Reassessing the principles of electrical stimulation.

The mechanisms by which electrical stimulation (ES) of carcasses can be used to modulate meat quality are reviewed. Evidence to support an effect of ES on tenderness (and other meat quality attributes) based solely on changes in the pH/temperature profile within carcass muscles are presented. The interactions between electrical parameters and the contraction responses of carcass muscles are described to provide generalised principles to guide the design of electrical stimulation technology. The commercial risks to meat quality of inappropriate use of electrical stimulation, particularly excessive stimulation to produce PSE-like conditions, are considered.

Resource pulses, species interactions, and diversity maintenance in arid and semi-arid environments.

Arid environments are characterized by limited and variable rainfall that supplies resources in pulses. Resource pulsing is a special form of environmental variation, and the general theory of coexistence in variable environments suggests specific mechanisms by which rainfall variability might contribute to the maintenance of high species diversity in arid ecosystems. In this review, we discuss physiological, morphological, and life-history traits that facilitate plant survival and growth in strongly water-limited variable environments, outlining how species differences in these traits may promote diversity. Our analysis emphasizes that the variability of pulsed environments does not reduce the importance of species interactions in structuring communities, but instead provides axes of ecological differentiation between species that facilitate their coexistence. Pulses of rainfall also influence higher trophic levels and entire food webs. Better understanding of how rainfall affects the diversity, species composition, and dynamics of arid environments can contribute to solving environmental problems stemming from land use and global climate change.

Infant sleep: resident recommendations and socioeconomic status differences in patient practices.

BACKGROUND: Although much research has focused on parental report of infant sleep position since the 1992 American Academy of Pediatrics (AAP) recommendation for non-prone placement, few studies have examined physician recommendations regarding infant sleep. This study examined differences between resident recommendations for infant sleep position and cosleeping (bed sharing) and parental report of practice. We also assessed socioeconomic differences in parent practice, awareness, and acceptability of AAP guidelines. METHODS: We conducted a telephone survey of parents of 2-, 4-, 8-, and 12-month-old infants from two family practice centers. All 27 residents at both centers completed a paper and pencil survey. RESULTS: Resident recommendations and parental practices differed significantly for both sleep positioning and cosleeping. Parents of 165 infants participated, revealing that higher socioeconomic families were more aware of compliant with, and more accepting of AAP recommendations for supine positioning. CONCLUSIONS: Parents consistently report that their physician or nurse is the primary source of information for infant sleep. Results of this study, however, indicate significant differences between physician recommendation and parental practice and acceptability of AAP guidelines. Physicians need to continue to discuss this information past the newborn period.

Anaphylactoid reactions to methotrexate.

BACKGROUND: Methotrexate is a chemotherapeutic agent frequently utilized for the treatment of malignant, rheumatic, and pulmonary diseases. Although this agent has been extensively used for more than 45 years, there are few reports of immediate systemic hypersensitivity reactions. The reported immediate reactions include anaphylaxis, urticaria, and hepatitis. However, these reactions have been reported to occur only after some prior exposure to methotrexate. No immediate hypersensitivity reactions to methotrexate have been reported during the initial exposure. We describe two patients who developed immediate systemic hypersensitivity reactions during the initial administration of methotrexate. METHODS: The clinical outcomes of two patients treated by the Hematology/Oncology department at a tertiary care military medical center are described. The National Library of Medicine in Bethesda, Maryland, was electronically searched for the literature review. RESULTS: Patient 1, a 30-year-old male with localized high grade osteosarcoma of the left distal femur, developed generalized pruritus, urticaria, angioedema, and pharyngeal edema within 10 minutes of receiving the initial administration of intravenous high-dose methotrexate. No other pharmaceutical agents, such as antiemetics, were found to cause symptoms on rechallenge. The severity of this reaction precluded continuation of methotrexate therapy. Patient 2, a 23-year-old male with localized high grade osteosarcoma of the right distal tibia, developed pruritus and urticaria within 30 minutes of receiving the initial administration of intravenous high dose methotrexate. This patient, like most patients with immediate hypersensitivity reactions to methotrexate, developed recurrent symptoms during rechallenge of this agent despite prophylactic premedication. CONCLUSIONS: Unlike prior reports in our literature, our cases demonstrate that anaphylactoid reactions can occur during the initial exposure to methotrexate. Clinicians must be prepared to treat potentially life-threatening reactions with both the initial and subsequent doses of methotrexate.

Unexplained bleeding associated with central venous catheter care.

Significant bleeding associated with inadvertent heparin overdosage may occur in children with cancer and indwelling central venous catheters. The etiology of such bleeding, as described in a child with Wilms' tumor, may not be immediately apparent. It is imperative that the proper techniques for maintenance and anticoagulation of the catheter be ascertained.

Long-term results in the treatment of acute nonlymphocytic leukemia: a Pediatric Oncology Group Study.

Complete remission (CR), 5-year remission duration (RD), and overall 5-year survival rates are 74%, 28% and 25%, respectively, for previously untreated children with acute nonlymphocytic leukemia diagnosed between 1977 and 1981, following induction therapy with vincristine, doxorubicin and prednisone (VAP), consolidation therapy with 6-thioguanine, cytosine arabinoside (TA) and cyclophosphamide/vincristine/cytosine arabinoside/prednisone (COAP), and maintenance therapy of alternating TA and COAP with or without VAP pulses. Approximately 20% are free of their disease for more than 5 years. High white blood cell counts (WBC) at diagnosis and M3 and M6 morphology were associated with lower CR rates, while M5 morphology was associated with higher CR rates. Patients with M1 morphology had shorter remission duration as compared to those with M4 or M5 morphology. Low WBC and age between 2 and 10 years at diagnosis were associated with longer remission durations and survival. Patients with M4 morphology also survived longer. The observed CR rates are comparable to other studies initiated at the same time as this study but survival is less than those reported more recently. Low WBC at diagnosis and M4/M5 morphology may identify relatively favorable prognostic groups.

