Host Selection, Growth, and Survival of Melonworm (Lepidoptera: Crambidae) on Four Cucurbit Crops Under Laboratory Conditions.

The melonworm, Diaphania hyalinata L. (Lepidoptera: Crambidae), is one of the most serious insect problems affecting cucurbit production. We evaluated the relative preference and suitability of yellow squash, zucchini, cucumber, and watermelon to melonworm by measuring its oviposition, larval feeding preference, survivorship, and developmental responses in the laboratory. Whole plants were used for oviposition study, whereas host leaf discs were used for all the other studies. Watermelon feeding resulted in the longest larval development period (14.3 d), greatest prepupal weights and survivals rates (92%; first instar to adult) among the four crops. However, for watermelon, adult oviposition preference (199.5 eggs/♀), egg survival (70%), and larval feeding (4.1% defoliation) were numerically or statistically lowest, and larval head capsule widths and whole-body lengths were smallest. When differences occurred among these variables, yellow squash, zucchini, and cucumber were each typically higher (or quicker to develop) than watermelon. So why do melonworm adults not prefer watermelon, or at least select it as frequently as squash and cucumber when ovipositing? The answer likely is that there might be some variation in the important chemical components among these cucurbits. We suggest that comparison of kairomones and allomones from watermelon and related cucurbits would be very useful for determining the combination resulting in the lowest risk of damage to the more susceptible cucurbits (assuming the levels can be modified without seriously affecting the crops).

Distribution of Zelus longipes (Hemiptera: Reduviidae) in south Florida corn fields and its functional response to corn-infesting picture-winged flies (Diptera: Ulidiidae).

The milkweed assassin bug, Zelus longipes (L.) (Hemiptera: Reduviidae), is a generalist predator and a potential biological control agent of picture-winged flies (Diptera: Ulidiidae), which cause considerable economic damage to sweet corn yields in Florida. We studied the potential of Z. longipes as a biocontrol agent of four ulidiid pests in corn fields: Euxesta stigmatias Loew, Euxesta eluta Loew, Euxesta annonae F., and Chaetopsis massyla Walker. Within-plant and within-field distributions of Z. longipes and ulidiids and functional responses of Z. longipes to ulidiid prey were determined. Highest numbers of Z. longipes and ulidiids in the R1, R2, and R3 corn stages were generally in the basal or middle leaves at 09:00 h EST, ears at 13:00 h EST, and top and tassel at 17:00 h EST. Hence, there seemed to be a coordinated migration of Z. longipes and ulidiids from the lowest to the highest parts of the corn plant during the day. Within the corn field, aggregated (clumped) distributions were most common for Z. longipes and ulidiids especially in the later R2 and R3 stages based on Taylor's power law, Iwao's patchiness regression, index of dispersion, and Lloyd's patchiness indices of dispersion. However, predator and prey populations were lower in the R1 stage, and there were inconsistent results for dispersion indices among times of day and between predators and prey. Ulidiid distributions in R1 were mostly regular (uniform) at 13:00 h EST, but aggregated at 09:00 h and 17:00 h. However, Z. longipes R1 distributions were mostly aggregated at 13:00 h, but random or regular at 09:00 h and 17:00 h EST. Handling times for male and female Z. longipes were 1.0-1.39 h and 0.67-0.97 h, respectively, and each had a type II functional response to E. stigmatias, E. eluta, and E. annonae and consumed about five flies per day. Although the population abundance of Z. longipes can vary between seasons, it appears to be a promising biocontrol agent of ulidiid flies in corn.

[Fatal Sweet syndrome associated to chronic idiopathic systemic inflammatory response syndrome]. / Síndrome de Sweet de evolución fatal asociado a síndrome de respuesta inflamatoria sistémica crónico idiopático.

Sweet syndrome is one of the cutaneous processes more frequently associated to systemic diseases. Its association to the systemic inflammatory response syndrome has rarely been described. We report a case of chronic and relapsing Sweet syndrome associated to a chronic and idiopathic systemic inflammatory response syndrome that lasted seven years and proved fatal to the patient. Among the rare cases of Sweet syndrome associated to a systemic inflammatory response syndrome that have been described there have not been any fatal cases as occurred with our patient.

Characteristics of cardiac arrest in cancer patients as a predictor of survival after cardiopulmonary resuscitation.

