural stimulation of the three types of LSO units: slow choppers, fast choppers, and bimodal units. We interpret scaling as a shunting inhibitory process in these LSO neurons. By relating scaling magnitude to interaural level difference, we demonstrate the spatial sensitivity of LSO units.

Acoustic Stimulation↗
PubMed1992

Microdissection of a human marker chromosome reveals its origin and a new family of centromeric repetitive DNA.

A series of procedures including chromosome microdissection, sequence-independent PCR, Southern-blot-hybrid-selection-cloning and sequencing of microdissected DNA-library members were used to analyze DNA from a familial marker chromosome centromere and to determine the origin of the marker chromosome in the case of a live-born, tetraploid human infant. A new family of repetitive DNA, termed sn5 satellite, was sequenced and characterized by DNA hybridization. The sn5 satellite family appears to be primate-specific and shows a chromosome-specific distribution which parallels that of alpha satellite suprachromosomal family 2. This suprachromosomal classification is based on sequence similarity of centromeric alpha satellite DNA within particular groups of chromosomes. It has been postulated that the similarity of alphoid sequences within each of the three suprachromosomal families results from homologous exchanges between nonhomologous chromosomes within each family. The parallel distribution of sn5 satellite sequences at the centromeres of chromosomes of alphoid suprachromosomal family 2 suggests that homologous exchanges between non-homologous chromosomes may be the basis of simultaneous chromosome-specific sequence conservation for multiple centromeric satellite DNA families.

Base Sequence↗
PubMed1992

Staging lung carcinoma with a Tc-99m labeled monoclonal antibody.

Thirty-three patients with biopsy-proven lung cancer and a total of 150 lesions diagnosed by conventional staging procedures were imaged using a Tc-99m labeled monoclonal Fab fragment of an IgG2B murine monoclonal antibody (MoAb) (NR-LU-10, NeoRx Corporation). Immunoscintigraphy demonstrated 100% of primary and 78% of metastatic lesions. MoAb imaging detected 88% of lesions in 12 small cell lung cancer (SCLC) patients and 77% of lesions in 21 non-small cell lung cancer (NSCLC) patients. Based on initial evaluation by other methods, 29 sites of MoAb activity were not associated with evidence of disease. Eleven of these were subsequently shown to represent sites of metastases; 18 remain unconfirmed. Four of ten patients studied with limited NSCLC had eight unsuspected lesions on MoAb imaging. Confirmation of unsuspected lesions in two patients altered initial clinical staging, and surgical therapy was abandoned. This study demonstrates that Tc-99m labeled NR-LU-10 can accurately stage patients with lung cancer.

Carcinoma, Non-Small-Cell Lung↗
PubMed1992

Prolonged administration of oral etoposide plus cisplatin in extensive stage small cell lung cancer.

Etoposide is a highly schedule-dependent agent. We previously reported that a 21-day schedule of oral etoposide had good activity in small cell lung cancer (SCLC). The current phase II study was designed to test the combination of 21-day oral etoposide with cisplatin in hopes of capitalizing on etoposide's schedule dependency. Sixteen extensive stage SCLC patients were treated with cisplatin 100 mg/m2 day 1 plus 21 days of low-dose oral etoposide 50 mg/m2/day. Chemotherapy was repeated every 28 days for 4 cycles. Blood counts were monitored weekly, and etoposide was discontinued if the leukocyte or platelet count dropped below 2.0 x 10(9)/l or 75 x 10(9)/l, respectively. Fifteen of 16 patients were evaluable for response; 13 achieved either a complete (13%) or partial response (73%), for an overall response rate of 86% (95% confidence interval, 62-93%). Median response duration was approximately 7 months; median survival was not reached. Thirteen patients (81%) received all the planned cycles of chemotherapy. In cycle 1 of chemotherapy, the median leukocyte nadir was 2.8 x 10(9)/l (range, 0.1-6.3 x 10(9)/l; median platelet nadir was 180 x 10(9)/l (range, 51-397 x 10(9)/l). Life-threatening leukopenia (less than 1.0 x 10(9)/l) was unusual (2 of 58 cycles). There was 1 treatment-related death. One patient developed mild renal insufficiency that resolved after therapy. Nonhematologic toxicities were uncommon, but alopecia occurred in all patients. These data do not suggest that a major survival benefit will be derived for patients with extensive stage SCLC by increasing the duration of etoposide administration when used in combination with cisplatin. A randomized study is needed to determine if this long-term schedule of etoposide plus cisplatin is superior to the standard schedule of etoposide plus cisplatin.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Carboplatin plus oral etoposide in the management of unresectable non-small cell lung cancer. Preliminary results of a Vanderbilt trial.

