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Biomedical subjects

D M Green

Publications and source records attributed to D M Green.

At least 109 records · Page 6Linked to original sources
PubMed1995

Effect of signal component phase on asynchrony discrimination.

The ability of listeners to detect the temporal asynchrony of a single harmonic in complex sounds was measured. The listeners discriminated an asynchronous complex from one in which all harmonics were synchronous (standard). The asynchrony was created either at the onset or offset of the complex. In the asynchronous complex, one component either began or ended after all other components in the complex, or it began or ended prior to all other components in the complex. The phase of the signal component was systematically varied in the range from 0 degrees to 180 degrees. All nonsignal components had the same sine phase. The results show that detecting the asynchrony at the onset is superior when all components are in sine phase. Altering the phase of the signal component increased thresholds by as much as a factor of 50, with the largest thresholds obtained when the signal component was inverted in phase. For offset conditions, the phase of the signal component had a much smaller and less consistent effect. Some of the observed effects of phase on the asynchrony thresholds can be understood by considering the response of the Roex filter [Patterson et al., J. Acoust. Soc. Am. 72, 1788-1803 (1982)] centered at the signal frequency.

Auditory Perception↗
PubMed1995

Reliability of pure-tone thresholds at high frequencies.

Standing waves, in the ear canal are created by the interference of two plane waves of the same frequency traveling in opposite directions. One manifestation of this phenomena is that any lateral motion of the transducer produces a change in the length of the canal and therefore, in general, a change in the sound level at the eardrum. Because of the smaller wavelength at the higher frequencies, the changes produced by movement of the transducer will be larger for the higher frequencies than for the lower frequencies. Thus, when the transducer is removed and replaced between successive threshold estimates, it is expected, from physical principles alone, that the intrasubject reliability of the estimates should be better at the lower frequencies. Previous studies, however, have shown that the intrasubject reliability of threshold estimates is nearly the same at both the low (0-8 kHz) and the high (8-16 kHz) frequency regions. A possible explanation for these anomalous results is proposed. While it is found that transducer placement increases the variability of threshold estimates more at the higher frequencies, it has also been found that conventional headphones reduce the size of the standing wave ratios compared with a hard wall termination. An additional factor is the steeper slope of the psychometric function at the higher frequencies. The combination of these factors produces a standard deviation for threshold estimates that is only about 1 dB larger at the high than at the low frequency region.

Adult↗
PubMed1995

Second malignant neoplasms following treatment for Wilm's tumor: a report from the National Wilms' Tumor Study Group.

PURPOSE: The study was undertaken to determine the incidence of second malignant neoplasms (SMNs) in patients treated for Wilms' tumor and demonstrate how the incidence varied with the initial treatment protocol. PATIENTS AND METHODS: Between October 1969 and December 1991, 5,278 assessable patients were enrolled onto the National Wilms' Tumor Study (NWTS) and by the end of 1993 had contributed 39,461 person-years to a follow-up study. Expected numbers of second cancers were calculated by applying national incidence rates to person-years classified by age, sex, and calendar year. RESULTS: Forty-three SMNs were observed, whereas only 5.1 were expected (standardized incidence ratio [SIR], 8.4; 95% confidence interval [CI], 6.1 to 11.4). Fifteen years after the Wilms' tumor diagnosis, the cumulative incidence of a SMN was 1.6% and increasing steadily. Abdominal irradiation received as part of the initial therapy increased the risk of a SMN (SIR, 1.43/10 Gy; 95% CI, 1.13 to 1.81). Doxorubicin potentiated the radiation effect. Among 234 patients who received doxorubicin and greater than 35 Gy of abdominal radiation, eight SMNs were observed, whereas only 0.22 were expected (SIR, 36; 95% CI, 16 to 72). Treatment for relapse further increased the SMN risk by a factor of 4 to 5. CONCLUSION: These results demonstrate the importance of current efforts to limit the use of intensive chemotherapy and radiation therapy, which are now applied only to patients with the most aggressive disease. Continuing close surveillance of the great majority of Wilms' tumor patients who become long-term survivors is essential for early diagnosis of SMNs and other late sequelae of therapy.

