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Biomedical subjects

R R Perry

Publications and source records attributed to R R Perry.

At least 55 records · Page 3Linked to original sources
PubMed1989

Primary adrenal causes of Cushing's syndrome. Diagnosis and surgical management.

Cushing's syndrome is rare with only 20% of patients having a primary adrenal cause of hypercortisolism. We have developed a strategy to evaluate patients with suspected Cushing's syndrome and to localize the pathologic condition responsible for the hypercortisolism. This report reviews the last 11 consecutive patients who had a primary adrenal cause of hypercortisolism. Each patient had elevated 24-hour urine free cortisol and 17-hydroxycorticosteroid excretion consistent with hypercortisolism. All but one patient had undetectable plasma ACTH levels. No patient suppressed urinary steroid levels with high-dose dexamethasone and only one patient increased plasma ACTH or cortisol levels with oCRH, findings that were consistent with a pituitary-independent form of hypercortisolism. No patient had a pituitary tumor detected by computed tomography or magnetic resonance imaging, and eight patients had adrenal tumors accurately imaged. MRI of the adrenal glands correctly diagnosed adenoma in 5 of 6 patients with adenomas, carcinoma in 1 patient, and ACTH-producing pheochromocytoma in 1 patient. One tumor classified as carcinoma by MRI appeared on pathologic examination to be an adenoma. Three patients underwent petrosal sinus sampling for measurement of ACTH before and after oCRH administration, and each had petrosal sinus ACTH levels equal to peripheral levels, consistent with a primary adrenal cause of hypercortisolism. Two of these patients had typical bilateral pigmented micronodular adrenocortical disease and the third patient had macronodular adrenocortical hyperplasia. Each of the 11 patients was cured of hypercortisolism by unilateral or bilateral adrenalectomy and no patient has developed recurrent disease during the 7 to 29 month follow-up period. New modalities including the ovine CRH test, MRI, and petrosal sinus sampling have improved the evaluation of certain patients with Cushing's syndrome.

Adolescent↗
PubMed1989

Tracheoesophageal fistula in the patient with lymphoma: case report and review of the literature.

Tracheoesophageal fistula (TEF) occurs only rarely in the patient with lymphoma. Two cases are presented to illustrate the challenges in managing TEF in this patient population. Most of the 38 previously reported cases have occurred in patients who have undergone radiation therapy, although several patients have had TEF as an initial manifestation of lymphoma. TEF is usually, but not universally, associated with the presence of active lymphoma. The surgical approach should be individualized, based on the patient's overall condition, the site and size of the fistula, and sites of disease. Often a conservative surgical approach is warranted with the expectation that many of these fistulas will close after radiation therapy or chemotherapy. Patients with lymphoma-related TEF have a better prognosis than do those with TEF caused by carcinoma of the lung or esophagus.

Adult↗
PubMed1986

Role of metabolism in effects of diflubenzuron on growth of B16 melanomas in mice.

The insect growth regulator diflubenzuron (DFB), which also inhibits growth of experimental tumors in mice, was studied to determine the influence of in vivo microsomal metabolism on its antitumor activity. DFB inhibits chitin synthesis and growth of imaginal epidermis in insects and suppresses melanogenesis and uptake of nucleosides in mouse melanoma cells, but the means of cell growth regulation and the role of metabolism of DFB in such regulation have not been established. Five daily injections of DFB (total of 4000 mg/kg) into C57BL/6 mice with B16 melanomas induced an acute 11-20% decrease in tumor volume and a 2-3 day increase in the initial tumor volume doubling time (Td), but at mid-treatment tumors regained maximum (control-like) rate of volume increase. Tumors in mice conditioned with a mixed function oxidase inhibitor (CoCl2) and treated with DFB did not decrease in mean volume, but their rate of volume increase was reduced by about 75% and the Td was increased by 4.2 days. In contrast, induction of mixed function oxidase with 3-methylcholanthrene (3-MC) or beta-napthaflavone (B-NF) enhanced the effects of DFB by a factor of 1.5 to 2.0. Therefore, aromatic hydroxylation of DFB may be required for tumor growth regulation. Three metabolites of DFB--two hydroxylated forms and a scission product, 4-chlorophenylurea (CPU), were also tested for tumor growth regulation. CPU was ineffective; a form oxidized at the 3 carbon of the phenyl ring (3-OH-DFB) was only marginally effective; but the 2-carbon form (2-OH-DFB) induced a 24% decrease in mean tumor volume and a 2.4 day increase in Td. Pretreatment with 3-MC and treatment with 2-OH-DFB also resulted in a 24% decrease in tumor volume and a 2.2 day increase in Td, but also reduced tumor volume increase to 20% between the 5th and 10th days after the initial 2-OH-DFB injection, compared to a 125% increase without 3-MC. Further, 3-MC pretreatment caused the otherwise marginally effective 3-OH-DFB to become almost as effective as 2-OH-DFB. These data support our previous report that DFB alters tumor growth and show that mixed function oxidase enhances effects of DFB, 2-OH-DFB and 3-OH-DFB.

