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Biomedical subjects

M L Hicks

Publications and source records attributed to M L Hicks.

At least 19 recordsLinked to original sources
PubMed1999

Psychophysical measures of auditory nonlinearities as a function of frequency in individuals with normal hearing.

In order to gain a better understanding of how auditory nonlinear phenomena vary as a function of location along the cochlea, several psychophysical measures of nonlinearity were examined as a function of signal frequency. Six normal-hearing individuals completed three experiments, each designed to measure one aspect of nonlinear behavior: (1) the effects of level on frequency selectivity in simultaneous masking, measured using notched-noise maskers at spectrum levels of 30 and 50 dB, (2) two-tone suppression, measured using forward maskers at the signal frequency (fs) and suppressor tones above fs, and (3) growth of masking, measured using forward maskers below fs at a signal/masker frequency ratio of 1.44. Four signal frequencies (375, 750, 1500, and 3000 Hz) were tested to sample the nonlinear behavior at different locations along the basilar membrane, in order to test the hypothesis that the apical (low-frequency) region of the cochlea behaves more linearly than the basal (high-frequency) region. In general, all three measures revealed a progressive increase in nonlinear behavior as signal frequency increased, with little or no nonlinearity at the lowest frequency, consistent with the hypothesis.

Adult↗
PubMed1998

The National Cancer Data Base report on endometrial carcinoma in African-American women.

BACKGROUND: Although the incidence of uterine carcinoma is lower among African-American women compared with white women, the mortality rates are higher for African-American patients. This report is part of an ongoing series on gynecologic malignancies in African-American women. METHODS: Hospital registry reports collected by the National Cancer Data Base were used to describe some of the differences in case presentation and management characteristics of endometrial carcinoma in these two groups. The cases represented 52,307 Non-Hispanic white and 3226 African-American women diagnosed with primary carcinoma of the endometrium between 1988-1994. RESULTS: More African-American patients were diagnosed with less favorable histologies than white patients, at more advanced stages of disease, and with less tumor differentiation. Income had no effect on stage or grade. African-American patients were treated less often for their tumor at every stage of diagnosis compared with white women. Income generally had no effect on whether treatment was provided, but limited income was associated with a lack of treatment in African-American patients with American Joint Committee on Cancer Stage IV tumors. African-American women were less frequently treated surgically and, among surgically treated patients at advanced stages of disease, they received adjuvant radiotherapy less often and chemotherapy more often than white patients. Five-year survival was poorer for African-American women, even for patients with the more favorable Stage I adenocarcinoma who were treated surgically. CONCLUSIONS: All patients, regardless of race, should be treated appropriately as dictated by medical and prognostic factors and not by race. Although no screening methods currently exist for endometrial carcinoma, the development of procedures for identifying patients at risk for the prognostic factors that lead to a poor outcome should be a primary focus.

Adult↗
PubMed1998

Sphere spectrophotometer versus human evaluation of tooth shade.

The purpose of this study was to compare an objective to a subjective method of tooth shade evaluation using the SP78 sphere spectrophotometer and human visual analysis. Twenty extracted fully developed human maxillary teeth had their L* values (lightness) read by the SP78 on day 1 and then again on day 14. Using a blind method, five human evaluators then attempted to match shade tabs from a six-tab experimental Vita shade guide to the same teeth on days 1 and 14. The SP78 L* values read for each tooth were evaluated for a match between those obtained on day 1 and those read on day 14. The results of human evaluation of tooth shade were compared among the evaluators and then between themselves over time. Finally, the ability of human evaluators to match tooth shade was compared with the results obtained with the SP78. The SP78 reproduced L* readings within the standard error of the machine (< or = 1.0) in 16 of 20 (80%) teeth. In contrast, interevaluator agreement expressed as majority agreement (3, 4, or 5 of 5 evaluators agreeing) was only 10 of 20 (50%) teeth on day 1 and 13 of 20 (65%) teeth on day 14. Intraevaluator agreement over the experimental period ranged from 20 to 60%. The results of this study confirm that human evaluation of tooth shade is unreliable and that the SP78 sphere spectrophotometer can provide a more predictable and accurate method of evaluating tooth shade in vitro. This finding opens up a new avenue of investigation for testing the effectiveness of materials and techniques in bleaching discolored teeth.

