Search PubMed⌕ Search

Biomedical subjects

G Peterson

Publications and source records attributed to G Peterson.

At least 55 records · Page 3Linked to original sources
PubMed1998

Paclitaxel administration to gynecologic cancer patients with major cardiac risk factors.

PURPOSE: To examine the safety of administering paclitaxel to patients with preexisting significant cardiac risk factors. PATIENTS AND METHODS: The medical records of gynecologic cancer patients with major cardiac risk factors who had been treated with paclitaxel (single-agent or combination regimen with cisplatin or carboplatin) at The Cleveland Clinic Foundation from 1993 through February 1998 were examined to determine the acute toxicity of therapy. RESULTS: A total of 15 patients were found who met these criteria, of whom none were found to have suffered a worsening of cardiac function following treatment with paclitaxel. A single patient developed a severe paclitaxel-associated hypersensitivity reaction, but no cardiac sequela. CONCLUSION: This series suggests that paclitaxel can be safely administered as a single agent or in a combination regimen with a platinum agent to some patients with significant cardiac risk factors, such as those associated with ischemic heart disease. However, since few patients had baseline severe conduction defects before paclitaxel treatment, the safety of this drug in this clinical setting remains to be determined.

Aged↗
PubMed1998

Ninety-six-hour infusional paclitaxel as salvage therapy of ovarian cancer patients previously failing treatment with 3-hour or 24-hour paclitaxel infusion regimens.

PURPOSE: To test the hypothesis that prolonged infusion of paclitaxel (96 hours) might overcome resistance to shorter infusion schedules (3 or 24 hours) in ovarian cancer. PATIENTS AND METHODS: A total of 30 patients with advanced ovarian cancer (24 patients), primary carcinoma of the peritoneum (four patients), or fallopian tube cancer (two patients) who previously had received paclitaxel administered on either a 3-hour or 24-hour schedule were treated with the agent delivered as a 96-hour infusion (30 to 35 mg/m2/d x 4 days) on an every 3-week program. RESULTS: Although the regimen generally was well tolerated, no objective responses were observed. CONCLUSION: In patients with ovarian cancer who have shown resistance to shorter paclitaxel infusion schedules, ninety-six hour infusional paclitaxel is an inactive treatment strategy. This makes it less likely that protracted infusion of paclitaxel will improve outcome when used as part of primary therapy of ovarian cancer. An ongoing randomized study will answer that question.

Adult↗
PubMed1998

Vasectomy and human immunodeficiency virus type 1 in semen.

PURPOSE: Human immunodeficiency virus type 1 (HIV) is cultured more often from seminal cells than seminal plasma. Because vasectomy causes dramatic reductions in seminal cells and also eliminates secretions from proximal sites in the male reproductive tract, vasectomy may change the potential infectiousness of semen. MATERIALS AND METHODS: We used polymerase chain reaction (PCR) assays to measure HIV ribonucleic acid (RNA) in seminal plasma and HIV deoxyribonucleic acid (DNA) in seminal cells from 46 asymptomatic, seropositive men before and after vasectomy. RESULTS: HIV RNA levels in semen correlated only weakly with blood levels (r = 0.22, p = 0.03). Of 183 semen specimens assayed for cell-free HIV RNA and proviral DNA 37 (20%) were positive for HIV RNA only, 41 (22%) were positive for HIV DNA only, and 18 (10%) were positive for RNA and DNA. Thus, detection of HIV RNA in seminal plasma was not associated with detection of HIV DNA in seminal cells. HIV RNA was present in 23 of 82 specimens (28%) (mean 2.87 log copies/ml.) before vasectomy and in 38 of 121 specimens (31%) after vasectomy (mean 2.81 log copies/ml.). CONCLUSIONS: These findings suggest that direct measurement of HIV levels in semen is necessary to assess the potential for sexual transmission, most cell-free HIV in seminal plasma arises distal to the vas deferens, and vasectomy may have minimal impact on the infectiousness of HIV seropositive men on sexual partners.

Adult↗
PubMed1997

Continued chemosensitivity to cisplatin/carboplatin in ovarian carcinoma despite treatment with multiple prior platinum-based regimens.

