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Biomedical subjects

T Walton

Publications and source records attributed to T Walton.

12 recordsLinked to original sources
PubMed1999

Comparison of ganciclovir- and immune globulin-containing regimens in preventing cytomegalovirus infection in patients with renal transplants.

The effectiveness and costs of ganciclovir compared with intravenous immune globulin (IVIG) in the prevention of cytomegalovirus (CMV) disease were studied. A retrospective analysis was conducted of renal transplant patients treated with ganciclovir during the initial hospital stay followed by three months of acyclovir therapy and a historical control group that received IVIG at one, two, four, six, and eight weeks posttransplant and acyclovir at two weeks posttransplant and continued for three months. The average drug cost for each regimen and the average direct cost of treating CMV disease in each group were calculated. The overall frequency of CMV disease was 14% in the IVIG group (n = 42) and 3% in the ganciclovir group (n = 30). CMV disease occurred less frequently in all ganciclovir-treated subgroups, but the difference was significant only in the group in which the recipient was CMV seronegative and the donor CMV seropositive. No ganciclovir-related adverse events were noted. Three IVIG-related infusion reactions were noted. Treatment with ganciclovir decreased drug costs by approximately $2,775 per patient or $83,250 for the study sample. The overall avoided cost in the ganciclovir group was $102,575 ($3,419 per patient). Ganciclovir followed by acyclovir was significantly more effective than IVIG followed by acyclovir in the prevention of CMV disease in CMV-seronegative patients who received renal transplants from CMV-seropositive donors; among all patients studied, ganciclovir did not differ from IVIG in preventing CMV infection but was considerably less expensive.

Acyclovir↗
PubMed1998

Radiation tolerance of transverse rectus abdominis myocutaneous-free flaps used in immediate breast reconstruction.

The authors determine the effects of postoperative radiation therapy on flap and local control outcomes in patients who have undergone immediate transverse rectus abdominis myocutaneous (TRAM)-free flap reconstruction after modified radical mastectomy for locally advanced breast cancer. Details of surgery, chemotherapy, and radiation therapy for 21 patients who had undergone immediate TRAM-free flap reconstruction after modified radical mastectomy were gathered retrospectively. The outcomes examined were flap complications, overall cosmesis, and local recurrence rate. Radiation therapy was indicated for large primary tumors (T3-T4), close or positive margins, or extensive nodal disease. With a mean follow-up interval of 19 months, there have been no flap complications or losses. Cosmesis was rated as excellent by 60% of patients, good by 30%, and fair by the remaining 10%. Three patients thought that radiation had improved cosmesis, one noted worse cosmesis, and the remainder thought it had no effect on cosmesis. The local control rate was 86%. Postreconstruction irradiation of TRAM-free flaps used in immediate reconstruction for locally advanced breast cancer appears safe and cosmetically acceptable.

Adult↗
PubMed1995

Release of iron from C-terminal monoferric transferrin to phosphate and pyrophosphate at pH 5.5 proceeds through two pathways.

Iron release fro C-terminal monoferric transferrin at pH 5.5 and 37 degrees C was studied as a function of chloride, phosphate, and pyrophosphate concentration. The rate constant for iron release depends linearly on chloride concentration, confirming that anion binding is mandatory for iron release, not only at pH 7.4 as has been previously reported, but also at pH 5.5. The extent of iron release is relatively small (< 20% for 1.0 M chloride). Concentrations of > 0.2 M phosphate are required for complete iron removal, but millimolar concentrations of pyrophosphate effect complete removal. The observed rate constants for iron release to phosphate and pyrophosphate change from one linear dependence to another less steep linear dependence on the concentration of these ligands, providing quantitative evidence that the two-pathway mechanism that we previously proposed for iron release at pH 7.4 persists at pH 5.5. According to this model, the pathway of iron release is determined by the nature of the anion occupying a kinetically significant anion binding site on the protein. The qualitative similarity of the current data with that recently reported for iron release from the transferrin-transferrin receptor complex provides strong support for the contention that the two-pathway mechanism also persists in this complex at low pH and is hence likely to be operative in vivo.

Chlorides↗
PubMed1995

Acute renal failure due to ofloxacin.

Fluoroquinolone antibiotics have rarely been associated with renal failure (1). However, temafloxacin, a member of this drug class, was voluntarily withdrawn from the U.S. market in 1992 after reports of renal failure and other adverse reactions (2). In this article, we report one of the first published cases of renal failure resulting from the administration of ofloxacin (Floxin, Ortho Pharmaceutical Corporation), one of the newest fluoroquinolone antibiotics.

