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The purpose of this article is to report on the development and initial use of a pesticide knowledge test (PKT) specifically designed to evaluate agricultural workers' knowledge of the content mandated by the federal Worker Protection Standard (WPS). The PKT is a 20-item, true-false test, used in a sample of 414 adult and adolescent migrant farmworkers in Oregon. The overall mean score, i.e., number correct, was 15.67(78.4%), with both adults and adolescents demonstrating the most difficulty with questions related to the overall health effects of pesticides. The internal consistency was 0.73, when estimated using a method to correct for small sample sizes. Only six items had less than 70% correct answers. Content validity was achieved by basing the items directly on the Worker Protection Standard; face validity was obtained by having the final version of the test reviewed by a bilingual (English-Spanish) educator familiar with the requirements of the WPS. Overall, adult participants scored better than adolescents, and those with previous pesticide training scored better than those without. There were no differences in scores based on gender or whether the test was taken in English or Spanish; however, participants who spoke indigenous languages scored significantly lower than those who did not. These results indicate that the PKT is a valid, reliable measure of worker knowledge of the content of the WPS, although it does not measure the extent to which that knowledge is actually used in the work setting.

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Several reports have demonstrated that radiofrequency catheter ablation provides effective control of a variety of supraventricular and ventricular tachycardias. This report details the results of radiofrequency catheter ablation in 1500 consecutive patients with a wide variety of supraventricular and ventricular tachycardias treated in the Instituto Nacional de Cardiología "Ignacio Chavez", between April 22, 1992 until December of 1999. Tachycardias were associated with the presence of an accessory pathway in 987 patients (65.8%). Dual accessory pathways were present in 24 patients giving a total of 1,012 accessory pathways. The mechanism of the arrhythmia was atrioventricular nodal reentrant tachycardia in 321 patients (21.4%). Ablation of the reentrant circuit of atrial flutter within the right atrium was attempted in 109 (7.2%) patients and a primary atrial tachycardia in 13 patients (0.8%). Atrioventricular node ablation and permanent pacemaker implantation were performed in 26 patients (1.7%). Finally we performed radiofrequency catheter ablation in 37 (2.4%) patients with ventricular tachycardia. Radiofrequency catheter ablation was successful in 908 of 1012 (89.7%) patients with accessory pathways with a complication rate of 10 (0.98%) and a recurrence rate of 92 (9%). AV nodal reentry was successfully abolished in 319 of 321 patients by selective ablation of the slow pathway in 297/321 (92.5%) patients and the fast pathway in 22/24 (92%) patients. The complication rate of this group was 8/321 (2.4%) with a recurrence rate of 34 patients (10.5%). The reentrant circuit of atrial flutter was ablated successfully in 86 of 109 (76.8%) patients with a recurrence flutter in 14 (12.8%) patients. Five of 13 (38.4%) cases of primary atrial tachycardia were successfully ablated. Complete AV block was achieved in 26 of 26 (100%) patients with atrial fibrillation or flutter treated by AV nodal ablation. The procedure was successful in 28 of 37 (75.6%) patients with fascicular ventricular tachycardia. The results of this series of patients demonstrates the safety and efficacy of radiofrequency ablation for the treatment of a wide variety of taquicardias with high rate of success 1375 of 1500 patients (91.6%), with 142 recurrences (9.4%), 15 complications (1%), and no mortality.

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Disponible en español

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Disponible en inglés

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To obtain information on the route(s) of ammonium assimilation in Streptomyces venezuelae, cell suspensions transferred to fresh medium lacking nitrogen were pulsed with [15N2]ammonium sulphate. Cells and extracellular fluids were examined by nuclear magnetic resonance and amino acid analysis to assess changes in amino acid pools and the disposition of [15N]ammonium. Following addition of [15N]ammonium, glutamate--glutamine pools of low cell density replacement cultures expanded rapidly and became progressively labelled with 15N, whereas the alanine pool size increased much more slowly and became labelled with 15N to a much lesser extent. These results are consistent with the assimilation of ammonium via glutamate dehydrogenase or glutamine synthetase--glutamate synthase rather than alanine dehydrogenase. Under anaerobic conditions, S. venezuelae assimilates ammonium into alanine rather than glutamate--glutamine. Alanine dehydrogenase may thus function as a vehicle to regenerate NAD+ to maintain substrate-level phosphorylation during periods of anaerobiosis.

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Cultures of Streptomyces venezuelae presented with a mixture of ammonium and an amino acid as nitrogen sources used both compounds together. Absence of ammonium repression of alternative nitrogen assimilation pathways was also observed when ammonium was added to cultures already growing on proline. The presence of ammonium in the medium ab initio depressed the yield of chloramphenicol. However, its addition to a culture growing on proline caused only a temporary inhibition of antibiotic synthesis, even when sufficient ammonium was added to create an excess. Continuous cultures supplied with ammonium as the growth-limiting nutrient showed no significant change in specific antibiotic production at different specific growth rates. The overall results indicate that in S. venezuelae neither nitrogen utilization pathways nor chloramphenicol biosynthesis is controlled by nitrogen repression.