While it is well recognized that individuals with ovarian cancer who have previously responded to platinum-based therapy can achieve a second response to cisplatin or carboplatin at the time of relapse, limited data exist in the oncologic literature regarding the number of times this process can be repeated. We briefly report here three patients with ovarian cancer currently being cared for in the Gynecologic Oncology program of the Cleveland Clinic Foundation who have achieved four (1 patient) or five (2 patients) separate clinical responses to cisplatin or carboplatin-based chemotherapy and have survived >4 years since the date of first relapse. This experience emphasizes the point that platinum resistance cannot be defined based on total treatment courses or the number of prior platinum-based regimens delivered, but only by objective evidence of failure of the drugs in an individual patient.

Aged↗
PubMed1997

Low-dose intravenous ondansetron (8 mg) plus dexamethasone: an effective regimen for the control of carboplatin-induced emesis.

Twenty-nine patients with gynecologic malignancies were treated with a fixed low dose of intravenous ondansetron (8 mg) plus dexamethasone (20 mg) in an effort to develop an effective and less expensive antiemetic regimen for the control of carboplatin-induced emesis. Twenty-six (90%) of the women participating in this trial experienced complete control of both acute nausea and vomiting (developing within the first 24 h after chemotherapy administration), while 27 (93%) patients exhibited either complete or major control (< or = 2 episodes of vomiting, < or = 5 episodes of retching, minimal interference with eating) of emesis. On the basis of our experience in this trial, we conclude that the combination of low dose (8 mg) intravenous ondansetron plus dexamethasone is a well-tolerated and highly cost-effective antiemetic strategy for individuals receiving carboplatin-based chemotherapy.

Adult↗
PubMed1997

Carboplatin plus paclitaxel in the treatment of gynecologic malignancies: the Cleveland Clinic experience.

To examine the toxicity profile and antineoplastic activity of carboplatin (area under the concentration-time curve of 4 to 7.5) plus 3-hour infusional paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) (135 or 175 mg/m2) in women with advanced gynecologic malignancies, we retrospectively reviewed the experience of the Gynecologic Cancer Program at The Cleveland Clinic with this combination chemotherapy regimen. To date, 92 patients (median age, 67 years) have received a total of 460 courses (median number per patient, six) of this two-drug combination. The initial paclitaxel dose was 175 mg/m2 and the carboplatin area under the concentration-time curve was > or = 5 in 72% and 73% of patients, respectively. The major toxicity was neutropenia (grade 4 in 9% of patients), resulting in two febrile episodes and a single septic death. Grade 4 thrombocytopenia and grade 3 peripheral neuropathy were noted in one and two patients, respectively. Twelve patients (13%) experienced at least one episode of paclitaxel-associated hypersensitivity, but all were able to continue with the treatment program. Of the 62 patients with ovarian cancer or primary peritoneal carcinoma with carbohydrate antigen-125 levels > or = 60 U/mL before the initiation of chemotherapy, 74% exhibited a > or = 90% decline in the tumor marker following treatment. We conclude that the combination of carboplatin and 3-hour infusional paclitaxel can be administered in the outpatient setting with a highly acceptable toxicity profile and with major activity in patients with ovarian cancer and primary carcinoma of the peritoneum.

Adult↗
PubMed1996

Control of carboplatin-induced emesis with a fixed low dose of granisetron (0.5 mg) plus dexamethasone.

In an effort to develop a cost-effective antiemetic regimen for carboplatin-based chemotherapy, we examined a fixed (0.5 mg) low dose of granisetron (a new 5-HT3 (serotonin) antagonist) plus dexamethasone (20 mg) in 23 patients with gynecologic malignancies receiving this antineoplastic drug. Nineteen (83%) patients experienced complete control of acute emesis (nausea and vomiting) while 22 (96%) individuals demonstrated complete or major control (< or = 2 episodes of vomiting, < or = 5 episodes of retching, minimal interference with eating) of emetic events. We conclude that this fixed low-dose granisetron plus dexamethasone regimen is a safe, convenient, and cost-effective antiemetic program for individuals receiving carboplatin-based chemotherapy.

Adult↗
PubMed1996

Paclitaxel delivered as a 3-hr infusion with cisplatin in patients with gynecologic cancers: unexpected incidence of neurotoxicity.