Forty-two patients with unresectable non-small cell lung cancer (NSCLC) were treated with carboplatin (300, 350 or 400 mg/m2) and 21 days of oral etoposide (50 mg/m2/day). Thirty-three patients were evaluable for response (too early to assess the remaining patients) and 9 patients (27%) achieved a partial remission. Median survival was 29 weeks (range, 4+ to 71+ weeks). The primary toxicity was myelosuppression. Leukocyte and platelet count nadirs occurred between days 22 and 29. In cycle 1, median leukocyte nadir was 2.8 x 10(9)/l and the platelet nadir was 142 x 10(9)/l. Nonhematologic toxicities were modest and included alopecia in all patients, mild nausea, mild to moderate diarrhea, and an occasional increase in serum creatinine. Carboplatin plus oral etoposide is a tolerable outpatient regimen with modest activity against unresectable NSCLC.

Administration, Oral↗
PubMed1992

Randomized study of cyclophosphamide, doxorubicin, and vincristine versus etoposide and cisplatin versus alternation of these two regimens in extensive small-cell lung cancer: a phase III trial of the Southeastern Cancer Study Group.

PURPOSE: The trial was undertaken to determine (1) the relative efficacy/toxicity of two commonly used combination chemotherapy regimens in patients with extensive small-cell lung cancer (SCLC) and (2) whether the rapid alternation of these two regimens could provide superior therapeutic results compared with either regimen alone. PATIENTS AND METHODS: In this phase III trial, 437 eligible patients were stratified by performance status (PS) and sex and were randomly assigned to receive either 12 weeks of cisplatin and etoposide (EP); 18 weeks of cyclophosphamide, doxorubicin, and vincristine (CAV); or 18 weeks of alternation of these two regimens (CAV/EP). RESULTS: There were no significant differences in treatment outcome for EP, CAV, or CAV/EP in terms of response rate (61%, 51%, 59%, respectively), complete response rate (10%, 7%, 7%, respectively), or median survival (8.6 months, 8.3 months, 8.1 months, respectively), with a non-statistically significant trend toward a longer median time to progression with alternating therapy (4.3 months, 4.0 months, 5.2 months, respectively). Crossover second-line chemotherapy given at progression produced low response rates and short survival, regardless of the regimen used. Myelosuppression was the dose-limiting toxicity for all patients, although the pattern and severity differed among the treatment arms. CONCLUSIONS: The combination regimens EP and CAV can be considered equivalently effective induction therapies in extensive SCLC, and these two regimens are, to some degree, crossresistant. Alternating therapy provides no therapeutic advantage compared with the use of either of these regimens alone and should not be considered as standard treatment in this clinical setting.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Prolonged administration of oral etoposide in non-small-cell lung cancer: a phase II trial.