Adolescent↗
PubMed1995

Relationship between dose schedule and charges for treatment on National Wilms' Tumor Study-4. A report from the National Wilms' Tumor Study Group.

National Wilms' Tumor Study-4 was designed to evaluate the efficacy, toxicity, and cost of administration of different regimens for the treatment of Wilms' tumor. The charges for treatment with dactinomycin and doxorubicin administered by two different schedules were calculated using current charges in Buffalo, N.Y. An annual savings of approximately $779,259 could be achieved by the use of the short, pulse-intensive (i.e., single-dose) treatment regimens for all children with Wilms' tumor of stages I-IV/favorable histology. The pulse-intensive administration schedule for the treatment of children with Wilms' tumor permits administration of chemotherapy at a substantially lower total treatment cost.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

The treatment of Wilms tumor. Results of the National Wilms Tumor Studies.

The study of Wilms tumor has provided a model for the evaluation of the histopathology, prognostic factors, and multimodality therapy regimens in children and adults with rare malignant tumors. The NWTS Group has provided the scientific and administrative framework for the assessment of various treatment schemes in children with renal tumors, a research goal that could not have been realized using the resources available to either a single or a small group of institutions. These studies have yielded higher survival rates while demonstrating that therapy can be individualized according to well-defined risk factors most accurately identified in non-pretreated tumors. Thus, it has been found that treatments associated with significant acute and/or long-term morbidity are not necessary for patients with stage I or II, favorable histology Wilms tumor. Future studies may allow more accurate identification of those patients with stage III and IV/favorable histology Wilms tumor for whom treatment with an anthracycline is not necessary. If successful, this would decrease the size of the group of survivors at risk for cardiac dysfunction, which can follow the administration of even modest cumulative dosages of these agents.

Child↗
PubMed1995

Late effects of treatment for Wilms tumor.

Successfully treated patients may be at risk for a variety of organ-specific complications, depending upon the treatment administered. Former patients should be carefully screened for such complications to facilitate early intervention. Additional research is necessary to define more accurately the frequency of these complications, to identify techniques for screening of childhood cancer survivors, and to develop therapeutic regimens of equal efficacy but lower potential for long-term morbidity.

Antineoplastic Agents↗
PubMed1995

Future directions in clinical research in Wilms tumor.

The national and international cooperative study groups have provided the scientific and administrative framework for the evaluation of various treatment regimens in patients with Wilms tumor. These have yielded excellent overall survival rates while identifying prognostic factors that have permitted modulation of therapy according to well-documented risk indices. Thus, they have demonstrated that treatments associated with important acute or long-term morbidities or both are not necessary for such patients as those with NWTS stage I or II, favorable histology Wilms tumor. It is now time to move beyond the traditional randomized prospective clinical trial method, which is not suitable to the attainment of remaining goals. Attempts to decrease the intensity of treatment even more in the future will be based on stratification of patients according to the presence or absence of one or more sensitive biologic prognostic factors. Such "markers," it is to be hoped, will make it possible to eliminate cardiotoxic and nephrotoxic drugs from the treatment of all but those at high risk of relapse.

Cell Nucleus↗
PubMed1994

The relationship between microsubstaging variables, age at diagnosis, and tumor weight of children with stage I/favorable histology Wilms' tumor. A report from the National Wilms' Tumor study.

BACKGROUND: The purpose of this study was to determine the relationship between histologic microsubstaging variables, patient age, and tumor specimen weight in patients with Stage I/favorable histology Wilms' tumors. METHODS: The authors reviewed all randomized patients from the Fourth National Wilms' Tumor Study, who had Stage I/favorable histology Wilms' tumors evaluated for one or more of the microsubstaging variables: (1) the presence of an inflammatory pseudocapsule, (2) renal sinus invasion, (3) tumor in the intrarenal vessels, and (4) tumor capsule invasion. The authors determined the correlation between microsubstaging variables and age at diagnosis or tumor specimen weight. RESULTS: Patients who were younger than 2 years of age at diagnosis were significantly more likely to have all negative microsubstaging variables. Patients who had tumors weighing less than 550 g were more likely to have all negative microsubstaging variables. However, neither renal sinus invasion nor tumor in the intrarenal vessels was more frequent in tumors weighing more than 550 g. CONCLUSIONS: An age at diagnosis of younger than 2 years and a tumor specimen weight of less than 550 g are highly correlated with the absence of adverse microsubstaging variables. The clinical variables of age at diagnosis and tumor specimen weight, compared with the assessment of microsubstaging variables, have the practical advantage of being more objectively determined and not requiring a central pathologic review for confirmation.

