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Biomedical subjects

J Horton

Publications and source records attributed to J Horton.

At least 163 records · Page 9Linked to original sources
PubMed1981

High-performance liquid chromatographic and field desorption mass spectrometric measurement of picomole amounts of endogenous neuropeptides in biologic tissue.

A unique combination of chromatographic separation and mass spectrometric techniques has been developed for a novel method for measurement of picomole amounts of endogenous oligopeptides in biologic tissue. High-performance liquid chromatography is utilized for rapid high-resolution separation of peptides. A new buffer system using dilute triethylamine-formic acid is utilized. The buffer system possesses excellent UV transparent properties enabling femtomole sensitivity for measurement of standard solutions of somatostatin. Use of porous polystyrenedivinylbenzene copolymer and octadecylsilyl columns facilitate retention of a peptide fraction from biologic extracts. Advantage was taken of field desorption mass spectrometric methods to eliminate chemical derivatization of peptides and to produce protonated molecular ions which retain total molecular information of the peptide. Use of appropriate internal standards and selected ion monitoring methods enabled nanogram sensitivity and, more importantly, optimized structural specificity of the compound being quantified. Results are compatible with radioimmunoassay data. Data obtained with field desorption mass spectrometry provide, for the first time, measurement of intact, chemically underivatized oligopeptides extracted form biologic matrices and significantly, provide and analytic method to calibrate radioimmunoassay data. This novel combination of methods is being applied to measurements of peptide (leu-enkephalin, met-enkephalin, somatostatin, etc.) in canine brain regions and dental pulp tissue.

Animals↗
PubMed1981

Attitudes toward cancer: I. The impact of a comprehensive oncology course on second-year medical students.

This study focuses on the change in medical students' attitudes toward cancer and related issues when the factual knowledge concerning the contemporary treatment of the cancer patient is increased. The Cancer Attitude Survey, as instrument consisting of 33 original items developed by Haley et al.9 and 27 additional items developed by the present authors, was administered to a sophomore class of medical students before and after on oncology course. Depsite the absence of formal attempts to teach specific attitudes, significant changes in attitudes were observed in responses to 18 of the 60 items (30%). After completing the course, students were more likely to favor an active role both for the patient and for the physician en each stage of the treatment process. Although students were more likely to favor aggressive treatment, they also indicated that appropriate limit should be set. Implications for teaching and for further research on attitudes and behavior are noted.

Attitude of Health Personnel↗
PubMed1981

Noninvasive evaluation of mediastinal metastases in bronchogenic carcinoma: a prospective comparison of chest radiography and gallium-67 scanning.

Evaluation of regional node involvement in patients with bronchogenic carcinoma is a crucial step in determining therapy and prognosis. Mediastinoscopy has been recommended for staging all potentially operable cases, but technical limitations and the need for anesthesia make this impractical. Gallium-67 scanning and chest radiography were prospectively compared as noninvasive means of evaluating spread to regional nodes in 75 patients with bronchogenic carcinoma in whom histologic evaluation of hilar and mediastinal nodes was performed. Gallium scanning was more accurate than chest radiography in assessing regional nodes (overall accuracy 85.3% vs. 56%, P less than 0.05). When positive, both procedures correctly indicate malignant involvement of regional nodes (85% vs. 87.3%). A negative gallium scan, however, was significantly more accurate in predicting the absence of such involvement (80% vs. 40%, P less than 0.01). Gallium scanning appears to be a reliable, noninvasive means of assessing mediastinal spread of bronchogenic carcinoma and when used in conjunction with radiographic findings, allows selection of appropriate patients for surgical staging procedures.

False Negative Reactions↗
PubMed1981

Early diagnosis of spinal epidural metastases.

Early signs of spinal cord injury on neurologic examination have been the primary indication to proceed with myelography in patients with possible spinal epidural metastases. With this approach, loss of ambulation occurs in more than one half of the patients. In an attempt to diagnose epidural metastases before the onset of myelopathy, we designed a prospective study based on the development of back pain, a precursor of spinal cord injury in nearly all cancer patients. Eighty-seven patients were studied. A high incidence of epidural metastases was found in patients with myelopathy (78 percent). In addition, patients with radiculopathy alone frequently had epidural tumor (61 percent). In 36 percent of the patients who presented with back pain but who had normal neurologic findings, there was evidence of epidural metastases on myelography; all of those patients had vertebral metastases on plain roentgenogram. Over-all, the plain roentgenogram of the spine correctly predicted the presence or absence of epidural tumor in 83 percent of the patients. Whereas 93 percent of the patients with myelopathy had more than 75 percent myelographic block, this occurred in 53 percent of those with radiculopathy and in only 33 percent of those with back pain and normal neurologic findings. In most cancer patients, spinal epidural metastases are both detectable and significantly less extensive before the onset of spinal cord injury.

