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Biomedical subjects

D Carter

Publications and source records attributed to D Carter.

At least 199 records · Page 11Linked to original sources
PubMed1985

Dual-energy projection radiography in the evaluation of femoral neck strength, density, and mineralization.

Two different dual-energy projection radiography techniques were utilized in an attempt to predict femoral neck strength, bone density, and bone mineral content in 19 pairs of cadaver specimens. Positive simple linear correlation was observed between dual-energy scanned projection measurements and dry density, ash fraction, cross-sectional cortical bone area and, to a lesser degree, force required for fracture, but not trabecular bone volume, failure time, or Singh trabecular grade. Dual-energy film radiography was found to be a less reliable indicator of femoral neck strength, density, and mineral content. Dual-energy scanned projection results related linearly to mineral-equivalent solution (K2HPO4) concentration, and demonstrated long-term reproducibility in repeated specimen studies. Correction factors derived to account for differences in femoral size and rotation were shown to be reliable over a moderate range of neck projections. Although bone mineral measurement at other sites may provide comparable or greater information concerning hip fracture risk, dual-energy scanned projection radiography appears to be a useful technique for assessment of bone density, mineral content, and strength in the femoral neck.

Absorptiometry, Photon↗
PubMed1985

Carcinomas of the lung with neuroendocrine differentiation.

While there are examples of each of the histologic types of bronchogenic carcinoma in which ectopic hormone production has been demonstrated, three groups of lung cancers manifest this type of differentiation with great regularity. These are the carcinoid, atypical carcinoid, and the small cell carcinoma, which have been called neuroendocrine carcinomas of the lung. The carcinoids are neoplasms with a heterogeneous array of histologic appearances that share relatively uniform nuclear features, the absence of both tumor necrosis and mitotic figures, and a good prognosis. Neuroendocrine differentiation is demonstrable with such regularity in carcinoids that the diagnosis is not considered tenable in the absence of at least one of the following features: argyrophilia, the demonstration of neuron-specific-enolase or neuropeptides by immunohistochemistry or other techniques, or the demonstration of numerous dense-core membrane-bound granules, usually 150 to 250 nm in diameter, by electron microscopy. The atypical carcinoids (well or moderately differentiated neuroendocrine carcinomas) share the neuroendocrine differentiation of the carcinoids and many of their histologic features, but are distinguished by the presence of tumor necrosis, more anaplastic large cell nuclei with numerous mitotic figures, and a distinctly worse prognosis. They are a heterogeneous lot with some similarities to carcinoids, small cell carcinomas, and large cell or adenocarcinomas. The demonstration of at least one of the neuroendocrine features listed above is considered necessary for this diagnosis. Small cell carcinoma is also a heterogeneous group of neoplasma primarily distinguished by their finely granular chromatin pattern which correlates with a much worse prognosis but a higher likelihood of response to chemotherapy and radiotherapy. Many small cell carcinomas share the neuroendocrine differentiation of the carcinoids or atypical carcinoids, but some do not and the demonstration of these features is not a requisite for inclusion in the small group. The morphologic demonstration of neuroendocrine differentiation may be more difficult in small cell carcinomas, but they more frequently produce clinically important amounts of ectopic neuropeptides. While the term neuroendocrine carcinoma of the lung includes several quite different entities and does not by itself convey histogenetic or prognostic implications, the demonstration of neuroendocrine differentiation in pulmonary neoplasms is an important procedure when combined with the recognition of other cytologic and histologic features.

Aged↗
PubMed1985

Squamous cell carcinoma of the lung: an update.

Squamous cell carcinoma of the lung has been well studied and can be characterized as having a precancerous, preclinical, and clinical phase. In the precancerous phase, it is now known that the development of carcinoma may parallel that of squamous metaplasia, but is fundamentally different and only related by virtue of similar cytoplasmic differentiation. Precancer progresses through dysplastic phases to carcinoma in situ and these changes can be documented by aneuploidy in the abnormal cells. Some of all these degrees of dysplasia, including carcinoma in situ, have been shown to be reversible. In the preclinical (occult) phase, 146 cases have been reported. They range in stage from superficial carcinoma in situ to invasive and metastatic unresectable carcinoma because of their close association with the hilar structures. Even though the best opportunity to cure squamous cell carcinoma is during the preclinical phase and despite the advanced stage it may reach during this phase, squamous cell carcinoma is the most curable of the bronchogenic carcinomas during its clinical phase. It appears that local spread of this tumor (T2) is of greater significance than hilar node metastases (N1) in the absence of local spread by the primary (T1).

Carcinoma, Squamous Cell↗
PubMed1984

Hypercalcemia in small cell carcinoma of the pancreas.