Adolescent↗
PubMed1994

A panoramic code for sound location by cortical neurons.

By conventional spike count measures, auditory neurons in the cat's anterior ectosylvian sulcus cortical area are broadly tuned for the location of a sound source. Nevertheless, an artificial neural network was trained to classify the temporal spike patterns of single neurons according to sound location. The spike patterns of 73 percent of single neurons coded sound location with more than twice the chance level of accuracy, and spike patterns consistently carried more information than spike counts alone. In contrast to neurons that are sharply tuned for location, these neurons appear to encode sound locations throughout 360 degrees of azimuth.

Acoustic Stimulation↗
PubMed1994

Second malignant tumors following treatment during childhood and adolescence for cancer.

Many pediatric and adolescent cancer patients are treated with carcinogenic chemotherapeutic agents and radiation therapy to achieve permanent control of their malignancy. These modalities may induce a new cancer in the successfully treated patient. To identify disease and treatment factors which increased the risk of occurrence of a second malignant tumor following modern treatment for cancer during childhood or adolescence, we reviewed the courses of 1,406 previously untreated patients who were less than 20 years of age at diagnosis and were treated at Roswell Park Cancer Institute between January 1, 1960 and December 31, 1989. Eighteen patients developed a second malignant tumor, including two meningiomas, 2.65-25.65 years after diagnosis of the first cancer. The actuarial risk of a second malignant tumor was 5.6% at 25 years after diagnosis. Using Cox proportional hazards modelling, we identified prior therapy with BCNU (P = 0.0055) and doxorubicin (P = 0.0254) as the only factors that were significantly associated with the risk of a second malignant tumor. Three second malignant tumors of the central nervous system occurred following treatment with a nitrosourea. Successfully treated patients must be carefully followed to identify treatment related malignant tumors at an early stage.

Adolescent↗
PubMed1994

Factors that influence the further survival of patients who survive for five years after the diagnosis of cancer in childhood or adolescence.

To evaluate the further survival, and to identify disease and treatment factors which influence the further survival, of five-year survivors of cancer diagnosed during childhood or adolescence, we reviewed the courses of 591 previously untreated patients who were less than 20 years of age at diagnosis and survived for five years after diagnosis. Fifty-three of 143 patients who experienced disease recurrence during the first five years after diagnosis died during the period of observation, compared to 18 of 448 patients who did not experience disease recurrence during the first five years after diagnosis. The sex-specific standardized mortality ratios for the group of patients who never relapsed or relapsed more than five years after diagnosis were not significantly different from those of the New York State population. Cox proportional hazards modelling of the subgroup of patients who relapsed during the first five years after diagnosis demonstrated that disease which was treated surgically, a diagnosis of Hodgkin's disease or acute lymphoblastic leukemia, and older age at diagnosis were significantly associated with further survival in this group, whereas similar modelling of the patients who did not experience disease recurrence during the first five years after diagnosis failed to identify any variables which were associated with continued survival. The results of this study suggest that childhood and adolescent cancer patients who survive for five years without disease recurrence have a survival rate similar to that of the general population. Continued follow-up of this cohort is required to determine if the present findings can still be demonstrated as the majority of the cohort ages beyond 35 years of age.

Actuarial Analysis↗
PubMed1994

The effect of chemotherapy dose intensity on the hematological toxicity of the treatment for Wilms' tumor. A report from the National Wilms' Tumor Study.