PURPOSE: The trial was undertaken to investigate the activity and toxicity of a prolonged schedule of oral etoposide in the treatment of advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Between March 1989 and August 1990, 25 patients with advanced NSCLC were treated with oral etoposide 50 mg/m2/d for 21 consecutive days, repeated every 28 to 35 days. The median patient age was 60 years (range, 38 to 84 years); male:female ratio was 12:13. Eight patients had stage IIIB disease; 17 had stage IV. Seventy-six percent of patients had Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. No patient had received previous chemotherapy with standard agents; nine patients had received previous or concurrent radiation therapy. Plasma etoposide concentrations were measured to estimate etoposide bioavailability and kinetics. RESULTS: Five of 22 patients (23%; 95% confidence interval [CI], 10% to 43%) had partial responses. Median response duration was 5 months (range, 2 to 6 months). Four of five responders were female. Besides alopecia, which occurred in all patients, myelosuppression was the most common toxicity, but was mild or moderate in most patients. Median leukocyte nadir during course 1 was 3,200/microL; only four of 69 courses produced a leukocyte nadir less than 1,000/microL. Severe thrombocythemia (less than 75,000/microL) did not occur. Gastrointestinal toxicity was uncommon. Median peak etoposide concentration was 3.4 micrograms/mL. A mean serum etoposide concentration greater than 1 microgram/L was maintained for more than 13 hours; the plasma concentration-time curve (AUC) was estimated to be 90% of that predicted after an identical dose of etoposide given intravenously. CONCLUSIONS: Etoposide given by this dose and schedule has moderate activity as first-line systemic therapy for advanced NSCLC. In previously untreated patients, chronic oral etoposide is well tolerated, and incorporation into combination regimens should be feasible. Etoposide bioavailability may be increased at lower oral doses.

Administration, Oral↗
PubMed1992

Cisplatin-based combination chemotherapy in the treatment of poorly differentiated carcinoma and poorly differentiated adenocarcinoma of unknown primary site: results of a 12-year experience.

PURPOSE: We previously reported excellent responses to cisplatin-based chemotherapy in a minority of patients with poorly differentiated carcinoma (PDC) or poorly differentiated adenocarcinoma (PDA) of unknown primary site. We have continued to study and to treat these patients, and now report clinical characteristics, treatment results, and prognostic factors in a large group of patients identified prospectively. PATIENTS AND METHODS: Between February 1978 and December 1989, we treated 220 patients with PDC or PDA of unknown primary site. The median age was 39 years; 48% of patients had predominant tumor location in the mediastinum, retroperitoneum, or peripheral lymph nodes. Specialized pathologic studies resulted in the identification of specific tumor types in only a few cases. All patients received cisplatin-based chemotherapy; between 1978 and 1984, 116 patients received cisplatin, vinblastine, and bleomycin (PVeB) +/- doxorubicin, and 104 patients treated since January 1985 received cisplatin and etoposide +/- bleomycin. RESULTS: One hundred thirty-eight patients (63%) had objective responses to therapy, and 58 (26%) had complete response. Thirty-six patients (16%) are currently disease-free at a median of 61 months following therapy (range, 11 to 142 months). Actuarial 10-year survival is 16%. Favorable prognostic factors identified by Cox regression analysis include: (1) predominant tumor location in the retroperitoneum or peripheral lymph nodes, (2) tumor limited to one or two metastatic sites, (3) no history of cigarette use, and (4) younger age. CONCLUSION: Patients with PDC or PDA of unknown primary site represent another group of patients for whom potentially curative therapy is available. Patients with this syndrome should be distinguished from patients with well-differentiated adenocarcinoma of unknown primary site, and should receive a trial of cisplatin-based chemotherapy.

Adenocarcinoma↗
PubMed1992

Factors influencing in vivo trabecular cell replication as determined by 3H-thymidine labelling; an autoradiographic study in cats.

Because trabecular cell loss is thought to play a role in the pathogenesis of some forms of glaucoma, identification of factors which influence trabecular cell division may provide some insight into the mechanisms and potential treatment of this disease. We studied several commonly encountered clinical situations which may affect the trabecular meshwork: phagocytosis of debris, hyphema, and argon laser trabeculoplasty. The effect of these factors on trabecular cell division was determined using 3H-thymidine autoradiography. Laser trabeculoplasty induced a 307% increase in 3H-thymidine labelling of trabecular cells while phagocytosis and hyphema had no effect on cell labelling. In addition, subgroups of eyes with a loss of trabecular cells or with inflammation did not have increased labelling. Thus laser trabeculoplasty, known to increase outflow facility, was associated with increased trabecular cell labelling while factors often associated with decreased outflow facility and glaucoma were not.

