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Biomedical subjects

R M Petitt

Publications and source records attributed to R M Petitt.

At least 19 recordsLinked to original sources
PubMed1998

Hydroxyurea-induced leg ulceration in 14 patients.

BACKGROUND: Hydroxyurea is an antineoplastic agent commonly used to treat myeloproliferative disorders and other nonneoplastic conditions. OBJECTIVE: To further define the typical features of hydroxyurea-related cutaneous ulcers of the leg. DESIGN: Retrospective, descriptive study of the medical records of patients who developed leg ulcers while receiving hydroxyurea therapy. SETTING: A tertiary care medical center. PATIENTS: Patients with myeloproliferative disorders who were treated with hydroxyurea. RESULTS: 14 patients with extremely painful leg ulcers were identified. The most common ulcer site was the malleoli. Multiple ulcers were seen in 64% of patients. Patients had received hydroxyurea for an average of 6 years before ulcers developed. All ulcers healed after discontinuation of hydroxyurea treatment, and 2 patients developed ulcers after treatment was restarted. CONCLUSION: Hydroxyurea induces painful leg ulcers that are usually difficult to treat and require cessation of hydroxyurea therapy.

Adult↗
PubMed1998

Multiple skin cancers associated with hydroxyurea therapy.

The association of multiple cutaneous cancers and long-term use of hydroxyurea is now being recognized. In this article, we describe the development of multiple skin tumors in two patients who were receiving hydroxyurea therapy. These cases illustrate the late onset of subsequent skin cancers despite discontinuation of therapy. As hydroxyurea continues to have a prominent role in the treatment of myeloproliferative diseases, clinicians must be aware of the increased risk of multiple skin cancers and use preventive and skin cancer screening practices in patients with these diseases.

Basal Cell Carcinoma↗
PubMed1997

The effects of anagrelide on human megakaryocytopoiesis.

Anagrelide, an inhibitor of platelet aggregation, decreases the number of platelets in normal subjects and in patients with myeloproliferative disorders. We describe studies aimed at discovering the general mechanism(s) by which anagrelide acts. We examined three hypotheses: (1) anagrelide shortens platelet survival, (2) anagrelide inhibits the proliferation of megakaryocytic-committed progenitor cells (CFU-M), and (3) anagrelide inhibits maturation of megakaryocytes. We observed that anagrelide did not shorten platelet survival. Proliferation of CFU-M in vivo was not affected by anagrelide, although high concentrations of anagrelide inhibited CFU-M in vitro. In-vivo and in-vitro anagrelide altered the maturation of megakaryocytes, causing a decrease in their size and changing other morphometric features. We conclude that anagrelide decreases the number of platelets primarily by interfering with the maturation of megakaryocytes.

Adult↗
PubMed1997

Anagrelide as a new platelet-lowering agent in essential thrombocythemia: mechanism of actin, efficacy, toxicity, current indications.

Anagrelide is an oral imidazoquinazoline agent with an anti-cyclic AMP phosphodiesterase activity and inhibits platelet aggregation in both humans and animals. In addition, it has in humans a species-specific platelet-lowering activity observed at dose levels lower than those required to inhibit platelet aggregation. Because of this, the drug has been tested in patients with clonal thrombocytosis and has been shown to have potent platelet-reducing activity in essential thrombocythemia (ET) and related disorders. The mechanism of action may involve the drug's interference with megakaryocyte maturation. More than 90% of patients with ET respond to anagrelide regardless of the presence or absence of previous therapy. The responses are durable with a median maintenance dose of approximately 2 to 2.5 mg/day. Side effects are related mostly to the drug's direct vasodilating and positive inotropic effects and include headache, fluid retention, tachycardia, and arryhthmias. The place of anagrelide therapy in the current management of patients with ET is discussed.

Animals↗
PubMed1996

Measurement of blood volume and red cell mass: re-examination of 51Cr and 125I methods.