Although small cell carcinoma of the lung has a high incidence of skeletal metastasis and is frequently associated with paraneoplastic syndromes, it is only rarely associated with hypercalcemia. Similarly, the more unusual small cell carcinoma of the pancreas has not been associated with hypercalcemia. The authors describe the first such patient with small cell carcinoma of the pancreas and hypercalcemia. Comprehensive metabolic measurements (fasting calcium excretion, renal phosphorus threshold, 1,25 dihydroxyvitamin D, 25 hydroxyvitamin D levels, nephrogenous cyclic AMP and immunoreactive PTH levels) suggest that although bone metastases were present, the hypercalcemia may have been caused in part by humoral mechanisms.

Aged↗
PubMed1984

Scar cancers of the lung: origin and significance.

The relation between scarring and the development of pulmonary neoplasia has been a topic of interest for some time. One current concept suggests that the scar is a predisposing factor in the development of a cancer. In contrast, the scar or desmoplasia observed in breast, stomach, pancreatic, and colonic neoplasms is presumed to be a host response to the neoplasm. In the present study type-specific collagen antibodies were used in an immunofluorescence assay. By taking advantage of the collagen heterogeneity present in the lung and the changes in relative amounts of different collagen types during the fibrotic response, the fibrotic processes in tumorous and nontumorous areas of individual specimens were assessed qualitatively. The findings are consistent with the notion that the scar or desmoplasia in and around pulmonary tumors is not "mature" and inactive but rather represents an active, ongoing process, as evidenced by the continued presence of type III collagen. In contrast, areas of fibrosed lung parenchyma at some distance from the neoplasm revealed a mature, late stage of the fibrotic process, as evidenced by a decrease in type III and increases in types I and V collagen. Thus, the findings support the notion that the scarring associated with pulmonary neoplasia appears to be a host response to the tumor.

Adenocarcinoma↗
PubMed1984

Early lung cancer detection: results of the initial (prevalence) radiologic and cytologic screening in the Johns Hopkins study.

The Johns Hopkins Lung Project was designed to determine whether the addition of cytologic screening to the radiographic screening of high-risk volunteers could enhance the early detection of asymptomatic lung cancer and whether early therapeutic intervention in detected cases could significantly reduce the mortality from this disease. Male volunteers, 45 yr of age and older, who smoked at least 1 pack of cigarettes per day were recruited from the Baltimore metropolitan area. All of the 10,387 acceptable high-risk volunteers received annual chest radiographic screening. By random assignment, one half received cytologic examination of induced sputum in addition to the roentgenogram. This report describes the results of the initial screening. Compared with usual methods of clinical diagnosis, screening by both roentgenography and cytology identified a greater proportion of the lung cancer cases at an earlier stage. Screening by sputum cytology was found to improve the detection only of squamous cell carcinoma. In the dual-screen group, sputum cytology accounted for 28% of the detected cases, and resulted in 39% additional detection of lung cancer over that achieved by roentgenography. There was no corresponding decrease in prevalence. Lung cancers detected by cytology alone were found at very early stages. Although there has been an increase in average survival, much of this increase, if not all, may have resulted from lead-time and sampling bias.

Adenocarcinoma↗
PubMed1983

Intracystic papillary carcinoma of the breast. After mastectomy, radiotherapy or excisional biopsy alone.

Intracystic papillary carcinoma of the breast (IPC) was distinguished from the more common papillary intraductal carcinoma (DCIS) and infiltrating duct carcinoma with a papillary pattern. IPC was defined as a solitary tumor with a pattern recognizable as carcinoma which is confined to a dilated duct. A series of 41 such cases was collected from three institutions. Twenty-nine patients underwent mastectomy; 11 of them had axillary dissections. None of these patients had metastatic disease in the axillary lymph nodes or recurrence in the follow-up period which averaged five years. Eleven patients did not have mastectomy or radiotherapy. Eight of these patients (followed for an average of ten years) had no recurrence. The only patients who developed invasive carcinoma were those with DCIS as well as IPC in the excisional biopsy. The data suggest that IPC is much more likely to be cured by local treatment than is IPC accompanied by DCIS.

Adult↗
PubMed1983

Angiosarcoma of the breast.

Primary angiosarcoma of the breast is an unusual neoplasm generally associated with a dismal prognosis. In order to determine if there is a relationship between the histological characteristics of angiosarcoma and the clinical behavior, we studied 15 such cases obtained from the Connecticut Tumor Registry between the years 1954 and 1980. Histologically the cases were classified in three types: well differentiated, moderately differentiated, and poorly differentiated. The results show that the histologic patterns of the tumors correlated closely with the prognosis. Four of the five patients with well-differentiated lesions have remained free of disease for as long as 24 years. Three of four patients with moderately differentiated lesions and three of the six patients with poorly differentiated tumors died of disease in intervals up to 4 years. We believe that careful histologic evaluation of these tumors may be of significance in the prognosis of the patients.