Animals↗
PubMed1986

Blood flow to transplanted fetal rat intestine.

Avascular fetal rat intestine becomes vascularized and grows and develops certain properties of normal small intestine when transplanted into the subcutaneous tissues of host syngeneic rats. We quantified the blood flow to this transplanted intestine (called "neogut") to clarify the role of angiogenesis in its growth and development. Additionally, we correlated blood flow and the growth of neogut into either patent tubular segments or large saccular segments with associated strictures. Blood flow was studied using 141Ce or 85Sr labeled microspheres. Blood flows are expressed as mean +/- SEM in (ml/min X g). Neogut blood flow (0.19 +/- 0.02) was greater than that of adjacent subcutaneous tissue (0.03 +/- 0.00, P less than 0.01) but less than that of native small bowel (0.85 +/- 0.07, P less than 0.01). The blood flow to the large saccular segments (0.10 +/- 0.01) was less than that to the tubular portions (0.27 +/- 0.02, P less than 0.01). The weight of neogut was comparable to that of native small bowel. These findings demonstrate that neogut implants stimulate angiogenesis to a degree which may be sufficient for it to absorb nutrients. Furthermore, ischemia is present in large saccular neogut segments with associated strictures. Additional investigation appears warranted to see if neogut can serve as a clinically useful small bowel substitute.

Animals↗
PubMed1986

Differential response to gamma radiation of human stomach cancer cells in vitro.

In vitro effects of radiation were studied in two permanent cell lines (AGS and SII) from two patients with adenocarcinoma of the stomach and three permanent sublines from each cell line. Radiation survival parameters for AGS and SII parent cell lines and sublines were determined after in vitro irradiation of their cells with 0.5 to 10 Gy of 60Co gamma rays. The AGS and SII cell lines had different growth properties, DNA contents and radiation survival curves. Surviving fractions of SII parent cells (76 chromosomes) after 2.0 and 10 Gy were 1.22 and 17.8 times greater, respectively, than values for AGS parent cells (47 chromosomes). Sensitivities (D0) were 1.08 and 1.45 Gy for AGS and SII parent lines, respectively. The D0 values for AGS parent cells and sublines were similar (1.01 to 1.08 Gy), but SII parent cells and sublines had D0 values of 1.45, 1.36, 1.37 and 1.12 Gy (for SII-A). Also, the SII parent cells had survival fractions after 2.0 and 10 Gy that were 1.3 and 11.3 times greater, respectively, than values for the SII-A cells. These data show differences in radiation responses among stomach cancer cell lines and sublines that may relate to DNA content, but there was no consistent correlation between radiation response and a particular cell characteristic.

Adenocarcinoma↗
PubMed1985

Mycobacterium avium infection in a silicone-injected breast.

A case of atypical mycobacterial infection (M. avium intracellulare) in a silicone-injection augmented breast is described. The silicone injection may have been a contributing factor to the development of this unusual infection. Disseminated M. avium was present in this patient, with breast involvement being suggested by the rapid appearance and disappearance of localized areas of erythema and tenderness. Aggressive treatment of these breast infections while they are still localized may prevent systemic spread. Conventional incision and drainage of the breast abscess combined with multidrug treatment directed against M. avium is the recommended therapy.

Adult↗
PubMed1984

Effects of diflubenzuron on growth of malignant melanoma and skin carcinoma tumors in mice.

The insect growth regulator diflubenzuron (DFB), which may also inhibit growth of imaginal epidermal cells in insects, was studied for antitumor activity in two mouse tumor models of epidermal origin. DFB inhibits chitin deposition, but the mechanisms by which DFB controls chitin deposition or regulates growth of insect epidermal cells are unknown. A single injection of 20 mg (800 mg/kg) of DFB into C57BL/6 mice with B16 malignant melanomas or AKR mice with skin tumors (CA 1025) induced a rapid (24 h) decrease in tumor volume in 78% and 66% of the tumors, respectively. In contrast, 85% of the melanomas and 91% of skin tumors in control mice increased in volume during the same 24-h period. Tumor volume decreased by as much as 55% for about 1% of the tumors, but the median decrease was 20% for both types of tumors. Since control tumors concommitantly increased, DFB-treated tumors decreased, relatively, to 60% of the volume of matched control tumors. After the initial volume decrease, both types of tumors resumed exponential growth resulting in an average growth curve delay, calculated for 12-14 days, of about 2.0 days. Subsequent treatment of melanomas with DFB 24 h after the initial treatment resulted in a further decrease in relative tumor volume to 40-50% of control tumor volume and a growth curve delay of 2.6 days. The most effective regimen used was 5 daily, 20-mg doses of DFB. Melanomas decreased to 40% of control tumor volume after the third injection and the mean growth curve delay was extended to 4.3 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

Effects of Cis-diamminedichloroplatinum (II) on hematopoietic stem cells in mice.