Comparison of results of red cell mass (RCM) measurement by 51Cr and 125I methods in 119 patients showed virtual equivalence. Both methods have an acceptable coefficient of variation (CV) that is < 5%. The 125I method is simpler and much less expensive. Unrealistically narrow "normal ranges" for RCM are likely to lead to misdiagnosis of polycythemia vera. Upper normal limits of 39 mL/kg (males) and 32 mL/kg (females) are consistent with originally published data in normal persons; use of these limits as criteria would reduce the risk of misdiagnosis. No cases of "stress erythrocytosis" or Gaisbock Syndrome were encountered among the 119 cases reviewed.

Blood Volume↗
PubMed1995

Outcome analysis of 34 pregnancies in women with essential thrombocythemia.

OBJECTIVE: To evaluate the clinical impact of essential thrombocythemia on the outcome of pregnancy or vice versa. DESIGN: A retrospective study. SETTING: All patients were seen at our tertiary referral center, and most were followed up by their local physicians. PATIENTS: From 1975 through 1991, 73 women younger than 50 years with essential thrombocythemia were seen at our institution. All patients were followed up through patient or physician contact. A detailed obstetric history, including peripartum complications and management, was obtained. RESULTS: Among the 73 women, 34 pregnancies occurred in 18 patients. There were two uncomplicated elective abortions and one ectopic pregnancy. Of the 31 other pregnancies, 17 (55%) resulted in live birth and 14 (45%) ended in spontaneous abortion (all but two in the first trimester). Abortion could not be predicted from history of disease complications before or during pregnancy or by the presence or absence of specific therapy during pregnancy. Preconception platelet counts in women whose pregnancies resulted in live birth were similar to those of women whose pregnancies ended in abortion. Other complications during pregnancy were rare. CONCLUSIONS: Patients with essential thrombocythemia have an increased risk of first-trimester abortion, which does not appear to be predictable or influenced by therapy. However, most patients are able to carry pregnancies to term with little or no risk of obstetric or thrombohemorrhagic complications during or after delivery. Overall, specific therapy during pregnancy did not appear to modify the clinical outcome, and the benefit of platelet apheresis during delivery could not be substantiated.

Adult↗
PubMed1991

Essential thrombocythemia in young adults.

Essential thrombocythemia is typically a disorder of adults in the sixth or seventh decade of life and is characterized by frequent thrombohemorrhagic complications. In young patients, the optimal management of complications is controversial. We studied 56 young adults (33 female and 23 male patients) with a diagnosis of essential thrombocythemia. The mean duration of follow-up was 4.68 years. The mean platelet count at diagnosis was 1,328,000/mm3. Platelet aggregation studies in 21 patients demonstrated hypoaggregation to epinephrine; spontaneous platelet aggregation was present in 4. At diagnosis, 39 patients were asymptomatic, and thrombocytosis was discovered incidentally. Throughout follow-up (up to 20 years), 24 patients remained asymptomatic. Thrombotic complications developed in 24 patients; they were life-threatening in only 3. The most common vaso-occlusive symptoms were migraine headache (in 12 patients) and erythromelalgia (in 3). Minor hemorrhagic complications occurred in six patients, and none was life-threatening. Serious complications (one cerebral and two myocardial infarctions) occurred in three patients, all of whom recovered. Two deaths occurred, neither of which was attributable to essential thrombocythemia. The treatment regimens used were chemotherapy in 9 patients, antiaggregating agents in 7, radioactive phosphorus in 1, the newer platelet-lowering agent anagrelide in 10, and only observation in 29. No treatment-related acute leukemias developed. This series of young patients with essential thrombocythemia, the largest to date, demonstrates a low incidence of life-threatening complications and a favorable long-term prognosis. Therapeutic recommendations should remain conservative, and potential leukemogens should be avoided unless serious complications develop. Anagrelide may be useful in young patients with thrombocythemia who are symptomatic.