BACKGROUND: Despite advances in cardiopulmonary resuscitation and the education of its providers, survival remains dismal for cancer patients suffering in-hospital cardiac arrest. In an effort to determine if characteristics of cardiac arrest would represent a useful parameter for prognostication and recommendations regarding the suitability of ongoing resuscitation for various groups, this review was undertaken for patients who experienced in-hospital cardiac arrest. METHODS: A retrospective study of data gathered between January 1993 and December 1997 was undertaken in a 518-bed comprehensive cancer center. The records of 243 inpatients who experienced cardiac arrest and received cardiopulmonary resuscitation were reviewed, and their course observed until hospital discharge or death. RESULTS: Sixteen of 73 patients (22%) who had sudden, unanticipated cardiac arrests survived to be discharged from the hospital; however, none (0 of 171) of the patients who experienced an anticipated cardiac arrest survived (P < 0.001). Logistic regression analysis revealed that anticipated cardiac arrest associated with metabolic derangement was an independent predictor of hospital mortality. CONCLUSIONS: Patients experiencing an anticipated cardiac arrest, the course of which could not be interrupted through aggressive management in an intensive care unit, have an extremely poor prognosis. Ongoing resuscitative measures in these patients need not be routinely provided. The authors suggest an algorithm for resuscitation that evaluates the characteristics of the arrest as a prognostic factor. This algorithm should be implemented once progressive deterioration spirals toward cardiac arrest that cannot be prevented. Such an approach should avoid painful and costly interventions that are futile with the present techniques of cardiopulmonary resuscitation.

1,4-pentadienyl-3-sulfonamides: frameworks for "disfavored" radical cascade cyclizations.

[reaction: see text]. 1,4-pentadienyl-3-sulfonamides afford products including those resulting from disfavored 5-endo-trig reactions when subjected to radical cyclization conditions. Products resulting from pathways featuring 4-exo-trig cyclizations are also detected, even when the 4-exo-trig reaction leads to a highly strained bicyclo[3.2.0] ring system.

Incidence, cost, and outcomes of bleeding and chemotherapy dose modification among solid tumor patients with chemotherapy-induced thrombocytopenia.

PURPOSE: To describe the incidence and outcomes of bleeding and chemotherapy dose modifications associated with chemotherapy-induced thrombocytopenia (platelets < 50,000/microL). PATIENTS AND METHODS: Six hundred nine patients with solid tumors or lymphoma were followed-up during 1,262 chemotherapy cycles complicated by thrombocytopenia for development of bleeding, delay or dose reduction of the subsequent cycle, survival, and resource utilization. The association between survival and bleeding or dose modification was examined using the Cox proportional hazards model. Predisposing factors were identified by logistic regression. RESULTS: Bleeding occurred during 9% of cycles among patients with previous bleeding episodes (P <.0001), baseline platelets less than 75,000/microL (P <.0001), bone marrow metastases (P =.001), poor performance status (P =.03), and cisplatin, carboplatin, carmustine or lomustine administration (P =.0002). Major bleeding episodes resulted in shorter survival and higher resource utilization (P <.0001). Chemotherapy delays occurred during 6% of cycles among patients with more than five previous cycles (P =.003), radiotherapy (P =.03), and disseminated disease (P =.04). They experienced similar clinical outcomes but used significantly more resources. Dose reductions occurred during 15% of cycles but were not associated with poor clinical outcomes or excess resource utilization. Significantly shorter survival and higher resource utilization were observed among the 20% of patients who failed to achieve an adequate response to platelet transfusion. CONCLUSION: The incidence of bleeding is low among solid tumor patients overall but exceeds 20% in some subgroups. These subgroups are easily identifiable using routinely available clinical information. A clinical prediction rule is being developed. Poor response to platelet transfusion is a clinically and financially significant downstream effect of thrombocytopenia and warrants further investigation.

Influence of an advance directive on the initiation of life support technology in critically ill cancer patients.