Bone marrow cell responses to therapeutic doses of cis-diamminedichloroplatinum (II) (Cis-Pt) were evaluated in female C57B1/6 mice by determining bone marrow cellularity and content of transplantable colony forming units (CFUS) after treatment. Although limitation on the dosage of Cis-Pt is generally considered to be determined by renal toxicity, methods to increase the effective use of the drug such as hydration and diuresis, alteration of time-dose schedules and combination of Cis-Pt with other drugs and radiation, warrant studies on effects of the drug on other normal tissues such as bone marrow. Cis-Pt given on a time-dose schedule that is therapeutic for mice and, in general, is equivalent to regimens recommended for clinical use, was found to be myelosuppressive. The myelosuppression was dose related in that a total dose of 16 mg/kg (2 doses at weekly interval) reduced the number of CFUS/femur to 16% of the control value, 24 mg/kg (4 doses at weekly intervals) reduced the CFUS fraction to 10-14% of the value for controls and 32 mg/kg (4 doses at weekly intervals) reduced the fraction of CFUs to 6-7% of the control value. A quantitative extrapolation of these effects to man cannot be made, however, the data indicate that myelosuppression could become a significant factor as increased doses of Cis-Pt are used clinically.

Animals↗
PubMed1981

Minority recruitment to the health professions: a matched comparison six-year follow-up.

An experiential program was designed to attract minority students to health careers and to affect the supply and distribution of health manpower in a medically underserved area. A six-year follow-up study of participants and a matched comparison group of nonparticipants indicate the value of the program. Participants were found to by employed in health careers and to achieve long-term career preferences more often than nonparticipants, even though they experienced slightly more obstacles to career attainment. Although more of the participants appeared to remain in the underserved area to practice their health profession, respondents from both groups who had achieved a health career and who had been educated in the underserved area were more likely to remain in the area to practice. This study is evidence of the value of long-term follow-up evaluation.

Career Choice↗
PubMed1980

Radiotherapy and head and neck cancer. Role of lymphocyte respontse and clinical stage.

The mean number of lymphocytes, response to phytohemagglutinin (PHA), and response to concanavalin A (Con A) in whole-blood cultures for 106 patients with head and neck cancer were 83%, 73%, and 64%, respectively, of values for healthy control individuals. During radiotherapy, lymphocyte counts declined to 44% and PHA and Con A responses declined to about one third of control values. Lymphocyte counts slowly increased after treatment to 77% of control values after two years, but responses to mitogens remained at about 40%. Responses to PHA and Con A for 38 patients who lived beyond 18 months were significantly greater before and after treatment than responses for 39 patients who died within 18 months. In general, a poor pretreatment response to PHA and Con A correlated with a poor clinical course, whereas responses near the control level indicated a good clinical course.

Carcinoma, Squamous Cell↗
PubMed1976

Lymphocyte response in patients with head and neck cancer: effect of clinical stage and radiotherapy.

Ffty-three patients with head and neck cancer tested before radiation treatment to determine numbers of blood lymphocytes and immunologic responses to mitogens of lymphocytes in whole-blood cultures had mean values that were 19% to 26% less than values for healthy individuals. Thirty patients whose disease was in stages III or IV had values similar to those in 23 patients whose disease was in stages I or II. Values for 45 patients tested at end of radiotherapy decreased to about 50% of pretreatment values; however, patients with advanced lesions experienced greater decreases (to 24% to 50%) than patients with localized lesions (to 71% to 84%). Patients with advanced lesions usually received radiation to larger areas than patients with localized lesions; therefore, the extent of decline in laboratory values was most likely dependent on volume of tissue treated.

Concanavalin A↗
PubMed1976

A follow-up evaluation of a summer health career program for minority students.

In an effort to attract minority students to health careers, a special summer education health career experience was developed. A matched comparison group design was utilized to determine the value of this program. Data were collected on both the participants and a matched comparison group three months before and six months after the program. Differences on most of the measures were not significant; however, there was a significant difference on stability of first career choice, indicating that a special summer program can and does have an effect on the participants. The study makes it clear that program effects cannot be assumed unless a follow-up evaluation is undertaken.

Career Choice↗
PubMed1976

A formative and summative evaluation model for special educational programs.

During the past two decades the problems of recruiting minority students into careers in the health fields have been addressed by many educators and various special study groups. Recent efforts by schools of medicine and allied health sciences to find viable solutions to the problem have facilitated implementation of career exploration and study-skills programs. Although the focus and sophistication of evaluation designs vary substantially among educational programs of this type, all share some common problems. The positions taken by the authors is that evaluation, both during and at the end of a program, is an essential aspect of the program and that the use of a systematic evaluation model is central to this effort. Data are presented which illustrate the utility of a systematic evaluation model when applied in a realistic test situation (an operational program for minority students). Several advantages of using this model are discussed.

Career Choice↗