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Biomedical subjects

R Fields

Publications and source records attributed to R Fields.

At least 19 recordsLinked to original sources
PubMed2001

Complete response to neoadjuvant chemoradiation for rectal cancer does not influence survival.

BACKGROUND: Up to 30% of patients with locally advanced rectal cancer have a complete clinical or pathologic response to neoadjuvant chemoradiation. This study analyzes complete clinical and pathologic responders among a large group of rectal cancer patients treated with neoadjuvant chemoradiation. METHODS: From 1987 to 2000, 141 consecutive patients with biopsy-proven, locally advanced rectal cancer were treated with preoperative 5-fluorouracil-based chemotherapy and radiation. Clinical restaging after treatment consisted of proctoscopic examination and often computed tomography scan. One hundred forty patients then underwent operative resection, with results tracked in a database. Standard statistical methods were used to examine the outcomes of those patients with complete clinical or pathologic responses. RESULTS: No demographic differences were detected between either clinical complete and clinical partial responders or pathologic complete and pathologic partial responders. The positive predictive value of clinical restaging was 60%, and accuracy was 82%. By use of the Kaplan-Meier life table analysis, clinical complete responders had no advantage in local recurrence, disease-free survival, or overall survival rates when compared with clinical partial responders. Pathologic complete responders also had no recurrence or survival advantage when compared with pathologic partial responders. Of the 34 pathologic T0 tumors, 4 (13%) had lymph node metastases. CONCLUSIONS: Clinical assessment of complete response to neoadjuvant chemoradiation is unreliable. Micrometastatic disease persists in a proportion of patients despite pathologic complete response. Observation or local excision for patients thought to be complete responders should be undertaken with caution.

Aged↗
PubMed2001

A view through a different lens ... strategies for increasing the number of African American nurses.

These strategies emphasize nursing as a viable career option comparable to other careers often selected by African American students. Psychosocial issues as well as academic issues related to recruitment and retention were addressed by concentrating efforts on individuals interested in nursing, and academically prepared for the rigors of a university program. These strategies offer short-term and long-term remedies to the problem of shortage of African American professional nurses. A new paradigm for increasing the number of African American nurses is needed. To be effective, it is time for colleges of nursing to view recruitment and retention of African American individuals into the profession of nursing through a different lens.

Black or African American↗
PubMed1998

Significance of radiographic cardiomegaly in orthotopic heart transplant recipients.

OBJECTIVE: The purpose of this study is to evaluate the clinical significance of radiographic cardiomegaly in orthotopic heart transplant recipients and to identify causative anatomic and physiologic parameters. MATERIALS AND METHODS: We retrospectively compared the cardiothoracic ratio (CTR) measured using standard posteroanterior chest radiography with left ventricular end-diastolic diameter and left ventricular ejection fraction measured on two-dimensional echocardiography; right ventricular systolic pressure; and systolic, diastolic, and mean blood pressure measured at biopsy in 46 heart transplant recipients. RESULTS: Twenty-eight (61%) of the 46 patients had radiographic cardiomegaly. When we compared heart transplant recipients who had a CTR greater than 0.5 with recipients who had a CTR less than or equal to 0.5, we found no significant difference between their respective left ventricular end-diastolic diameters, left ventricular ejection fractions, right ventricular systolic pressures, systolic blood pressures, or mean blood pressures. A statistically significant difference existed between the mean values of diastolic blood pressure for transplant recipients with and without radiographic cardiomegaly. We found no significant correlation between CTR and left ventricular end-diastolic diameter, left ventricular ejection fraction, systolic blood pressure, diastolic blood pressure, or mean blood pressure. CONCLUSION: The statistically significant difference between the mean values of diastolic blood pressure of transplant recipients with and without radiographic cardiomegaly is clinically insignificant and unlikely to account for the finding of radiographic cardiomegaly. We conclude that radiographic cardiomegaly, which occurs frequently in heart transplant recipients, does not correlate with anatomic or physiologic parameters obtained under the same conditions. Radiographic cardiomegaly in heart transplant recipients does not connote allograft dysfunction or heart failure.

Adult↗
PubMed1993

Abnormal regulation of ribosomal protein S6 kinase by insulin in skeletal muscle of insulin-resistant humans.