Color↗
PubMed1998

Effect of smear layer removal on bleaching of human teeth in vitro.

The purpose of this study was to evaluate objectively in vitro the effectiveness of bleaching artificially discolored teeth with or without the smear layer present using sodium perborate mixed with sterile water or 35% hydrogen peroxide (H2O2). Seventy fully developed maxillary anterior teeth were artificially stained with human hemoglobin and separated into one control and four experimental groups. After the smear layer was removed on half the experimental teeth and left intact on the other half, all of the teeth were bleached intracoronally with sodium perborate and 35% H2O2 or sodium perborate plus water. The bleaching agents were applied twice over a 6-day period. The changes in tooth shade were objectively analyzed using a SP78 sphere spectrophotometer at 1, 30, and 60 days postbleaching. The presence or absence of the smear layer did not significantly influence the outcome of bleaching (p > 0.05). The teeth bleached with sodium perborate and 35% H2O2 were significantly lighter than the teeth bleached with sodium perborate and sterile water (p < 0.0001) at each experimental period. Based on the findings of this study, it is not advantageous to remove the smear layer before intracoronal bleaching.

Borates↗
PubMed1998

Apical extrusion of debris using two hand and two rotary instrumentation techniques.

The purpose of this study was to investigate the quantity of apical debris produced in vitro using two hand and two rotary instrumentation techniques. Sixty minimally curved, mature human mandibular premolars with single canals were divided into 4 groups of 15 teeth each and prepared using step-back instrumentation with K-files, balanced force with Flex-R files, Lightspeed nickel-titanium instruments, or .04 taper ProFile Series 29 rotary nickel-titanium files. Debris extruded through the apical foramen during instrumentation was collected on preweighed filters. The mean weight of extruded debris for each group was statistically analyzed using a Kruskal Wallis one-way analysis of variance and a Mann-Whitney U rank sum tested. Although all instrumentation techniques produced apically extruded debris, step-back instrumentation produced significantly more debris than the other methods (p < 0.0001). There was no difference between balanced force hand instrumentation and the two rotary nickel-titanium instrumentation methods (p > 0.05). Hand or engine-driven instrumentation that uses rotation seems to reduce significantly the amount of debris extruded apically when compared with a push-pull (filing) technique. Decreased apical extrusion of debris has strong implications for a decreased incidence of postoperative inflammation and pain.

Bicuspid↗
PubMed1998

The odontogenic keratocyst: a potential endodontic misdiagnosis.

Odontogenic keratocysts manifest themselves as radiolucencies that can appear anywhere in the maxilla or mandible, including periradicular areas; they may thus masquerade as lesions of endodontic origin. This retrospective study examined 239 odontogenic keratocysts received by the Oral Pathology Laboratory at Temple University School of Medicine over a 3-year period. Twenty-one (9%) of the cysts received were located periradicularly; of these 21, 12 (57%) were associated with nonvital or endodontically treated teeth and thus mimicked lesions of endodontic origin. Because of its aggressive nature and tendency to recur, the periradicular odontogenic keratocyst should be included in the differential diagnosis of lesions that are refractory to endodontic treatment.

Adult↗
PubMed1997

The National Cancer Data Base report on malignant epithelial ovarian carcinoma in African-American women.