In an effort to develop a paclitaxel plus cisplatin combination chemotherapy regimen which can be easily employed in the outpatient setting, 38 patients (median age, 59; range, 39-72) with gynecological malignancies (20 ovarian; 6 primary peritoneal; 12 endometrial) seen at the Cleveland Clinic Foundation from June 1993 to May 1995 were administered 170 cycles of paclitaxel (135 or 175 mg/m2) over 3 hr followed by cisplatin (starting dose 75 mg/ m2). Of the 33 patients with elevated CA-125 levels prior to the initiation of chemotherapy, all experienced > 50% decreases in this antigen level, while 23/33 (70%) had > 90% reductions. In general, nonneurologic side effects were mild in severity and easily manageable. Unfortunately, 71% of the patients developed neurologic toxicity, with one-fifth of the treated population experiencing severe neurotoxic side effects (grade 3-4). We conclude that paclitaxel administered over 3 hr at a dose of 135 or 175 mg/m2, followed by cisplatin (75 mg/m2), is a highly active regimen in gynecologic malignancies. Unfortunately, in our experience, the incidence and severity of neurotoxicity with this regimen is considerably greater than that reported with paclitaxel administered over 24 hr in combination with cisplatin. As a result of the observed toxicity profile, this drug delivery schedule for cisplatin and paclitaxel cannot be recommended for general clinical use.

Adult↗
PubMed1996

Continuous subcutaneous administration of mesna to prevent ifosfamide-induced hemorrhagic cystitis.

Hemorrhagic cystitis is a major potential toxicity of ifosfamide that can be prevented by administering mesna along with the cytotoxic agent. Mesna is generally administered by the intravenous route, although experience with oral delivery of the drug has increased. The continuous subcutaneous administration of mesna has the advantage of not requiring intravenous access. In addition, subcutaneous delivery of the neutralizing agent will not be associated with the risk of inadequate urinary mesna concentrations, such as in a patient taking oral mesna who experiences severe ifosfamide-induced emesis and is unable to absorb the drug. Limited clinical experience with continuous subcutaneous mesna administration suggests it is a safe, practical, and economic method of drug delivery that permits ifosfamide to be administered successfully in the outpatient setting.

Administration, Oral↗
PubMed1996

Pitfalls and outcomes from accelerated wear testing of mechanical heart valves.

In 1990 Sorin Biomedica introduced a new bileaflet heart valve called the Bicarbon valve. This design was reported to eliminate wear in the hinge mechanism. Clinical quality Sorin Bicarbon, CarboMedics, St. Jude Medical, Duromedics and Jyros valves were obtained to test this claim and to compare the wear in the pivot of this new valve to other available heart valves. The valves were visually inspected then subjected to 4,000 cycles at a physiological beat rate in vitro. The valves were re-inspected then subjected to 400 million cycles in a Reul type accelerated wear tester. Scanning electron microscope photographs were taken of all contact areas at 40, 80, 120, 160, 200, 240, 280 and 400 million cycles. Wear marks on the inflow side of the Sorin, CarboMedics and St. Jude leaflets were measured and compared. Orifice wear was not quantified because of difficulty with measuring inside complex depressions. After 4,000 cycles of testing at a physiological beat rate the CarboFilmTM coating on the Sorin orifice showed signs of erosion. The other valve components only exhibited minor burnishing after 4,000 cycles. Following completion of 400 million cycles in an accelerated wear tester, approximately ten years in vivo, all valves showed significant wear. The inflow face of the pivot on the Sorin Bicarbon leaflets exhibited the deepest wear marks. The CarboFilm coating on the Sorin Bicarbon orifices was removed from most areas of leaflet contact. The transition between the remaining coating and the eroded areas created a rough edge. The tips of the Sorin leaflets contacted the bottom of the orifice pivot, in contrast to the St. Jude Medical and CarboMedics designs, which had minimal contact between the leaflet and the orifice.

Biocompatible Materials↗
PubMed1996

Genistein inhibits both estrogen and growth factor-stimulated proliferation of human breast cancer cells.