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Bilateral hearing loss occurred in 9.7% of infants who survived despite very low birth weight (less than or equal to 1500 gm), 16.7% of infants who survived neonatal seizures, and 28.6% of infants who survived both low birth weight and neonatal seizures. All neonates received treatment in a single neonatal intensive care unit between 1976 and 1980. Twenty-two of 36 hearing-impaired children were normal physically and mentally, with IQ scores of greater than or equal to 85. Significant neonatal predictors of hearing loss in high-risk premature infants (less than or equal to 36 weeks gestation), as determined by multivariable testing, were prolonged respirator care, high serum bilirubin concentration, and hyponatremia. Exchange transfusions were associated with a decreased risk of hearing loss.

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Cultures of Streptomyces venezuelae released acidic metabolites during nitrogen-limited growth on glucose. The main products were pyruvic acid and alpha-ketoglutaric acid. Variation in the extent of acid production was observed; spores of the parental strain 13s gave approximately 10% of low-producing colonies when plated on acid-base indicator medium. Examination of one low producer, strain PC 51-5, showed that differences in acid production became apparent only in low-glucose media containing manganese. In both strains PC 51-5 and 13s, uptake of alpha-keto-[5-14C]glutaric acid occurred by diffusion and no marked differences in permeability to alpha-ketoglutarate were detected. However, differences were observed in the activity of alpha-ketoglutarate dehydrogenase. In cultures of strain PC 51-5, the specific activity of the enzyme increased throughout growth, whereas in the parental strain activity decreased and could not be detected in older mycelium. Loss of enzyme activity was accompanied by excretion of alpha-ketoglutaric acid and failure to assimilate the product after glucose exhaustion. The results suggest that accumulation of pyruvic and alpha-ketoglutaric acids in S. venezuelae cultures grown in glucose-containing media may be due to regulatory suppression of the dehydrogenases by this carbon source.

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Cultures of Streptomyces venezuelae grown in a medium containing glucose with mixtures of ammonium and nitrate as the nitrogen source produced chloramphenicol in a distinct idiophase that followed biomass accumulation. Analysis of fermentation broths showed that ammonium and nitrate were taken up consecutively by the organism. Measurements of nitrate reductase in the mycelium established that the enzyme was constitutive and that its specific activity did not increase during the period when ammonium was exhausted from the medium and nitrate was assimilated. The enzyme was neither repressed nor inhibited by ammonium. Production of chloramphenicol was also delayed until ammonium had been consumed and remained slow until subsequent depletion of nitrate. Arylamine synthetase, the initial enzyme in the pathway of antibiotic biosynthesis, showed no marked change in specific activity during utilization of the two nitrogen sources. The result suggests that the mechanism causing preferential utilization of ammonium does not simultaneously control the onset of chloramphenicol biosynthesis.

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The relationship between chloramphenicol production and nitrogen metabolism in Streptomyces venezuelae was examined in stirred jar cultures under pH control. Nitrogen sources that supported rapid biomass accumulation gave low rates of antibiotic synthesis during growth. This was consistent with a general incompatibility between fast growth and high yields of chloramphenicol. In media where the growth rate was reduced below the attainable maximum by the rate at which nitrogen could be assimilated, chloramphenicol production was associated with biomass accumulation. Enzymes that are potentially associated with nitrogen assimilation pathways were assayed in cultures supplied with nitrogen sources supporting markedly different growth rates. The results indicated that glutamine synthetase and alanine dehydrogenase levels were relatively insensitive to changes in growth rate and nitrogen source depletion. Glutamate dehydrogenase and glutamate synthase, on the other hand, showed high activity in cultures assimilating ammonium nitrogen and markedly decreased activity with poorer nitrogen sources or when ammonium was depleted. If chloramphenicol biosynthesis is coordinately controlled by mechanisms that regulate nitrogen assimilation, glutamate synthase and glutamate dehydrogenase are the most likely enzymes that manifest the regulatory linkage.

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This report is based on an analysis of the experience with all births in several urban and rural areas of the United States. All infants whose birth weight was in the lowest quartile for their week of gestation were designated as small for gestational age regardless of their birth weight or length of gestation; other infants were considered appropriate for gestation age. We interpret the data to indicate that appropriate-for-gestational age and small-for-gestational age infants, all of low birth weight, differ in the nature of their risk for adverse outcome as determined by an assessment at one year of age, although both are at approximately equal risk of adverse outcome overall. In each weight group, the total proportion of infants who either died before one year of age or were handicapped at one year of age was similar for small-for-gestational age and appropriate-for-gestational age infants, but appropriate-for-gestational age infants were at greater risk of neonatal death and small-for-gestational age infants were at greater risk of problems manifested during the first year of life or at one year of age. As the findings are based on data obtained from entire populations (rather than from infants born in particular hospitals), they are likely to be generalizable.