PURPOSE: To determine the relationship between hematological toxicity and actual dose intensity of treatment of patients randomized to therapy during the first 28 months of the National Wilms' Tumor Study-4. METHODS: The mean minimum white blood cell count (WBC), platelet count (PLT), hemoglobin, and absolute neutrophil count (ANC) during the first two courses of chemotherapy and the mean number of days of hospitalization for toxicity were compared between standard and "pulse-intensive" regimens for all randomized patients entered on National Wilms' Tumor Study-4 between August 6, 1986 and December 31, 1988. The mean dose intensity of dactinomycin, vincristine, and doxorubicin received during the first two courses and the entire course of treatment was compared between standard and "pulse-intensive" regimens. RESULTS: The mean minimum WBC, PLT, and ANC were all significantly lower during the first two courses of chemotherapy for stage I patients treated with the standard regimen, compared with the "pulse-intensive" regimen. The mean dose intensity of dactinomycin and doxorubicin was significantly higher for patients treated with the "pulse-intensive" regimens, compared with the appropriate standard regimen. CONCLUSIONS: The "pulse-intensive" administration schedule for the treatment of children with Wilms' tumor permits administration of chemotherapy at a higher dose intensity without an increase in hematological toxicity.

Adolescent↗
PubMed1994

Detection of a mistuned component in a harmonic complex.

The ability to detect a mistuned component in a harmonic complex was measured as a function of harmonic number under three different stimulus procedures: simultaneous monotic, successive monotic, and simultaneous dichotic. In the first experiment, the fundamental frequency was 200 Hz, and the stimulus duration was 410 ms. The threshold obtained in the simultaneous-monotic procedure was lower than those obtained in the other two procedures, especially for harmonics above the third. It is argued that an envelope cue associated with lower-frequency components in the power spectrum of the envelope was the primary cue for the detection of a mistuned component in a harmonic complex in the simultaneous-monotic procedure. Thresholds did not differ for successive-monotic and simultaneous-dichotic procedures, suggesting that the detection of the mistuning was mediated above the level of the cochlea. In the second and third experiments, the stimulus duration and the fundamental frequency of the complex was altered. The envelope cue seemed to be weakened by decreasing the stimulus duration and by increasing the fundamental frequency.

Adolescent↗
PubMed1994

Further studies of a maximum-likelihood yes-no procedure.

Absolute thresholds were estimated for pure tones of 500, 1000, and 2000 Hz using both a maximum-likelihood yes-no procedure and a traditional three-down one-up forced-choice adaptive procedure. Threshold estimates obtained with the two procedures were highly correlated. In the maximum-likelihood yes-no procedure, the false-alarm probability was poorly estimated. A simple change in that procedure produced less-biased estimates of the false-alarm rate. In a second experiment, the influence of the false-alarm rate on the threshold estimates was investigated. The listeners' absolute thresholds were estimated when they adopted either a liberal or conservative criterion for detecting the signals. Data were collected using both a constant-stimulus yes-no procedure and a maximum-likelihood yes-no procedure. Threshold estimates are 5 to 6 dB higher for the low than for the high false-alarm rates. Psychometric functions based on a stimulus-power model provided the best fit to the data obtained with the constant-stimulus method. This stimulus-power model was used to produce the assumed psychometric function in the maximum-likelihood yes-no procedure. Computer simulations were conducted to determine how threshold estimates were affected by the listener's inattention or by mismatches between the slope parameter of the listener's psychometric function and that assumed in the maximum-likelihood procedure.

Attention↗
PubMed1994

Treatment of children with stages II to IV anaplastic Wilms' tumor: a report from the National Wilms' Tumor Study Group.