Genistein is a naturally occurring dietary protein tyrosine kinase (PTK) inhibitor that is hypothesized to be responsible for the lower rate of breast cancer observed in Asian women consuming soy. Although genistein is a potent in vitro PTK inhibitor, its mechanism of action in vivo is not known. In vivo, breast cancer growth is regulated by estrogens and peptide growth factors, such as epidermal growth factor (EGF), the receptor of which has intrinsic PTK activity. Therefore, genistein may block mammary epithelial cell growth by interfering with signal transduction events stimulated by estradiol or growth factors. The effect of genistein, related isoflavones, and other tyrosine kinase inhibitors on fetal bovine serum-, estradiol-, and EGF-stimulated cell growth and signal transduction pathways was examined in five human breast cancer cell lines. Genistein inhibited the growth of these cells by each of the growth stimuli with IC50 values ranging from 2.6 to over 20 micrograms/ml. Growth inhibition by genistein was cytostatic and reversible at IC50 concentrations. Related isoflavones were less potent growth inhibitors than genistein, whereas the synthetic PTK inhibitor tyrphostin A25 was an equally potent growth inhibitor. The mechanism of genistein growth inhibition in human breast cancer cells did not depend on the presence of functional estrogen receptor signaling pathways or on inhibition of EGF-receptor PTK activity. Furthermore, genistein (< or = 20 micrograms/ml) did not decrease constitutive or EGF-induced tyrosine phosphorylation as determined by Western blotting with antiphosphotyrosine antibodies. These data suggest that although genistein inhibits the growth of breast cancer cells in culture, it does so without gross inhibition of PTK activity.

Animals↗
PubMed1995

Improved outcome by identification of high-risk nonocclusive mesenteric ischemia, aggressive reexploration, and delayed anastomosis.

BACKGROUND: The factors associated with outcome of patients with nonocclusive mesenteric ischemia are poorly defined. METHODS: Over a 7-year period, 34 consecutive patients with nonocclusive mesenteric ischemia were identified. RESULTS: The mean age of the study patients was 63 years (range 31 to 94); 21 of 34 (62%) were men. The mean delay in diagnosis was 31 hours (range 7 hours to 6 days). Seven of 34 (21%) underwent preoperative visceral arteriography. Two of these 7 required surgery, and both died as a result of intestinal infarction. The remaining 27 had the diagnosis made at celiotomy. Among the 29 who were explored, 16 of 29 (55%) had intestinal infarction. Twenty-one of 29 (72%) had segmental bowel injury whereas 8 of 29 (28%) had massive injury. Among those with segmental infarction, primary anastomosis was performed in 12 of 21 patients (57%); 5 of the 12 (42%) died. Nine of 21 patients (43%) underwent delayed anastomosis; 2 of the 9 (22%) died. No patient with massive injury underwent primary anastomosis. Second-look laparotomy was performed on 22 of 29 (76%). Eleven of those 22 (50%) had a further bowel resection. Overall, 16 of 29 (55%) who underwent surgery for nonocclusive mesenteric ischemia are alive. CONCLUSIONS: Improved survival from nonocclusive mesenteric ischemia is dependent upon the identification of high-risk groups, aggressive reexploration, and delayed intestinal anastomosis.

Acute Disease↗
PubMed1995

Evaluation of the biochemical targets of genistein in tumor cells.

Although data from epidemiological studies and cancer models suggest that genistein plays an important role in cancer prevention, the biochemical target(s) of genistein action is (are) not known. Genistein is a potent in vitro inhibitor of protein tyrosine kinase (PTK) activity, especially that of the epidermal growth factor receptor (EGF-R), having little effect on serine/threonine kinases. This led to the suggestion that genistein might exert its anti-cancer effects through inhibiting the activity of EGF-R PTK, or other crucial PTK's in vivo. Subsequent studies on intact tumor cell lines demonstrated that EGF-R and other growth factor receptors are able to transmit mitogenic signals in the presence of genistein. In fact, it is difficult to detect decreases in the tyrosine phosphorylation of discrete proteins after genistein treatment. Other mechanisms for the effect of genistein have been suggested from in vitro and cell culture data. Genistein not only inhibits the activity of purified topoisomerase II in vitro, but also leads to the accumulation of protein-associated single strand breaks in whole cells. Genistein also inhibits the production of reactive oxygen species which may lead to tissue damage and DNA modification. Additionally, genistein acts as a weak estrogen, modifies cellular differentiation programs, inhibits angiogenesis. modulates cell cycle events and may precipitate apoptosis. However, few of the above mechanisms in tumor cells are sensitive to the physiological serum concentrations of genistein (< 18.5 mumol/L, or < 5 micrograms/mL). Primary, nontransformed human mammary epithelial cells, which have a much greater sensitivity to genistein, would be a better system for the study of these mechanisms.

Animals↗