PIP: Data on all births and infant deaths in the US were derived from reproduced computer tapes provided by local and state vital statistics units to analyze the risk factor involving intrauterine growth retardation (IUGR) as manifested by low birth weight for gestational age. The findings address the mortality of these infants and their morbidity as determined by an assessment at 1 year of age compared with infants who were comparably small but of appropriate weight for gestational age. In each region, matching of birth and death certificates provided data to assess neonatal and postneonatal mortality rates in 1974 and 1975 by birth weight; in 6 of the 8 areas gestational age based on the date of the last menstrual period was also available. Morbidity data for infants surviving to 1 year of age were obtained through a household survey of a random sample of infants born in the 8 regions during a 6-month period in 1976 and identified through birth certificates. The samples were selected to include all of the infants weighing 2500 gm or less at birth and, on average, 3% of those weighing more than 2500 gm at birth for all regions combined. The survey instrument consisted of 2 parts: an interview with the mother to obtain sociodemographic data and information on the child's illnesses, hospitalizations, malformations, participation in special followup programs, usual source of care, and health care received; and observations on the child. The number of infants visited totaled 4989, including 3179 infants with birth weights of 2500 gm or less, 1777 infants weighing over 2500 gm at birth, and 33 infants of unknown birth weight. Low birth weight for gestational age (SGA) was defined statistically as the lowest 25th percentile of weight at each week of gestation. Over 2/3 of infants in each birth weight group under 3000 gm were categorized as SGA, even though SGA was defined as the lowest 25th percentile of infants at each week of gestation. The SGA infants were more likely to survive to 1 year of age, largely because of greater survival in the neonatal period, in all weight categories under 2501 gm. SGA survivors under 2001 gm were more likely than appropriate weight for gestational age (AGA) survivals to have severe, moderate, or mild impairment at 1 year, particularly at birth weights less than 1500 gm. Very small (1500 gm or less) SGA and AGA infants who survived and who did not have severe, moderate, or mild impairment appeared to be at approximately equal risk of rehospitalization and prolonged illnesses; SGA and AGA infants at birth weights above 2501 gm appeared to be at equal risk of problems manifest at 1 year of age. Table 1 provides data on only those rehospitalized children who did not have congenital defects or developmental delay. There were no consistent differences between AGA and SGA infants in the duration of original hospitalization, likelihood of rehospitalization, or total days of hospitalization in the 1st year of life.

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We report the association of oculocutaneous albinism and defective platelet function, the Hermansky-Pudlak syndrome, in two young Puerto Rican patients, a 17-year-old boy and a 9-year-old girl. Wide variation in pigmentation may obscure the diagnosis of albinism. Puerto Rican albinos are at increased risk of inheriting this autosomal recessive syndrome. Although usually mild, bleeding in affected patients can be life-threatening, especially after aspirin administration. Albino patients should be questioned about a history of bleeding and referred for hematologic consultation.

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A randomized double-blind study was carried out comparing single daily dose phenobarbital plus antipyretic instruction to a placebo plus antipyretic instruction to prevent a recurrent seizure following an initial simple febrile seizure. Parents of 138 consecutive children presenting to an emergency room with a first simple febrile convulsion received verbal and written instructions about fever control. Seventy-nine then agreed to participate in this study. Children were randomized to receive either placebo with riboflavin tracer (n = 40) or phenobarbital 5 mg/kg in a single daily dose with a riboflavin tracer (n = 39) for 12 months or until another seizure occurred. Urine fluorescence for riboflavin was used to monitor compliance in all patients. Serum phenobarbital levels were obtained at each follow-up visit and averaged 1.4 mg/dl throughout the study. The significant difference (P less than 0.02) in the incidence of recurrent seizures between patients receiving phenobarbital (2/39) and those receiving placebo (10/40) suggests that a single daily dose of phenobarbital is more effective than counseling parents about antipyretic therapy in preventing recurrent seizures following an initial febrile seizure.

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Cognitive and behavioral effects of phenobarbital in toddlers were assessed in a randomized, placebo-controlled study of patients who had had a febrile seizure. There were no significant differences in IQ (Binet or Bayley Scales) between placebo and phenobarbital groups after eight to 12 months of therapy. However, detrimental effects of phenobarbital were found in memory, for which serum level influenced scores, and in comprehension, in that length of treatment time affected performance. Hyperactivity was not seen. Behavioral changes, reported by parents, were increased fussiness and a characteristic disturbance of sleep. These changes varied in severity and were classified as transient, dose related, or unacceptable. After 12 months in the study, most parents could not distinguish between phenobarbital and placebo. Our data suggest that although most toddlers do not have major side effects from phenobarbital therapy when treated for a year, serum levels and length of time on phenobarbital should be kept at a minimum to reduce negative cognitive and behavioral effects.

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Infant mortality rates (IMR) have traditionally been considered useful as health status indicators, and changes in these rates are thought to reflect changes in both medical care services and socio-economic circumstances. In order to explore this relationship of IMR with medical core and socio-economic factors in a developing country, Chilean health zone data for the decade 1960--1970 were used to construct 25 variables which were then classified into groups representing antenatal-obstetric services, acute and preventive medical services and socio-economic variables. In an analysis which involved developing a series of linear multiple regression equations for each year of the decade 1960--1970 with IMR as the dependent variable, the percentage of births with professional attention proved to be the stronger variable.

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