OBJECTIVE: To determine whether the presence of an advance directive at admission to an intensive care unit (ICU) influenced the decision to initiate life support therapy in critically ill cancer patients. DESIGN: Matched-pairs case-control design. SETTING: The University of Texas M. D. Anderson Cancer Center ICU. PATIENTS: Of 872 patients treated in the ICU from 1994 to 1996, 236 (27%) were identified as having advance directives. One hundred thirty five patients who had advance directives were successfully matched to 135 patients who did not on the basis of type of malignancy, reason for admission to ICU, severity of illness, and age. These pairs comprised the study group. INTERVENTIONS: Life-supporting interventions were compared between the matched groups using the McNemar and Wilcoxon matched-pairs signed ranks tests. MEASUREMENTS AND MAIN RESULTS: No significant difference was found in the frequency with which the following interventions were applied in patients with and without advance directives (respectively): mechanical ventilation, 44% vs. 42%; inotropic support, 31% vs. 31%; pulmonary artery catheterization, 11% vs. 12%; cardiopulmonary resuscitation, 7% vs. 12%; and renal dialysis, 3% vs. 7%. There were also no differences in ICU (75% vs. 73%, respectively) or hospital (56% vs. 59%, respectively) survival. More patients with advance directives than those without had do-not-resuscitate orders within the first 72 hrs (19% vs. 11%, p =.046) and patients with advance directives had shorter ICU durations and lower ICU charges than patients without advance directives. CONCLUSIONS: After controlling for type of malignancy, reason for admission to the ICU, severity of illness, and age, the decision to initiate life-supporting interventions did not differ significantly among patients with and without advance directives. The presence of an advance directive, however, may have helped guide decisions earlier regarding duration of therapy and resuscitation status.

Identifying risk factors for imminent death in cancer patients with acute dyspnea.

A substantial proportion of cancer patients presenting to an emergency center (EC) or clinic with acute dyspnea survives fewer than 2 weeks. If these patients could be identified at the time of admission, physicians and patients would have additional information on which to base decisions to continue therapy to extend life or to refocus treatment efforts on palliation and/or hospice care alone. The purpose of this study was to identify risk factors for imminent death (survival

Time to clinical response: an outcome of antibiotic therapy of febrile neutropenia with implications for quality and cost of care.

PURPOSE: To determine whether antibiotic regimens with similar rates of response differ significantly in the speed of response and to estimate the impact of this difference on the cost of febrile neutropenia. METHODS: The time point of clinical response was defined by comparing the sensitivity, specificity, and predictive values of alternative objective and subjective definitions. Data from 488 episodes of febrile neutropenia, treated with either of two commonly used antibiotics (coded A or B) during six clinical trials, were pooled to compare the median time to clinical response, days of antibiotic therapy and hospitalization, and estimated costs. RESULTS: Response rates were similar; however, the median time to clinical response was significantly shorter with A-based regimens (5 days) compared with B-based regimens (7 days; P =.003). After 72 hours of therapy, 33% of patients who received A but only 18% of those who received B had responded (P =.01). These differences resulted in fewer days of antibiotic therapy and hospitalization with A-based regimens (7 and 9 days) compared with B-based regimens (9 and 12 days, respectively; P <.04) and in significantly lower estimated median costs ($8,491 v $11,133 per episode; P =.03). Early discharge at the time of clinical response should reduce the median cost from $10,752 to $8,162 (P <.001). CONCLUSION: Despite virtually identical rates of response, time to clinical response and estimated cost of care varied significantly among regimens. An early discharge strategy based on our definition of the time point of clinical response may further reduce the cost of treating non-low-risk patients with febrile neutropenia.

Advance directives in critically ill cancer patients.

Although advance directives have been used since the 1970s, the discussion of these documents has become more common since the enactment of the Patient Self-Determination Act in 1991. This study evaluated the frequency of advance directives in critically ill patients at a tertiary cancer center and found that cancer patients had a relatively low completion rate of advance directives (27%). The finding that advance directives were more common among Caucasians than other ethnic groups signifies the importance of considering cultural differences when addressing end-of-life issues with patients. The documents also were found more often in older patients with serious diseases. The relationship between hospital mortality and advance directives is complex. The most seriously ill patients and patients with leukemia had the highest mortality and the highest rate of advance directives. Further research on the interactions among mortality, advance directives, and severity of illness is needed. This research contributes to the body of knowledge available on advance directives and particularly sheds light on advance directives in critical ill cancer patients.

Influence of data display formats on physician investigators' decisions to stop clinical trials: prospective trial with repeated measures.