Insulin resistance in Pima Indians appears to result from a post-receptor impairment of insulin signal transduction that affects only some responses to insulin. To identify the primary lesion responsible for insulin resistance, we investigated the influence of insulin on ribosomal protein S6 kinase activities in skeletal muscle of insulin-sensitive and insulin-resistant nondiabetic Pima Indians during a 2-h hyperinsulinemic, euglycemic clamp. In sensitive subjects, S6 kinase activity was transiently activated fivefold over basal activity by 45 min of insulin infusion. Although basal activities in the two groups were similar, the response to insulin was delayed and restricted to about threefold over basal in subjects resistant to insulin. Two major S6 kinase activities in extracts of human muscle were resolved by chromatography on Mono Q. Peak 1, which accounted for basal activity owes to an enzyme antigenically related to the 90-kD S6 kinase II, a member of the rsk gene family. The major insulin-stimulated S6 kinase eluted as peak 2 and is antigenically related to a 70-kD S6 kinase. Our results show that insulin resistance impairs signaling to the 70-kD S6 kinase.

Adult↗
PubMed1991

Peptides mimicking selected disulfide loops in HIV-1 gp120, other than V3, do not elicit virus-neutralizing antibodies.

The positions of all 9 intrachain disulfide bonds within the envelope glycoprotein gp120 of the human immunodeficiency virus (HIV-1) have been established recently. Peptides expected to mimic some of the disulfide-bonded domains [(120-133)-(203-221); (133-138)-(164-203); (224-254); (391-425) and (385-392)-(425-452)] were synthesized. All peptides, except (120-133)-(203-221), elicited in immunized rabbits relatively high levels of antibodies reacting with gp120 in enzyme-linked immunosorbent assay (ELISA) and/or Western immunoblot assays. However, these antibodies failed to neutralize the infectivity of HIV-1. Combined with earlier reports concerning other gp120 loop peptides, these results confirm the uniqueness of the V3 (303-338) loop in encompassing a principal determinant(s) involved in virus neutralization.

Amino Acid Sequence↗
PubMed1988

Acute and late toxicity associated with sequential bleomycin-containing chemotherapy regimens and radiation therapy in the treatment of carcinoma of the nasopharynx.

Between 1975 and 1984, 33 patients with squamous cell carcinoma of the nasopharynx received adjuvant chemotherapy before and/or after definitive radiotherapy at UT M. D. Anderson Hospital. The favored chemotherapy regimens during this time were BCMF (bleomycin, cyclophosphamide, methotrexate, and 5-FU) and PMB (cisplatinum, methotrexate, and bleomycin). Total radiation doses to the primary site averaged 65 Gy for T1 and T2 lesions and 70 Gy for T3 and T4 lesions. Neck nodes were given boost treatments to a maximum of 70 Gy, depending on the extent of the disease. The outcome of treatment in these patients was compared to that of a stage-matched group of 71 patients treated during the same time period with radiotherapy alone. However, the groups were not matched with regard to histologic subtypes: 45% of the radiation-only group had prognostically unfavorable keratinizing squamous carcinomas (WHO 1) compared with 18% of the combined modality group. Overall disease-free survival at 5 years was 63% in the combined modality group and 44% in the radiation only group (p = 0.15). Both acute reactions and late treatment complications were much more frequent and severe in patients receiving combined modality treatment. In patients treated with chemotherapy prior to radiation therapy, 10/20 (50%) experienced severe acute toxicity (RTOG Grade 3 or 4) versus 9/71 (13%) in the radiotherapy-only group. Severe late normal tissue injury occurred in 15/33 (45%) of the combined modality group versus 5/71 (7.0%) in the control group. The majority of the late complications in the adjuvant chemotherapy group consisted of severe soft tissue and muscle fibrosis. The average total bleomycin dose in the patients with severe late soft tissue and muscle fibrosis was 336 mg. The actuarial risk of developing a severe late complication by 2 years after treatment was 68% in the combined modality group versus 8% in the radiation-therapy-only group (p = .001). The probability of remaining both disease-free and complication-free at 5 years was 40% in the radiation-only group and 22% in the combined-modality group (p = 0.08). Comparison of these results with other published reports emphasizes the importance of late toxicity data in assessing the ultimate value of combined modality therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Recombinant rat and murine immune interferons are phosphorylated at a single site, Ser132.