Acute Kidney Injury↗
PubMed1993

Felodipine and isradipine: new calcium-channel-blocking agents for the treatment of hypertension.

The chemistry, pharmacology, pharmacokinetics, clinical uses, adverse effects, and dosage of felodipine and isradipine are reviewed. Felodipine and isradipine are new calcium-channel-blocking agents with FDA-approved labeling for use in the treatment of essential hypertension. Both agents are members of the dihydropyridine class of calcium antagonists, which also includes nifedipine and nicardipine. Like those agents, felodipine and isradipine affect blood pressure by producing peripheral vasodilation. Felodipine and isradipine undergo extensive first-pass metabolism; their bioavailabilities are approximately 15% and 17%, respectively. The drugs are highly protein bound but do not affect serum digoxin concentrations. Anticonvulsants may reduce the elimination half-life of felodipine. Felodipine and isradipine are effective antihypertensive agents when used alone or in combination with beta blockers or diuretics. Both agents have shown some benefit in the treatment of angina pectoris in limited studies. Clinical data do not support the use of either agent for the treatment of congestive heart failure or Raynaud's phenomenon. Felodipine and isradipine have similar adverse-effect profiles, and their adverse effects resemble those of other agents in the class. Common adverse effects are peripheral edema and increased heart rate. The initial dosage of isradipine for the treatment of hypertension is 2.5 mg twice daily. Felodipine should be started at a dosage of 5 mg once daily. Felodipine and isradipine are effective antihypertensive drugs but have not demonstrated clear advantages over other dihydropyridine calcium-channel blockers.

Angina Pectoris↗
PubMedDate not supplied

Regression of metastatic breast cancer in a patient treated with the anti-angiogenic drug TNP-470.

BACKGROUND: Solid tumors in general, and breast cancer in particular, depend on angiogenesis to grow and metastasize. Multiple agents have been developed in order to inhibit this phenomenon of tumor-induced angiogenesis. TNP-470 is one of the most potent of these drugs. We report here a case of regression of metastatic lesions from breast cancer due to the administration of the anti-angiogenic drug TNP-470. METHODS: A 44-year-old woman with a history of stage 2 breast cancer developed metastases at four sites: eye, lung, liver, and bone. She had been treated with radiation, megace, adriamycin, cytoxan, and 5-fluorouracil with disease stabilization. After she completed her radiation and chemotherapy, she was started on TNP-470. RESULTS: In response to TNP-470, her disease showed a partial response at the three-month follow-up and stabilization at the five-month follow-up. There were no side effects, and her quality of life was good. CONCLUSIONS: To our knowledge, this patient is the first reported case of regression of breast cancer metastases as a result of treatment with TNP-470. Anti-angiogenic drugs hold promise for the future therapy of breast cancer, and possibly of many other solid tumors as well.

Adult↗
PubMedDate not supplied

Endothelium-specific expression of an E-selectin promoter recombinant adenoviral vector.

BACKGROUND: E-selectin expression is very low in normal adult blood vessels, but is significantly elevated in newly formed tumor capillaries. We hypothesized that a viral vector which has transcriptional specificity for the tumor vasculature may be a tool for angiogenesis-targeted gene therapy. We therefore designed an adenoviral vector which would only be expressed in cells that transcribe the E-selectin gene. MATERIALS AND METHODS: The E-selectin promoter was inserted into an adenoviral vector driven by the luciferase reporter gene. The resulting AdV-Esel-Luc vector was then used to transduce endothelial cells as well as other cell types, and luciferase activity measured with a luminometric assay. RESULTS: Exposure of transduced endothelial cells to TNF-alpha (tumor necrosis factor-alpha), a known inducer of the E-selectin promoter, generated a 30-fold increase in luciferase expression compared to untreated cells (p = 0.01). Endothelial cells cultured in tumor conditioned media as an in vitro recreation of the tumor environment resulted in even higher induction of luciferase (p = 0.0001). Furthermore, many non-endothelial cell lines expressed minimal levels of luciferase when transduced with the AdV-Esel-Luc vector under identical conditions. CONCLUSIONS: We conclude that the E-selectin promoter can be used in order to confer transcriptional specificity to an adenoviral vector. This transcriptional specificity may in the future enable us to deliver the specific expression of therapeutic genes to the tumor vasculature.

Adenoviridae↗