OBJECTIVE: To examine the effect of the method of data display on physician investigators' decisions to stop hypothetical clinical trials for an unplanned statistical analysis. DESIGN: Prospective, mixed model design with variables between subjects and within subjects (repeated measures). SETTING: Comprehensive cancer centre. PARTICIPANTS: 34 physicians, stratified by academic rank, who were conducting clinical trials. INTERVENTIONS: PARTICIPANTS were shown tables, pie charts, bar graphs, and icon displays containing hypothetical data from a clinical trial and were asked to decide whether to continue the trial or stop for an unplanned statistical analysis. MAIN OUTCOME MEASURE: Percentage of accurate decisions with each type of display. RESULTS: Accuracy of decisions was affected by the type of data display and positive or negative framing of the data. More correct decisions were made with icon displays than with tables, pie charts, and bar graphs (82% v 68%, 56%, and 43%, respectively; P=0.03) and when data were negatively framed rather than positively framed in tables (93% v 47%; P=0.004). CONCLUSIONS: Clinical investigators' decisions can be affected by factors unrelated to the actual data. In the design of clinical trials information systems, careful consideration should be given to the method by which data are framed and displayed in order to reduce the impact of these extraneous factors.

Transcription of INO2 and INO4 is regulated by the state of protein N-myristoylation in Saccharomyces cerevisiae.

Inositol regulates transcription of Saccharomyces cerevisiae genes required for de novo synthesis of acylCoAs and phospholipids. Removal of inositol results in transcriptional activation by heterodimeric complexes of two bHLH proteins, Ino2p and Ino4p. In the presence of inositol, transcription is repressed by Opi1p. MyristoylCoA:protein N-myristoyltransferase (Nmt1p) is an essential enzyme whose activity is influenced by cellular myristoylCoA pool size and availability. nmt451Dp contains a Gly451-->Asp substitution that produces temperature-dependent reductions in affinity for myristoylCoA and associated reductions in acylation of cellular N-myristoylproteins. The conditional lethality produced by nmt1-451D is rescued at temperatures up to 33 degreesC by withdrawal of inositol. We tested the hypothesis that N-myristoylproteins function to regulate INO2, INO4 and/or OPI1 transcription, thereby affecting the expression of inositol-sensitive genes that influence myristoylCoA metabolism. The effect of nmt1-451D on INO2 , INO4 and OPI1 promoter activities was examined by introducing episomes, containing their 5' non-transcribed domains linked to reporters, into isogenic NMT1 and nmt1-451D cells. The activity of INO2 is significantly higher, INO4 significantly lower and OPI1 unaffected in nmt1-451D cells, both in the presence and absence of inositol. These changes are associated with a net increase in expression of some inositol target genes, including FAS1 . FAS1 encodes one of the subunits of the fatty acid synthase complex that catalyzes de novo acylCoA (including myristoylCoA) biosynthesis. Augmented expression of FAS1 overcomes the kinetic defects in nmt451Dp. FAS1 expression is Ino2p-dependent in NMT1 cells at 24-33 degreesC. In contrast, FAS1 expression becomes Ino2p-independent in nmt1-451D cells at temperatures where efficient acylation of cellular N-myristoylproteins is jeopardized. The ability to maintain expression of FAS1 in nmt1-451Dino2 Delta cells suggests the existence of another transcription factor, or factors, whose expression/activity is inversely related to overall levels of cellular protein N-myristoy-lation. This factor is not functionally identical to Ino2p since other inositol-responsive genes (e.g. CHO1 ) maintain INO2 -dependent expression in nmt1-451D cells.

Mississippi mud in the 1990s: risks and outcomes of vancomycin-associated toxicity in general oncology practice.

BACKGROUND: Discrepancies between the severity of toxicities reported in early clinical trials and recent clinical experience with vancomycin have led to confusion regarding the need for routine serum vancomycin level monitoring and discontinuation of vancomycin when toxicities occur. Therefore, the authors examined the incidence, outcomes, and predictive factors of vancomycin-associated toxicities in general oncology practice with the goal of developing clinically relevant prediction rules and guidelines. METHODS: All 742 consecutive cancer patients who received vancomycin at a comprehensive cancer center during a 3-month period were followed prospectively for the development and outcome of phlebitis, rash, ototoxicity, and nephrotoxicity. Logistic regression was used to derive a multiple variable model of the risk of nephrotoxicity. A clinical prediction rule, the Nephrotoxicity Risk Score, was developed from the risk model and validated prospectively. RESULTS: Phlebitis occurred in 3% of patients (95% confidence interval [95% CI], 2-4%), predominantly those with recently inserted central venous catheters. Rashes occurred in 11% of patients (95% CI, 9-13%); however, all but 4 patients also were receiving beta-lactam antibiotics. Clinical evidence of ototoxicity developed in 6% of patients (95% CI, 4-9%) who were receiving vancomycin plus other ototoxic agents and only 3% of patients (95% CI, 2-5%) not receiving other ototoxic agents (P = 0.08). Nephrotoxicity occurred in 17% of patients (95% CI, 15-20%). Logistic regression revealed that factors associated with an increased risk of nephrotoxicity included administration of other mild to moderate (P = 0.01) or severely nephrotoxic agents (P < 0.001) or an acute physiology and chronic health evaluation (APACHE) score > 40 (P = 0.002). Elevated serum vancomycin peak levels did not reliably predict subsequent nephrotoxicity. CONCLUSIONS: Vancomycin-associated toxicities usually are mild and self-limiting. Some patients are at a significantly higher risk of nephrotoxicity but the authors believe these individuals can be identified reliably with the Nephrotoxicity Risk Index using information available at vancomycin initiation. Further testing of the Nephrotoxicity Risk Index is ongoing.