Phase II study demonstrating failure of both a five-drug continuous-therapy regimen and a two-drug pulse-therapy regimen in the treatment of metastatic neuroblastoma: Southwest Oncology Group Study 822.

Twenty-six children greater than 1 year of age with previously untreated stage IV neuroblastoma were randomized to receive either a five-drug regimen (prednisone, cyclophosphamide, actinomycin D, vincristine, and daunorubicin) or a two-drug regimen (cyclophosphamide and vincristine). Complete response rates were 6% and 9% for the five-drug and the two-drug regimens respectively. Partial response rates were 13% and 27% for the five-drug and the two-drug regimens respectively. The mean duration of the seven responses was 9 months, and all 26 patients had died within 2 years. Neither regimen was effective for long-term disease control in these children with neuroblastoma.

Streptozotocin (NSC-85998) in children with acute lymphocytic leukemia. A Southwest Oncology Group study.

Streptozotocin (NSC-85998), a nitrosourea antibiotic, was given to 18 children with acute lymphocytic leukemia in relapse in a dose of 500 mg/m2/day intravenously every day for five days. There were no responses in 14 fully evaluable patients. The principal toxicity consisted of gastrointestinal disturbances. Based on our findings and those of others in adults, steptozotocin appears to play no role in the management of acute lymphocytic leukemia.

Folinic acid rescue for vincristine toxicity.

Inadvertent vincristine sulfate overdosage was treated with folinic acid. The sequence of development of the signs and symptoms associated with known vincristine toxicity was accentuated; however, the duration of these toxicities was markedly compressed in time when compared with previous reports. The known pharmacologic and biologic activities of vincristine sulfate and presumed mechanism of counteractivity of folinic acid is presented.

Toxicity study of cytosine arabinoside and methotrexate in the maintenance therapy of childhood leukemia. A Southwest Oncology Group study.

In a toxicity study to determine the feasibility of treating patients with acute lymphocytic leukemia (ALL) using an intravenous combination of cytosine arabinoside (Ara-C) and methotrexate (MTX), the drugs were given either simultaneously or sequentially every two weeks. Twenty-nine patients were studied, 17 treated simultaneously, 12 treated sequentially. The tolerated doses of Ara-C and MTX were 60 mg/m2 and 90 mg/m2, respectively, for the simultaneous treatment schedule and 90 mg/m2 and 150 mg/m2, respectively, for the sequential treatment schedule. The dose-limiting factor of the drug combination was gastrointestinal toxicity. The observed recurrent vomiting on both schedules rendered the treatment unsuitable for maintenance therapy.

Combination chemotherapy with MOPP in children with recurrent brain tumors.

Twenty-three children with CNS tumors were treated with combination chemotherapy including nitrogen mustard, vincristine sulfate, procarbazine, and prednisone (MOPP). All but one had progressive or recurrent tumors following surgery and irradiation. In addition, nine of these patients had prior chemotherapy. Seventeen out of 23 patients (73.4%) responded to MOPP chemotherapy including seven patients who had prior chemotherapy with single or multiple agents such as VCR, nitrosoureas, intrathecal methotrexate, and VM-26. Three comatose patients who were being kept on Decadron without benefit recovered from coma. At the time of this report 8 of the 17 responders are surviving without evidence of recurrence 7--30 months from the start of MOPP chemotherapy. In two of these children chemotherapy has been completely stopped.

Hodgkin's disease and myelomonocytic leukemia: an ultrastructural and immunocytochemical study.

The ultrastructual and immunologic features of the initial Reed-Sternberg and Hodgkin cells are compared with the ultimate leukemic cell type in a child with Hodgkin's disease who subsequently developed acute myelomonocytic leukemia (AMML) following 29 months of chemotherapy. Hodgkin tumor cells contained cytoplasmic IgG and ultrastructurally resembled large immunoblasts, containing one or two round nuclei with large bizarre nucleoli, many polyribosomes, sparase endoplasmic reticulum, underdeveloped Golgi lamellae, and few cytoplasmic granules. The Hodgkin tumor cells displayed no evidence of phagocytosis. The leukemic monocytic cells did not contain cytoplasmic IgG and, ultrastrucally, exhibited and indented and irregular nuclear profile with less prominent nucleoli, numerous pleomorphic granules, a moderate number of free ribosomes, short segments of endoplasmic reticulum, and stacked Golgi lamellae. The cell surface was irregular and occasionally appeared involved in endocytic activity. These results indicate that the Hodgkin tumor cells originated from B lymphocytes rather than tissue macrophages, whereas the leukemic monocytes arose from the bone marrow-derived monocyte-macrophage series. The findings suggest further that AMML developing after Hodgkin's disease consitutes a second neoplasm rather than a leukemic transformation of Hodgkin tumor cells.

Study of cytosine arabinoside (NSC-63878) synchronization plus vincristine (NSC-67574), prednisone (NSC-10023), and L-asparaginase (NSC-109229) for remission induction in advanced acute leukemia in children.

Cytosine arabinoside (CA) was utilized in efforts to synchronize leukemic cells in DNA synthesis for treatment with vincristine, prednisone, and L-asparaginase in children with acute leukemia in relapse. The results did not indicate any therapeutic advantage for patients treated with this combination compared to those treated without any attempt at CA synchronization.