BACKGROUND: Epithelial ovarian carcinoma is the fifth most common cause of cancer death among African-American women. Although the incidence rate of ovarian carcinoma for whites is higher than that for African Americans, the relative survival rate for African Americans is poorer. METHODS: Data were cases submitted to the National Cancer Data Base for invasive epithelial tumors of the ovary diagnosed between 1985-1988 and 1990-1993. African-American women with epithelial ovarian carcinoma were compared with non-Hispanic white women with the same disease. The groups of white women with which African-American women were compared were classified as "White-same facility" and "White-other facility." "White-same facility" were white patients from hospitals that contributed a substantial proportion of African-American patients. "White-other facility" were white patients from hospitals that contributed few or no African-American patients. No patient had a history of prior cancer. RESULTS: African-American women with advanced invasive epithelial ovarian carcinoma were less often treated with combined surgery and chemotherapy and more often treated with chemotherapy only. African-American women were twice as likely as white women not to receive appropriate treatment. African-American women had poorer survival rates than white women from the same or different hospitals, regardless of income. Among staged cases, African-American women were more often diagnosed with Stage IV disease than either group of white women. CONCLUSIONS: The current study findings show that African-American women with advanced epithelial ovarian carcinoma received less aggressive treatment than white women and had a poorer prognosis.

Adult↗
PubMed1997

Effect of heat sterilization on the torsional properties of rotary nickel-titanium endodontic files.

The purpose of this study was to determine whether heat sterilization adversely effects the torsional properties of rotary nickel-titanium files, making them more prone to fracture under torsional stress. Nine hundred sizes 2 through 10 Profile Series 29.04 taper files were divided into groups of 10 files each and sterilized 0, 1, 5, or 10 times in the steam autoclave, Statim autoclave, or dry heat sterilizer. Then, they were subjected to torsional testing in a Torquemeter Memocouple. Complete data were collected for sizes 2 through 7, but not for sizes 8 through 10 because their torque resistance exceeded the testing limits of the Torquemeter Memocouple. A one-way analysis of variance was used to compare all experimental groups in sizes 2 through 7 with their unsterilized controls (p < 0.05). Fifty-four comparisons were made for torsional strength and 54 for rotational flexibility. Ten significant changes occurred for torsional strength and 10 for rotational flexibility. Eight of 10 changes in torsional strength were increases. Fifty-two of 54 (96.3%) comparisons for torsional strength and 47 of 54 (87%) for rotational flexibility showed a significant increase or no change. Therefore, heat sterilization of rotary nickel-titanium files up to 10 times does not increase the likelihood of instrument fracture.

Analysis of Variance↗
PubMed1997

Racial differences in surgically staged patients with endometrial cancer.

This study examined whether differences in survival for endometrial cancer attributed to race are primarily associated with socioeconomic status, comorbid illnesses, molecular genetic alterations, and other disease-related characteristics identified as poor prognostic factors. One hundred fifty-two surgically staged patients with endometrial cancer (37 African-American and 115 European-American women) treated from 1990 to 1994 were analyzed for differences in demographics, disease-related characteristics, and survival. Survival was poorer for African-American women than for European-American women. African-American women had lower socioeconomic status and a higher prevalence of poor prognostic factors. Surgical stage, positive peritoneal cytology, angiolymphatic invasion, cervical stromal involvement, and a history of other malignancies were similar between the two groups. The most important predictors of survival were age at diagnosis, surgical stage, myometrial invasion, positive peritoneal cytology, cervical stromal involvement, tumor grade, aneuploidy, histology, S-phase fraction, number of poor prognostic factors, and race. Racial differences in survival were not explained by socioeconomic status, comorbid illnesses, or estrogen use. When incorporating the number of poor prognostic factors in a survival model with race and surgical stage, race ceased to be of significant prognostic value. In an analysis restricted to women with poor prognostic factors, this phenomena also occurred after adjusting for the number of poor prognostic factors. These findings suggest that the cumulative number of poor prognostic factors, not race, is a more important predictor of survival in endometrial cancer.

Aged↗
PubMed1995

Gynecologic cancer among the socioeconomically disadvantaged.