Medical futility and appropriate medical care in patients whose death is thought to be imminent.

Often it is very difficult to make decisions involving the termination of aggressive cancer care in the case of patients who are no longer benefiting. Among these patients, our ability to "do everything possible" to continue life is in conflict with "doing the right thing"; the greatest benefit to these patients derives from delivering excellent supportive care and assisting them in understanding and accepting end-of-life issues. Furthermore, in a cost-conscious environment with limited resources, all patients and, indeed, all of society, benefit when aggressive and often costly cancer care is limited to those patients who are likely to benefit. However, these issues are complex, blending treatment science and ethics, and thus, the physician frequently has no objective reference point on which to base the decisions. This paper integrates the principles of ethics (respect for autonomy, beneficence, nonmaleficence, and justice) and three difficult issues encountered by physicians in clinical decision-making in terminal cancer patients in the American healthcare system. These issues include: medical futility and appropriate care, applications of outcomes research in clinical decision-making, and impact of cost, particularly in a managed care environment, on treatment choice. These topics are illustrated with reference to patients presenting to our emergency center with stage IV lung cancer and dyspnea, and the application of an outcomes model under development to predict imminent death in these patients is discussed. Outcomes models may provide patients, their families, and their physicians with objective data on which to base end-of-life decision-making. Minimizing aggressive treatment of terminally ill patients may provide better life quality and will reduce costs during the patients' end of life. Ethics plays a crucial role in integrating medical science, patient choice, and cost in making appropriate decisions.

Dyspnea in cancer patients. Etiology, resource utilization, and survival-implications in a managed care world.

BACKGROUND: Dyspnea is the fourth most common symptom of patients who present to the emergency department (ED) at The University of Texas M. D. Anderson Cancer Center and may, in some patients with advanced cancer, represent a clinical marker for the terminal phase of their disease. This retrospective study describes the clinical characteristics of these patients, the resource utilization associated with the management of dyspnea, and the survival of patients with this symptom. METHODS: The authors randomly selected 122 of 1068 patients presenting with dyspnea for a retrospective analysis. The median age of the patients was 58 years (range, 23-90 years) and 53% were female. Underlying malignancies were breast cancer (30%), lung cancer (37%), and other cancers (34%). Approximately 94% of the patients had received prior cancer treatment and the majority (69%) had uncontrolled, progressive disease. RESULTS: The most common treatments administered in the ED were oxygen (31%), beta-2 agonists (14%), antibiotics (12%), and narcotics (11%). Approximately 60% of patients were admitted to the hospital from the ED for further treatment of dyspnea and the underlying malignancy, and the median length of stay was 9 days. The median overall survival after the ED visit for dyspnea was 12 weeks. Specific diagnoses were associated with different median survival rates: lung cancer patients: 4 weeks; breast cancer patients: 22 weeks (P = 0.0073, vs. lung cancer); and other cancer diagnoses: 27 weeks (P = 0.0027, vs. lung cancer). CONCLUSIONS: Lung cancer patients presenting to the ED with dyspnea have much shorter survival than patients with other malignancies. For some patients, the presence of dyspnea requiring emergency treatment may indicate a phase in their illness in which resources should be shifted from acute intervention with hospitalization to palliative and supportive care measures.

Teaching cancer pain management: durability of educational effects of a role model program.