Adolescent↗
PubMed1980

A direct analysis of methotrexate, dichloromethotrexate and their 7-hydroxy metabolites in plasma by high pressure liquid chromatography.

Plasma levels of methotrexate, dichloromethotrexate, and their 7-hydroxy metabolites can be determined quickly and accurately by direct analysis in a high pressure liquid chromatographic system. This system utilizes a precolumn of CO:Pell ODS resin to protect the analytical mu-Bondapak C18 column. The precolumn also provides a bed for extraction of drugs from the plasma proteins which are trapped in it. Elution with a paired ion solvent provides good recovery of methotrexate from the plasma and excellent separation on the column. The primary advantages of this system are its speed and simplicity combined with its ability to determine the plasma level of parent drug and its metabolite simultaneously.

Animals↗
PubMed1980

Prognostic effect of weight loss prior to chemotherapy in cancer patients. Eastern Cooperative Oncology Group.

The prognostic effect of weight loss prior to chemotherapy was analyzed using data from 3,047 patients enrolled in 12 chemotherapy protocols of the Eastern Cooperative Oncology Group. The frequency of weight loss ranged from 31 percent for favorable non-Hodgkin's lymphoma to 87 percent in gastric cancer. Median survival was significantly shorter in nine protocols for the patients with weight loss compared to the patients with no weight loss. Chemotherapy response rates were lower in the patients with weight loss, but only in patients with breast cancer was this difference significant. Decreasing weight was correlated with decreasing performance status except for patients with pancreatic and gastric cancer. Within performance status categories, weight loss was associated with decreased median survival. The frequency of weight loss increased with increasing number of anatomic sites involved with metastases, but within categories of anatomic involvement, weight loss was associated with decreased median survival. These observations emphasize the prognostic effect of weight loss, especially in patients with a favorable performance status or a limited anatomic involvement with tumor.

Activities of Daily Living↗
PubMed1979

Vascular access for cancer chemotherapy.

Eleven bovine heterografts were utilized in the repetitive administration of chemotherapy in 10 patients with insufficient vascular access. Six grafts remained patent until the time of death and five grafts clotted from 71 to 1110 days postoperatively. Three patients are alive and well. All grafts were initially patent and no wound infections resulted. The bovine heterograft appears to be a useful adjunct for securing vascular access for patients requiring cancer chemotherapy.

Animals↗
PubMed1979

Systolic click from a Swan-Ganz catheter: phonoechocardiographic depiction of the underlying mechanism.

Although echocardiographic manifestations of Swan-Ganz catheters have received increasing attention, auscultatory sequelae have not previously been described. In the patient described in this report, insertion of a Swan-Ganz catheter resulted in a loud mid systolic click; removal of the catheter eliminated the click. Simultaneous phonoechocardiograms suggest that the click resulted from crisp contact of the catheter against the ventricular septum. Catheter momentum was enhanced by wide excursion and systemic pressures in the right ventricle; paradoxical motion of the septum during systole may have accentuated the force of its contact with the catheter.

Cardiac Catheterization↗
PubMed1978

Estimated effect of breast self-examination and routine physician examinations on breast-cancer mortality.

We examined the effects of breast self-examination and breast examination by physicians on the stage of breast cancer at diagnosis. Clinical and pathological-staging information was compared to interview data on method of initial detection of 293 women. Tumors were detected in clinical Stage I 53.8% of the time when the detection method was routine physician examination, 37.7% when it was self-examination and only 27.0% when detection was accidental. Sixty-nine per cent of women practicing self-examination at the time of diagnosis discovered their tumor by this method. Differences were less apparent when pathological stage was considered. Tumors found during routine examination of the breast averaged 6.1 mm smaller in diameter than those discovered accidentally. We estimate that breast-cancer mortality might be reduced by 18.8% to 24.4% through self-examination or routine physician examination, respectively.

Breast↗
PubMed1978

Muscle and subcutaneous oxygen tension. Measurements by mass spectrometry after sympathectomy.

Utilizing the mass spectrometer, tissue oxygen tension (TPO2) in the resting state was measured in the extremities of ten dogs before and after lumbar sympathectomy. Although there was considerable variation between individual dogs, significant changes in tissue oxygenation were not consistently obtained in the group as a whole, althouth femoral arterial blood flow increased in all animals. Using TPO2 changes to estimate perfusion, no significant increase in nutritive flow could be demonstrated.

Animals↗