Adolescent↗
PubMed1983

Phases of progressive burnout and their work site covariants: critical issues in OD research and praxis.

The term "burnout" represents a significant perspective on how people respond to their work, but the attention paid to this phenomenon has largely been clinical and often anecdotal. In this article, the authors seek to expand the analysis of burnout in ways that permit comparative analysis, especially in large populations. This study specifically addresses three questions. First, does a paper-and-pencil instrument isolate domains of burnout that are relatively consistent between people-intensive work and the broader range of activities found in a commercial enterprise? Second, can we develop phases of progressive burnout? Third, can we test the efficacy of the burnout phases by searching for regularities in a panel of 22 variables commonly thought to tap the important facets of the work site? The author's analysis shows that we can answer these three central questions affirmatively, though occasionally with complex and potentially significant qualifications. The results of the analysis provide further evidence of the usefulness of a convenient instrument for measuring burnout and also suggest that behavioral scientists will find valuable a phase model that distinguishes regular and robust covariation by using a panel of variables thought to tap the important aspects of organizational life.

Analysis of Variance↗
PubMed1982

Benign clinical behavior of immature mediastinal teratoma in infancy and childhood: report of two cases and review of the literature.

Germ cell tumors of the mediastinum can be divided into three categories: 1) mature teratomas which have all elements at a mature level; 2) immature teratomas which are similar to the mature teratomas, but also contain immature epithelial or mesenchymal elements or blastema; and 3) embryonal tumors which contains elements which are recognized as dysgerminoma, embryonal carcinoma with or without yolk sac elements, and choriocarcinoma. Immature teratomas are the rarest type, accounting for only about 1% of mediastinal teratomas. Two cases of immature teratoma of the mediastinum occurring in infants are reported. One tumor was completely excised. The child is well without evidence of disease two years later. The other immature teratoma was unresectable. Biopsy showed it to be similar to the teratoma that was excised. No postoperative treatment was given. The tumor has not changed appreciably in size, but the child has grown normally for six years so that the tumor mass, which initially filled his chest, is now evidenced as mediastinal widening. A review of the reported cases of immature teratomas in the mediastinum shows that the prognostic value of the histologic appearance of these tumors has not been developed to the same degree as it has for teratomas in the ovary or the sacrococcygeal region. The immature teratomas that occur in infants behave as mass lesions as do the mature teratomas. Immature teratomas in the mediastinum of children in their late teens and in young adults behave as highly malignant tumors similar to the embryonal carcinomas.

Female↗
PubMed1981

Search for resistances controlling canine gastric emptying of liquid meals.

Previous work has indicated that a chemoselective resistance controls gastric emptying. By use of meals of glucose or oleate, which were shown to empty spontaneously from dogs' stomachs half as fast as saline, we sought to locate this resistance by studying flow under controlled pressures in various regions of the gastrointestinal tract. In intact dogs, gastric outflow of glucose or oleate rose one-third as fast as outflow of saline as gastric pressure was raised, and this increased resistance to outflow of nutrients was unaffected by truncal vagotomy and pyloroplasty. In fistula dogs, gastroduodenal outflow rose linearly with gastroduodenal pressure gradients; outflow was markedly inhibited in a dose-related manner by intestinal oleate but not glucose. Inhibition by oleate was abolished by pyloroplasty. Glucose or oleate flowed into the small bowel from a barostat only slightly slower than saline. However, there was a strong inhibition of intestinal inflow of all three meals by gastric distension, an effect unaltered by truncal vagotomy. The findings suggest that gastric emptying is controlled by complex interactions among pressures and resistances, both within and beyond the stomach.

Animals↗
PubMed1980

The analysis of N-nitrosodimethylamine in antihistamines and cough/cold preparations.

Three antihistamines (diphenhydramine hydrochloride, methapyrilene hydrochloride, doxylamine succinate) and three commercial cough syrups have been analysed by GLC-TEA for N-nitrosodimethylamine (NDMA). Levels of 0.22-3.6 micrograms/kg N-nitrosodimethylamine and, unexpectedly, 0.35-2.7 micrograms/kg N-nitrosodiethylamine were found in the antihistamine drug samples. Of those amounts, 0.24-0.29 micrograms/kg NDMA and 0.15-0.20 micrograms/kg NDEA was shown to be inherent in the water used for analysis. Only one cough syrup contained detectable NDMA (0.05 micrograms/kg) and the level was of the order of that normally found in deionized water. The factors influencing the formation of volatile nitrosamines from these antihistamines in the human stomach are discussed.

Antitussive Agents↗