PURPOSE: To evaluate the effect of the combination of vincristine, dactinomycin, and doxorubicin with (regimen J) or without (regimen DD-RT) cyclophosphamide on the relapse-free survival of children with stages II to IV Wilms' tumor and focal or diffuse anaplasia. PATIENTS AND METHODS: We reviewed the clinical courses of all randomized patients from National Wilms' Tumor Study (NWTS)-3 and NWTS-4 with stages II to IV anaplastic Wilms' tumor, and determined the 4-year relapse-free survival rate separately for those with focal or diffuse anaplasia. Anaplasia was evaluated using newly developed topographic definitions for focal and diffuse anaplasia. RESULTS: The 4-year relapse-free survival rate for five children with focal anaplasia who received regimen DD-RT was 80.0%, compared with 100.0% for eight children who received regimen J (P = .68). The 4-year relapse-free survival rate for 29 children with diffuse anaplasia treated with regimen DD-RT was 27.2%, compared with 54.8% for 30 children treated with regimen J (P = .02). CONCLUSION: We conclude that children with focal anaplasia have an excellent prognosis when treated with vincristine, doxorubicin, and dactinomycin. The addition of cyclophosphamide to the three-drug treatment regimen improved the 4-year relapse-free survival rate of children with stage II to IV diffuse anaplasia. This result suggests that further intensification of the treatment regimen for children with diffuse anaplasia may result in an additional improvement in prognosis.

Anaplasia↗
PubMed1994

Treatment of children with clear-cell sarcoma of the kidney: a report from the National Wilms' Tumor Study Group.

PURPOSE: To evaluate the effect of the sequential addition of doxorubicin (DOX) and cyclophosphamide (CTX) to the combination of vincristine (VCR) and dactinomycin (AMD) on the relapse-free survival of children with clear-cell sarcoma of the kidney (CCSK). PATIENTS AND METHODS: We determined the 6-year relapse-free survival rate for patients with CCSK treated on National Wilms' Tumor Study (NWTS)-1, NWTS-2, or NWTS-3 with the combination of VCR and AMD, with or without DOX, and for patients treated on NWTS-3 with the combination of VCR, AMD, and DOX with (regimen J) or without (regimen DD-RT) CTX. RESULTS: The 6-year relapse-free survival rate for the eight children with CCSK treated with VCR, AMD, and radiation therapy was 25.0%, compared with 63.5% for the 58 children treated with VCR, AMD, DOX, and radiation therapy (P = .09). The 6-year relapse-free survival rate for children with CCSK treated on regimen DD-RT was 64.6%, compared with 58.2% for those treated on regimen J (P = .79). CONCLUSION: We conclude that the addition of DOX to the combination of VCR plus AMD appeared to improve the 6-year relapse-free survival rate of children with CCSK. The addition of CTX in the dose and schedule used in NWTS-3 did not improve the 6-year relapse-free survival rate of children with CCSK. Because 30% of relapses occurred more than 2 years after diagnosis, prolonged follow-up evaluation of patients with CCSK is necessary.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Preoperative therapy for intracaval and atrial extension of Wilms tumor.

BACKGROUND: Primary surgical management of Wilms tumor with intravascular tumor extension is associated with significant morbidity. Retrospective analysis of a group of Wilms tumor patients with intravascular tumor extension treated with preoperative therapy was performed to evaluate the feasibility of this approach. METHODS: Thirty children with caval (15 patients) or atrial (15 patients) extension of Wilms tumor who received preoperative therapy were reviewed. Patients were classified according to the stage of the disease as follows: (1) Stage III, 7 patients; (2) Stage IV, 18 patients; and (3) Stage V, 5 patients. The histologic type was favorable in 20 patients, anaplastic Wilms tumor in 7, and unknown in 3. All of the children received preoperative chemotherapy, ranging from 1-16 weeks with an average of 7.2 weeks. RESULTS: One child died of progressive disease and another from toxicity before surgery. In 23 patients, a decrease in the size of the intravascular extension was noted preoperatively, without tumor embolization in any case. There was complete resolution of tumor thrombus in seven patients. Two-year survival for the entire group is 70%, with a median follow-up period of 21 months. CONCLUSIONS: The use of preoperative therapy is appropriate in selected patients with extensive intravascular tumor involvement. Surgical management was facilitated in the majority of cases due to shrinkage of the primary tumor and reduction in the size of the tumor thrombus.

Antineoplastic Combined Chemotherapy Protocols↗