BACKGROUND: Inadequate management of cancer related pain has resulted primarily from attitudinal barriers and a lack of knowledge about clinical assessment, the administration of analgesics, and therapeutic interventions. METHODS: Fifty health-care providers (13 physicians, 21 nurses, and 16 pharmacists), working as a team, participated in a Role Model Program that presented principles of cancer pain management. A questionnaire that evaluated the fund of knowledge and attitudes regarding cancer pain management was administered prior to the 1-day workshop, at the end of the workshop, and at 4 and 12 months follow-up. The workshop consisted of lectures and discussion groups; in the discussion groups, concepts were clarified, cases presented, and barriers to optimal cancer pain management identified. RESULTS: Significant improvements in attitudes (P < 0.01), knowledge (P < 0.01), and total scores (P < 0.002) were observed when the preworkshop responses were compared with those obtained immediately after instruction. Scores on the questionnaire were the same or slightly better at both 4 and 12 months in follow-up, demonstrating no loss in acquired knowledge or attitude. Comparison of the postworkshop scores with those at 12 months follow-up were significantly better in attitude (P < 0.03), and in total score (P < 0.01); improvements in knowledge also approached significance (p < 0.06). These represented continuing improvements because significant differences in the attitude scores (P < 0.05) and the total score (P < 0.05) were observed when the 4-month and 12-month follow-up responses were evaluated. The effectiveness of the program in the transference of knowledge was also measured; in the first year of the program, more than 4500 health-care professionals were subsequently informed about cancer pain management from the Role Model Participants. CONCLUSIONS: Significant improvements were observed immediately in both attitude and knowledge of cancer pain management principles after the 1-day Role Model Workshop. These improvements continued, as determined at 4 and 12 months follow-up. The Role Model Participants were highly motivated to share the learned principles of cancer pain management with other health-care professionals. These results are consistent with other Role Model Programs that both instruct and involve the participants. The Role Model Program is an efficient and effective means of educating health-care professionals in the concepts of cancer pain management.

Phenobarbital and cerebral blood flow during hypotension in newborn pigs.

Phenobarbital sodium (PhS) has been used in anticonvulsant concentrations in premature newborns in attempts to prevent peri- and intraventricular hemorrhages (PIVH). Its effectiveness in preventing PIVH in clinical situations is still uncertain; however, PhS has reduced PIVH after hypertension in newborn beagles, and it has lowered cerebral blood flow (CBF) during hypertension in newborn beagles and piglets. We hypothesized that PhS might reduce CBF during systemic hypotension. Twelve control and 12 PhS-treated piglets (1 to 2 d old) were used for microsphere determinations of CBF during 1) steady state; 2) 30 min after PhS (treatment group) or saline infusion (controls); and 3 and 4) during two levels of graded hypotension. Mean arterial blood pressure (MABP) was 61 +/- 13 (SD) mm Hg (controls) and 57 +/- 13 (SD) mm Hg (PhS) during steady state. Thirty min after the PhS or saline infusion, MABP and CBF remained unchanged in both groups. CBF during hypotension at MABP of 41 +/- 5 (SD) mm Hg was significantly higher in controls than was CBF at MABP of 39 +/- 6 (SD) mm Hg in the PhS-treated group (p = 0.044); CBF in the two groups during the second hypotensive phase was not significantly different. However, LOWESS regression suggested that the CBF from the controls dropped as the arterial pressure decreased to less than 37 mm Hg, whereas PhS treatment lowered CBF during hemorrhagic hypotension compared with controls at blood pressures greater than 37 mm Hg but did not lower CBF further at lower systemic blood pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of sinefungin and synthetic analogues on RNA and DNA methyltransferases from Streptomyces.

Sinefungin is an antibiotic structurally related to S-adenosylmethionine. It has been described as an inhibitor of RNA transmethylation reactions in viruses and eukaryotic organisms, but not in bacteria. We show here that sinefungin strongly inhibits RNA methyltransferase activity, but not the biosynthesis of these enzymes in Streptomyces. All the methylated bases found in Streptomyces RNA (1-methyladenine, N6-methyladenine, N6,N6-dimethyladenine and 7-methylguanine) are inhibited by this antibiotic. Experiments with sinefungin analogues show that specific changes in the ornithine radical of the molecule still preserve its inhibitory capability. The substitution of the adenine radical by uridine causes the loss of the inhibitory effect. These results and our former studies on Streptomyces DNA methylation, suggest that nucleic acid modification is the main target of sinefungin in Streptomyces.