It is difficult to discern the true dimensions of the relationship between poverty and gynecologic cancer. In well designed studies of patients with gynecologic cancers, demographic stratification usually is performed based on race/ethnicity, age, or geographic locale, but not on economic class. The unstated assumption of many of these reports is that women of color, inhabitants of rural communities, and older women are all poor. Although it is true that these populations are overrepresented among the poor, unless the variable of economic class is specifically evaluated, the broad nature of the problem may go unappreciated: the status of gynecologic cancers among the poor is primarily a reflection of a deeply rooted structural problem in the U.S. economy, the reverberations of which are experienced by all women who cannot afford regular health care. When women are poor and have gynecologic cancers, they often seek orthodox health care only after the symptoms have become unbearable. Explanations of this phenomenon include underlying feelings of pessimism, fatalism, or low self-esteem; faith in a belief system that does not regard the physician as the person to whom one goes for prevention or treatment of diseases; inaccessibility of health care facilities; experiences interpreted as degrading once health care facilities are accessed; high risk behavior and inability to pay. Programs that find effective ways around structural and functional problems of daily life and that respect and understand cultural norms have the best chance of finding temporary solutions to this national problem.

Female↗
PubMed1995

Some factors influencing comodulation masking release and across-channel masking.

The purpose of this study was to determine whether comodulation masking release (CMR) and across-channel masking (ACM) are by-products of a similar across-channel mechanism. This was addressed by examining how the two are affected by stimulus manipulations expected to influence their magnitude. Subjects were required to detect a 1000-Hz signal in the presence of a masker that consisted of a 1000-Hz (on-frequency) component alone or that component and up to six flanking components (500, 600, 700, 1300, 1400, and 1500 Hz). The on-frequency and flanking components typically were sinusoidally amplitude modulated at 10 Hz, although not necessarily in phase with one another. In experiment 1, the amount of CMR and ACM was highly influenced by whether the signal consisted of one or three 50-ms tone bursts; in fact, ACM was only observed when the signal was a train of three 50-ms tone bursts. In experiments 2 and 3, CMR tended to increase as the modulation depth or the number of flanking components increased, whereas ACM was relatively unaffected by these manipulations. In addition, ACM was observed under dichotic situations, whereas CMR was not. Taken together, the results suggest that ACM and CMR may be mediated by different mechanisms.

Adult↗
PubMed1995

Squamous cell carcinoma of the cervix metastatic to an ovarian Brenner tumor.

Metastatic tumors account for approximately 10 to 15% of surgically excised ovarian malignancies (Semin Diagn Pathol 8:250-276, 1991). Although the majority of tumors arise within the female genital tract, cervical cancer is a rare source of metastasis to the ovary. Cervical carcinomas with ovarian involvement are usually advanced lesions with lymph node involvement (Am J Obstet Gynecol 166:50-53, 1992; Cancer 71:407-418, 1993). We present a case of Stage IIB squamous cell carcinoma of cervix metastatic to an ovarian Brenner tumor. Our purpose in presenting this case is to report useful histologic features in the diagnosis of this rare combination of tumors. We are not aware of any other published reports of this entity.

Brenner Tumor↗
PubMed1995

Can you screen for ovarian cancer?

Screening for ovarian cancer has become an area of great interest because of the high mortality rate associated with advanced ovarian cancer. This article discusses the requirements for a test to be considered a screening modality, outlines the current methodology used in ovarian cancer screening, addresses the shortcomings as well as problems related to cost effectiveness with the current screening modalities, and identifies special circumstances in which ovarian cancer screening may be beneficial.

CA-125 Antigen↗
PubMed1994

Colonic anastomosis using the valtrac biofragmentable anastomosis ring: a new and useful surgical technique in gynecologic oncology.

Patients with a primary malignancy of the female genital tract may present with the majority of their disease confined to the pelvis. Not infrequently, infiltrating contiguous extension of disease may involve the rectosigmoid colon, resulting in symptoms of partial obstruction. This presentation in the patient with an epithelial ovarian malignancy may represent a patient that can be adequately cytoreduced if a segmental resection of the rectosigmoid colon is performed. Following resection, the continuity of the lower GI tract can be restored by anastomosis of the proximal and distal ends of the colon. In our institution three patients explored for large abdominal pelvic masses required segmental resection of the rectosigmoid colon. In each patient the colonic anastomosis was performed using the valtrac biofragmentable anastomosis ring (V-BAR). None of the patients experienced any intraoperative complications, and postoperatively there was no evidence of any anastomotic leaks. The average time of return of GI function was 6 days and there was no prolongation of their hospital stay. Currently, with 3 months of follow-up no patients have reported any symptoms suggestive of anastomotic stricture. Although our experience is limited, we found that this technique can be performed much faster than traditional hand-sewn or staple techniques. We submit that in the presence of uncompromised colon, the V-BAR is a safe and effective new alternative for colonic anastomosis in gynecologic oncological surgery.