Recombinant rat (Ra) and murine (Mu) immune interferons (IFN-gamma) were found to be phosphorylated by bovine heart muscle cAMP-dependent protein kinase at a single site, in contrast to human (Hu) IFN-gamma, which was reported to be phosphorylated at two different serine residues. Chromatography of a Staphylococcal aureus V8 protease digest of Ra or MuIFN-gamma indicated that the site of phosphorylation was in the carboxy-terminal undecamer fragment of the protein. Due to inherent problems in measuring both phenylthiohydantoin-serine (PTH-serine) and PTH-phosphoserine with an automated sequenator, a novel approach, involving partial Edman degradation of aliquots of the peptide followed by high performance liquid chromatography (HPLC) analysis, was developed. It was determined that Ser132 is the exclusive site of phosphorylation for both IFNs.

Amino Acid Sequence↗
PubMed1987

Active site of human liver aldehyde dehydrogenase.

Bromoacetophenone (2-bromo-1-phenylethanone) functions as an affinity reagent for human aldehyde dehydrogenase (EC 1.2.1.3) and has been found specifically to label a unique tryptic peptide in the enzyme. Amino-terminal sequence analysis of the labeled peptide after purification by two different procedures revealed the following sequence: Val-Thr-Leu-Glu-Leu-Gly-Gly-Lys. Radioactivity was found to be associated with the glutamate residue, which was identified as Glu-268 by reference to the known amino acid sequence. This paper constitutes the first identification of an active site of aldehyde dehydrogenase.

Acetophenones↗
PubMed1986

The violated neck: cervical node biopsy prior to definitive treatment.

The intent of this study was to determine whether open neck biopsy for patients with squamous cell carcinoma metastatic to the neck influenced the biologic course of the disease or the response to treatment. One hundred ninety-two patients, treated over a 10-year period at M.D. Anderson Hospital and Tumor Institute, were reviewed; 102 of the 139 patients, whose primary site of disease was identified prior to definitive treatment, were matched with a control group of 204 patients. The results showed no significant difference in wound complications, neck recurrence, distant metastases, and 5-year survival. Also, time interval from the biopsy to subsequent treatment and the type of node biopsy did not appear to have any significant detrimental effect. On the basis of these findings, we conclude that, although it is important to refrain from proceeding with an open biopsy until a complete head and neck evaluation has been done, violation of the neck does not signify a poorer prognosis--provided adequate treatment is subsequently given.

Adolescent↗
PubMed1979

Hay fever.

Explore the source record for details and available documents.

Humans↗
PubMed1971

Micro method for determination of reactive carbonyl groups in proteins and peptides, using 2,4-dinitrophenylhydrazine.

A method is described for determining carbonyl groups that is especially suitable for use with proteins and peptides. It involves the determination of the extinction at 370nm of a sample solution after adding 2,4-dinitrophenylhydrazine. The reaction of 2,4-dinitrophenylhydrazine with pyruvoylglycine and with transaminated ribonuclease T(1) is presented; the isolation of protein hydrazones is discussed.

Aldehydes↗
PubMed1971

Purification of ribonuclease T 1 by diethylaminoethylcellulose chromatography.

A procedure is described for isolating the enzyme ribonuclease T(1) from Takadiastase, an extract of the mould Aspergillus oryzae. It involves an initial concentration of the enzyme by adsorption on DEAE-cellulose followed by gradient elution. Later the enzyme is chromatographed on the same adsorbent with an eluent of constant composition. Yields of 350-380mg of ribonuclease T(1) from 500g of Takadiastase were obtained.

Amylases↗
PubMed1971

The measurement of amino groups in proteins and peptides.

A technique is examined for determining amino groups with 2,4,6-trinitrobenzenesulphonic acid, in which the extinction at 420nm of sulphite complexes of the trinitrophenylated amino groups is measured. The sensitivity of the method is 5-200nmol of amino group. The method is especially suitable for checking the extent of blocking or unblocking of amino groups in proteins and peptides, owing to the short time required for reaction (5min at room temperature). The reaction of the reagent with thiol groups has been studied and was found to proceed 30-50 times faster than with in-amino groups of model compounds. The in(420) of a trinitrophenylated thiol group was found to be 2250m(-1).cm(-1). The reaction with several amino acids, peptides and proteins is presented. The in(420) of a typical alpha-amino group was found to be 22000m(-1).cm(-1) and that of an in-amino group, 19200m(-1).cm(-1). Difficulties inherent in the analysis of constituent amino group reactions in proteins are discussed.

Amines↗