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Biomedical subjects

K J Mitchell

Publications and source records attributed to K J Mitchell.

35 records · Page 2Linked to original sources
PubMed1995

Primary malignant small bowel tumors: an atypical abdominal emergency.

Primary malignant tumors of the small bowel are uncommon in the United States. They comprise less than 1% of all gastrointestinal malignancies, with an incidence of 2200 cases per year. The clinical presentation of small bowel tumors is frequently insidious and often overlooked by physicians. The low incidence and lack of pathognomonic symptoms are the reasons that the early diagnosis of malignant small bowel tumor is uncommon. To better understand the clinical presentation, diagnostic evaluation, management, and outcome, a review of Howard University patients with primary malignant small bowel tumors between 1970 and 1990 was conducted. Our experience concurs with the reported literature and supports the conclusion that a high index of suspicion is necessary. The diagnosis of a malignant small bowel tumor should be considered in patients with vague chronic abdominal complaints.

Aged↗
PubMed1994

Evaluation of massive volume replacement in the penetrating trauma patient.

The records of 163 penetrating trauma patients who required surgery in a 36-month period between 1988 and 1990 were reviewed. Those patients with head trauma were excluded. Thirty patients were identified as having: similar Injury Severity Scores (ISS), received at least 8 L of crystalloid, and received at least 4 units of packed red blood cells during the first 24 hours after admission. There were 22 (73%) survivors and 8 (27%) nonsurvivors. Charts were reviewed for a variety of variables to determine which characteristics distinguished nonsurvivors from survivors. The mean ISS was 30.5 +/- 5.5. As a group, nonsurvivors received more blood transfusions (14.9 +/- 4.9 versus 5.0 +/- 1.14), had longer durations of shock (55.6 +/- 18 minutes versus 19.3 +/- 11.7 minutes), and had lower core body temperatures (92.6 degrees F +/- 2.2 versus 95.1 degrees F +/- 2.4) than survivors. Nonsurvivors also had lower hemoglobin levels (7.84 +/- 1 versus 9.1 +/- 2.3) and platelet counts (134.2 +/- 14.1 versus 188.6 +/- 6.3) than survivors. In addition, nonsurvivors demonstrated greater incidence of three major risk factors than did the survivors: hypothermia (75% versus 41%), acidosis (100% versus 27%), and coagulopathy (62% versus 4.5%). Therapeutic measures to limit these risk factors for increased mortality may maximize the chance of survival in these patients.

Adolescent↗
PubMed1991

Dietary abomasal impaction in a herd of dairy replacement heifers.

An episode of dietary abomasal impaction in a herd of dairy replacement heifers was found to be caused by excess almond shells in the ration. Clinical signs and necropsy findings led to the diagnosis. Removal of the almond shells and increasing the energy and digestibility of the ration corrected the problem. Factors contributing to the dietary impactions included advanced stages of pregnancy, high energy demands of growing heifers, and cold weather. Dietary abomasal impactions are not common in dairy cattle because of the high-quality ration a dairy cow generally receives. Replacement heifers in advanced stages of pregnancy have nutritional requirements similar to those of dairy cows, yet are often nutritionally neglected. The clinical findings in this report may help make veterinarians aware of the possibility of dietary abomasal impactions in dairy replacement heifers fed low-quality feeds.

Abomasum↗
PubMed1990

Traditional predictors of performance in medical school.

This paper addresses the predictive value for performance in medical school of undergraduate grades, the Medical College Admission Test (MCAT), information on the selectivity of the undergraduate institution, and selected transcript data. The performance data examined were basic science grades; clinical science grades; scores on National Board of Medical Examiners examinations, Parts I, II, and III; and information on academic difficulty. Methodological sources of differences in validity data, including restriction in range, criterion attenuation, and method specificity, are discussed. Reported validity data affirm the substantial value of traditional academic predictors of performance in medical school. Selection committees should, nevertheless, supplement academic data with nonacademic and interview information. Their inclusion is particularly important for minority and disadvantaged applicants. Medical schools should assess the validity of their selection systems. Additional research on the relations between academic predictors and performance-based indexes of clinical competence and on the role of traditional predictors with regard to the recently declining medical school applicant pool is suggested.

Achievement↗
PubMed1990

Score reporting for the 1991 Medical College Admission Test.

In December 1988, a 16-member advisory panel, made up of medical school deans, basic science faculty, clinical scientists, medical education researchers, medical students, premedical advisers, and practicing physicians, completed a full-scale review of the format, content, and score-reporting system of the Medical College Admission Test (MCAT). The advisory panel's recommendations will shape the MCAT to be introduced in 1991. Presented here are data the panel used in deciding to keep the score scale for the upcoming MCAT. Survey data on student selection practices in U.S. and Canadian medical schools and acceptance information for 1987 applicants showed that medical schools used the scores differently within each school and between the schools in deciding whom to admit. The data demonstrated the value of the current reporting system and led the advisory panel to recommend retention of the 15-point MCAT score scale in 1991.

Canada↗
PubMed1988

An interim report on the MCAT Essay Pilot Project.

Results from four pilot administrations of the Medical College Admission Test essay question are reported. Analyses focused on (a) the performance characteristics of sample groups differentiated by gender, size of hometown, race/ethnicity, and dominant language; (b) the relationships between essay scores and academic/demographic characteristics; and (c) the reliability of one 45-minute versus two 30-minute essays. No differences were found for examinees grouped by gender and size of home community. Mean differences among the racial/ethnic groups were explained largely by reading level differences. Differences in essay performance by language group were large and unexplained by reading level differences. No relationship was found between the essay score and the academic/demographic characteristics. Reliability estimates for two 30-minute essays were higher than for one 45-minute essay; however, the 30-minute period yielded writing of poorer quality. Test-retest reliabilities for the 45-minute topics will remain the focus of future studies as will performance by examinees for whom English is a second language. The impact of the essay on the selection process will also be assessed.