Adolescent↗
PubMed1991

Prognostic significance of computed tomography of the brain in thrombotic thrombocytopenic purpura.

We studied the prognostic value of computed tomography (CT) of the brain for neurologic morbidity in patients with thrombotic thrombocytopenic purpura. On review of Mayo Clinic records for 1975 through 1985, we found 32 patients with thrombotic thrombocytopenic purpura, 20 of whom had undergone CT of the brain during their hospitalization. Despite major neurologic symptoms and signs, normal CT findings were associated with complete neurologic recovery. Seventy percent of patients with normal results of CT of the brain recovered and had no neurologic deficits, whereas 80% of patients with CT abnormalities died or had permanent neurologic sequelae. A review of the literature supports these conclusions. Thus, we suggest that CT of the brain be done in any patient with thrombotic thrombocytopenic purpura and neurologic deficits. Regardless of the severity of neurologic involvement, normal CT findings should encourage continued vigorous treatment of the patient because a normal scan supports the possibility of full clinical recovery.

Adolescent↗
PubMed1991

Chromosome studies in 104 patients with polycythemia vera.

Chromosome studies were done in 104 patients with various stages of polycythemia vera (PV): 10 had leukemia-myelodysplastic syndrome, 28 had post-PV with myeloid metaplasia (PPVMM), 12 had PV with myelofibrosis, and 54 had PV. Chromosome studies were successful in 86 patients, 37 (43%) of whom had a chromosome abnormality. At diagnosis, 4 of 28 patients (14%) had an abnormal clone; the incidence was 78% in PPVMM and 100% in leukemia-myelodysplastic syndrome. Among the 63 patients with successful chromosome studies during the first 10 years of disease, 27% had an abnormal clone. In contrast, of the 23 patients who had the disease for more than 10 years, 87% had an abnormal clone. Chromosome abnormalities were found in 11 of the 60 patients who either were untreated or underwent only phlebotomy and in 26 of the 44 patients who were treated with myelosuppressive agents. Trisomy 8, +9, and 20q- were found in some patients early during the course of their disease and also among untreated patients. These chromosome abnormalities seem to be related to the natural course of PV rather than to therapy. Patients with a chromosomally abnormal clone at the time of diagnosis of PV had a poorer survival than did those with only normal metaphases. Cytogenetic results did not predict evolution of the disease, but they did provide clues to hematologic phenotype, duration of the disease, and consequences of myelosuppressive therapy.

Acute Disease↗
PubMed1989

Adult-onset cyclic bicytopenia: a case report and review of treatment of cyclic hematopoiesis.

A unique case of adult-onset synchronous cyclic neutropenia and thrombocytopenia occurring at six-week intervals is presented. Periods of cytopenia were associated with fever, myalgias, gastrointestinal symptoms, and mild mucocutaneous bleeding. Alternate-day steroid treatment failed to correct the periodic fluctuations in peripheral blood counts but ameliorated symptoms during cytopenia. The treatment of cyclic hematopoiesis is reviewed.

Agranulocytosis↗
PubMed1988

Anagrelide: a new drug for treating thrombocytosis.

Anagrelide is a member of the imidazo (2,1-b) quinazolin-2-one series of compounds, with a powerful antiaggregating effect on platelets. During studies in humans, anagrelide in small doses has produced thrombocytopenia. We therefore evaluated it in the treatment of thrombocytosis, and to date, platelet levels in 15 of 17 patients with primary thrombocythemia, 2 patients with polycythemia vera and thrombocytosis, and 1 patient with chronic granulocytic leukemia and thrombocytosis have been well controlled with the use of this agent. Induction doses of 1.0 to 1.5 mg given orally every six hours have produced a decrease in the platelet count, starting on day 5 and reaching a normal level by day 12. Side effects of anagrelide have been minimal. Maintenance therapy with 1.5 to 4.0 mg a day has continued to control the platelet count in patients for up to 28 months. This new agent appears promising in the treatment of thrombocytosis in patients with chronic myeloproliferative disease.