Animals↗
PubMed1992

Carboplatin plus oral etoposide in the management of advanced, non-small cell lung cancer: preliminary results of a Vanderbilt trial.

Twenty-eight patients with unresectable, metastatic non-small cell lung cancer (NSCLC) were treated with carboplatin/oral etoposide. Carboplatin was administered intravenously on day 1 at a dose of 300 mg/m2 (12 patients) or 350 mg/m2 (16 patients); oral etoposide was administered at a dose of 50 mg/m2/d for 21 consecutive days. Treatment was repeated every 28 days. Patient characteristics included male:female ratio of 23:5, median age of 60 years, median Eastern Cooperative Oncology Group performance status of 1, weight loss of 5% or more in seven patients; stage IIIB disease in two patients and stage IV in 26. Twenty-five patients were evaluable for response and seven (28%) achieved a partial response (95% confidence interval, 14% to 48%). Median duration of response was 3+ months (range, 2+ to 6+) and median survival was 4+ months (range, 1+ to 10+). Myelosuppression was the predominate toxicity; leukocyte and platelet nadirs occurred between days 22 and 29, with median counts of 2,900/microL and 172,000/microL, respectively. The median interval between the start of cycle 1 and the start of cycle 2 was 33 days (range, 26 to 42). Carboplatin/oral etoposide is a moderately active regimen against advanced NSCLC that can be administered in an outpatient setting with manageable toxicity. Its impact on survival remains to be determined.

Administration, Oral↗
PubMed1992

Combination chemotherapy with oral etoposide.

Chronic administration of etoposide over multiple days has proved to be an effective schedule against a variety of neoplasms. The usual duration of etoposide administration is 3 to 5 days. However, recent studies have demonstrated this agent can be administered for up to 21 consecutive days with acceptable toxicity. Studies are currently under way to determine whether more protracted etoposide administration will prove to be more efficacious in the management of selected malignancies. Previous work at our institution has confirmed the activity of protracted administration of single-agent etoposide against small cell lung cancer and non-small cell lung cancer. More recently, we have combined either cisplatin or carboplatin with etoposide given orally for 21 consecutive days in phase II trials in patients with small cell lung cancer and non-small cell lung cancer. The results of these trials are reviewed.

Administration, Oral↗
PubMed1992

The role of cisplatin/bleomycin-based chemotherapy in the treatment of poorly differentiated carcinoma of unknown primary site.

Between 1978 and 1990, 173 patients with poorly differentiated carcinoma or poorly differentiated adenocarcinoma of unknown primary site were treated with bleomycin-containing regimens at Vanderbilt University Medical Center. Patients were prospectively identified based on light microscopy findings. The median age of patients was 39 years; 78% were male and 76% had metastatic tumors in two or more sites. Dominant tumor location was the mediastinum, retroperitoneum, or peripheral lymph nodes in 82 patients (47%). Between 1978 and 1985, patients received cisplatin 20 mg/m2 intravenously (IV) days 1 through 5, vinblastine 0.15 mg/kg IV days 1 and 2, and bleomycin 30 U IV weekly. In 1986, etoposide 100 mg/m2 IV days 1 through 5 replaced vinblastine in the regimen. Responding patients received four courses of therapy at 3-week intervals. One hundred thirteen patients (65%) had a major response to therapy, including 47 (27%) complete responses. At present, 27 patients are disease free at a median of 78 months posttherapy (range, 11 to 142 months); an additional patient was lost to follow-up while in complete response. Median survival of the entire group was 11 months, with a 12-year actuarial disease-free survival of 16%. Combination chemotherapy with cisplatin/bleomycin and either vinblastine or etoposide is highly active in patients with poorly differentiated carcinoma of unknown primary site and is curative in a minority of these patients. A trial of this therapy should be considered in all such patients.

Adenocarcinoma↗