Anastomosis, Surgical↗
PubMed1993

Survival in patients with paraaortic lymph node metastases from endometrial adenocarcinoma clinically limited to the uterus.

PURPOSE: The purpose of this study was (a) to evaluate the incidence of paraaortic lymph node metastasis from adenocarcinoma of the endometrium clinically limited to the uterus (1971 FIGO Stages I and II) and (b) to report the 5 year disease-free survival of patients with histologically documented paraaortic lymph node metastasis from endometrial adenocarcinoma clinically limited to the uterus treated on two separate protocols. METHODS AND MATERIALS: From June 1979 to June 1990, 109 patients underwent staging paraaortic lymphadenectomy or paraaortic lymph node biopsy at the time of total abdominal hysterectomy and bilateral salpingo-oophorectomy for adenocarcinoma of the endometrium clinically limited to the uterus. Patients with histologically documented paraaortic lymph node metastasis were treated on two protocols: (a) pelvic radiation (5,040 cGy) plus progestins or (b) pelvic radiation therapy (5,040 cGy) plus paraaortic radiation (4,500 cGy). RESULTS: Paraaortic lymph node metastases was primarily associated with grade 3 tumors (34.4%) and deep myometrial invasion (42%) and was present in 17.4% (19) of 109 patients. None of the women treated with pelvic radiation therapy and progestins survived five years disease-free. In contrast, the 5 year disease-free survival was 27% for patients treated by pelvic and paraaortic radiation. CONCLUSIONS: Since all patients with macroscopic metastases to the paraaortic lymph nodes developed recurrent cancer and only a small percentage of those with microscopic metastases to the paraaortic lymph nodes survived disease-free at 5 years, improved survival for patients with paraaortic lymph node metastases will necessitate the addition of effective cytotoxic chemotherapy to pelvic and paraaortic radiation.

Adenocarcinoma↗
PubMed1993

Predictive value of serum CA125 following optimal cytoreductive surgery during weekly cisplatin induction therapy for advanced ovarian cancer.

One hundred seventy-one patients with epithelial ovarian cancer were treated on a prospective protocol of weekly cisplatin induction (1 mg/kg weekly for four courses) followed by monthly cisplatin (50 mg/m2), Adriamycin (50 mg/m2), and cyclophosphamide (750 mg/m2). Seventy-five patients with FIGO stage III or IV disease who underwent optimal cytoreductive surgery (<2 cm residual disease) were treated on this protocol and had weekly as well as monthly serum CA125 levels measured. A retrospective analysis was performed in order to determine if a > or = 50% fall in elevated serum CA125 levels during weekly cisplatin induction therapy would be predictive of findings at second look operation, normalization of serum CA125 levels (< 35 u/ml) immediately prior to the third course of multiagent chemotherapy, and to determine the impact of such a decline on median progression-free interval. Positive predictive values for this parameter with respect to findings at second look operation ranged between 38% and 50% (P > 0.05). Positive predictive values for this parameter with respect to normalization of serum CA125 levels immediately prior to the third course of multiagent chemotherapy ranged between 64.2% and 89.6% (P > 0.05). Logistic regression analysis demonstrated that a > or = 50% fall observed in CA125 levels during four weekly courses of chemotherapy served as an independent predictor of normalization of serum CA125 levels (<35 u/ml) following two courses of multiagent chemotherapy (P = 0.009) and improved median progression-free interval (P = 0.04). Eighteen patients demonstrated a rise in serum CA125 levels during weekly induction cisplatin chemotherapy. Only one of these patients (5.5%) demonstrated a surgical complete response at the end of standard therapy.

Adult↗