Adult↗
PubMed1987

Autosomal dominant familial Mediterranean fever-like syndrome with amyloidosis.

We report a pedigree in which a syndrome that resembled familial Mediterranean fever occurred in four family members over three successive generations. All four patients had systemic amyloidosis. Typically, patients with familial Mediterranean fever show an autosomal recessive inheritance pattern. The disorder commonly afflicts Sephardic Jews, Arabs, and persons of Turkish descent. Colchicine therapy dramatically reduces the attack rate of serositis. The family described herein is unique because of their European ethnicity and the autosomal dominant inheritance pattern. Unlike typical familial Mediterranean fever, colchicine had no influence on the attacks and did not prevent amyloidosis in the three patients who received this treatment.

Adult↗
PubMed1986

Paroxysmal nocturnal hemoglobinuria: erythrocyte acetylcholinesterase deficit analyzed by immunoassay and fluorescence-activated sorting.

An immunodisplacement assay based on a specific, solid-phase monoclonal antibody was designed to measure acetylcholinesterase in tissue extracts. Sample enzyme content was determined from the competitive reduction of binding of a purified acetylcholinesterase standard, with a detection limit of 5 ng or less. Washed erythrocyte membranes from six normal subjects averaged 1.8 units of acetylcholinesterase activity and 0.45 microgram of acetylcholinesterase content per milligram of total protein. Enzyme activity and content in samples from three patients with paroxysmal nocturnal hemoglobinuria (PNH) were reduced approximately in parallel, by as much as 70%. The residual cholinesterase had almost the same homospecific activity as the normal enzyme and was bound with equivalent affinity by six different antibodies. Therefore, the cholinesterase defect was dominated by enzyme loss rather than by structural abnormalities affecting enzyme function. Fluorescence-activated sorting of antibody-labeled erythrocytes revealed a bimodal population distribution. Up to 66% of the PNH cells lacked cholinesterase, and the rest had a near-normal enzyme content. Inasmuch as enzyme-deficient cells represent the complement-sensitive population, cell sorting may help in assessing clinical status and, perhaps, in developing new therapeutic modalities for PNH.

Acetylcholinesterase↗
PubMed1982

Treatment of thrombotic thrombocytopenic purpura with plasma exchange, antiplatelet agents, corticosteroid, and plasma infusion: Mayo Clinic experience.

Ten patients with thrombocytopenia (TTP) were treated recently in our institution with plasma exchange (PE), steroids, and antiplatelet drugs. Additionally, fresh frozen plasma (FFP) was administered to nine patients, with folic acid given to eight patients. After 13 to 25 months of follow-up, we found that four patients achieved and remained in remission after initial treatment. Three patients had four relapses, which developed while they were taking antiplatelet therapy, and which were treated successfully with FFP alone, or with PE in addition to FFP. Four patients suffered major neurological or renal damage during their presentation or initial treatment. One of these patients died during his initial hospitalization. Another patient died 7 months after initial treatment. After analyzing this experience, we have concluded that antiplatelet drugs or corticosteroid should be used as the sole initial treatment most cautiously. The relative importance of the exchange process, per se, versus plasma infusion cannot be inferred from our observations, but plasma exchange with FFP appears to have had a real impact on recovery.

Adrenal Cortex Hormones↗
PubMed1981

Resistance to therapy of acute leukemia developing in the course of polycythemia vera.

Thirteen patients in whom acute leukemia developed in the course of polycythemia vera were initially treated with vincristine and prednisone in an attempt at remission induction. None responded, and four died during this initial course of therapy. Induction was then attempted in the nine survivors, using cytosine arabinoside and adriamycin. Only one complete remission of 38 weeks and one partial remission were achieved, while median survival was 32 days. Poor results may reflect both the intrinsic biologic properties of the acute leukemia occurring in this setting and the advanced age of the patients.

Acute Disease↗