Educational Measurement↗
PubMed1987

Use of MCAT data in selecting students for admission to medical school.

In the spring of 1986, medical school admissions personnel were surveyed on their institutions' admissions practices and the use of Medical College Admission Test (MCAT) data in student selection. The admissions officers listed sources of information considered in processing applications. The variables accorded high importance were: overall and science undergraduate grade-point averages, quality of degree-granting institutions, letters of evaluation, interview ratings, MCAT scores, extracurricular activities, work in areas related to health care, breadth and/or difficulty of course work, and state of legal residence. Variables judged of medium importance were: nonscience grade-point average, graduate study, narratives supplied through the American Medical College Application Service or supplemental narratives, demographic factors, and undergraduate research. The respondents divided the 15-point MCAT scale into exemplary, acceptable, and unacceptable ranges of performance. These responses varied widely among institutions. The mean response for the bottom of the acceptable range was a score of seven, and the mean for the beginning of the exemplary range was 11. In considering individual MCAT subtest scores, 34 percent of the admissions officers regarded the six scores individually and equally, 51 percent weighted the areas in ways related to their curricula, and 43 percent summed or averaged scores with equal weights at some point. Thirty-one percent used MCAT scores to adjust grade-point averages across undergraduate institutions.

Canada↗
PubMed1985

Survey of calcineurin activity towards nonprotein compounds and identification of phosphoenol pyruvate as a substrate.

Calcineurin, originally identified as a calmodulin-dependent phosphoprotein phosphatase (Stewart, A.A. et al. (1982) FEBS Lett. 137, 80-84) also uses p-nitrophenyl phosphate and phosphotyrosine as substrates (Pallen, C.J. and Wang, J.H. (1983) J. Biol. Chem. 258, 8550-8553). We have surveyed a wide range of nonprotein phosphocompounds and found that several synthetic aryl phosphocompounds serve as calcineurin substrates. Among more than 20 naturally occurring phosphocompounds tested, only phosphoenol pyruvate possesses significant calcineurin substrate activity. The phosphoenol pyruvate phosphatase activity is dependent on Ni2+ and Mn2+, is stimulated by calmodulin, and is inhibited by a monoclonal antibody to calcineurin, thus indicating that it is an intrinsic property of calcineurin. The results suggest that functional roles of calcineurin may include actions of the enzyme toward nonprotein phosphocompounds.

Amino Acids↗
PubMed1982

A prospective reappraisal of emergency endoscopy in patients with portal hypertension.

In a prospective study of emergency endoscopy in patients with portal hypertension and oesophageal varices referred to King's College Hospital with acute upper gastrointestinal bleeding, initial endoscopic examination on 90 separate consecutive hospital admissions carried out within 24 h of clinical haemorrhage showed active variceal bleeding in only 21 (23.3%) cases. Coexisting upper gastrointestinal lesions were present in 38.8% of examinations, but active bleeding from these sites was seen in only five cases (5.6%). Of the 64 cases in which no active bleeding was seen at initial endoscopy, 39 (60.9%) rebled during that admission, and repeat endoscopy in 27 of these, carried out within 1 h of this episode, revealed active variceal haemorrhage in 20 (74.1%) cases. These results indicate that variceal haemorrhage is intermittent, and, although bleeding may often stop spontaneously, a high proportion of patients subsequently rebleed, and this is invariably from varices rather than from coexisting upper gastrointestinal lesions. In addition, these findings confirm the importance of emergency endoscopy in making the correct decision about acute management.

Emergencies↗
PubMed1980

Prospective controlled trial of injection sclerotherapy in patient with cirrhosis and recent variceal haemorrhage.

64 patients with cirrhosis and recent variceal haemorrhage were studied in a prospective randomised trial of injection sclerotherapy by means of a flexible oesophageal sheath. 12 (33%) of the 36 patients in the sclerotherapy group, suffered further bleeds from varices compared with 19 (68%) of the 28 patients receiving standard medical treatment. The risk of bleeding per patient-month of follow up decreased more than threefold with sclerotherapy and the number of patients rebleeding after 2, 6, and 12 months was significantly reduced (p < 0.05). 1-year survival without further bleeding improved significantly with sclerotherapy (46% compared with 6%, p < 0.02), although the difference in overall survival assessed by cumulative life-table analysis was not statistically significant. The main complication of the technique was the development of oesophageal ulcers in some patients.

Esophageal Diseases↗
PubMed1975

Intolerance of eight ounces of milk in healthy lactose-intolerant teen-agers.

The ability of lactose-intolerant individuals to tolerate 8 ounces of milk was determined in healthy teen-agers. Thirty-two blacks were studied with 50-gm lactose tolerance tests. Nineteen (59%) had a flat blood sugar curve and 13 (39%) also developed bloating, cramps, loose stools, or diarrhea with the test. These latter 13 were defined as lactose-intolerant. Seven of the 13 lactose-intolerant teen-agers (54%) developed abdominal bloating and/or cramps after drinking 8 ounces of milk (half-pint). None had diarrhea. Eight were symptomatic with the equivalent amount of lactose (12 gm) while only one had symptoms with the monosaccharide components of lactose, glucose and galactose. The symptoms with milk and 12 gm of lactose were less severe than with the 50-gm tolerance test. A history of a prior awareness of milk intolerance was obtained from 11 of the 13 lactose-intolerant subjects. At least one half of lactose intolerant teen-agers might be expected to be symptomatic after drinking 8 ounces of milk without other food. Milk intolerance should be considered in the nutritional planning for teen-agers with special attention to members of population groups with a high prevalence of lactose intolerance.

Adolescent↗