RESUMEN
BACKGROUND: Acute graft pyelonephritis (AGPN) is thought to affect graft and patient survival among renal transplant recipients. The objective was to compare outcomes among early AGPN (< 6â¯months from transplant) versus late AGPN (> 6â¯months from transplant). METHODS: This retrospective study analyzed 150 patients with AGPN dividing them into early and late AGPN from 2008 to 2016. Predictors of graft loss and mortality were compared using logistic regression analysis. Graft survival and patient survival were analyzed using Kaplan-Meyer survival plots. RESULTS: 55.3% (nâ¯=â¯83) had early AGPN and 44.7% (nâ¯=â¯67) had late AGPN. In early AGPN group, 13.3% had CMV disease on follow up compared to 3% in late AGPN group (pâ¯<â¯0.05). 26.5% had history of prolonged Foley's catheterization (> 5â¯days), 38.6% had prolonged DJ stent in-situ (> 2â¯weeks) following transplant surgery in the early AGPN compared to 7.5% and 19.4% respectively in the late AGPN group (pâ¯<â¯0.05). Recurrent GPN was more common in the late AGPN group - (35.8% versus 18.1%). Presence of renal abscess was predictive of graft loss in Univariate analysis (HR-6.12, pâ¯<â¯0.004). There was decreased death censored graft survival in the early AGPN group (p-0.035) with no significant difference in patient survival among the two groups. CONCLUSION: Occurrence of early AGPN had a significant impact on long term graft survival in renal transplant recipients with no significant effect on patient survival. This study underlines the paramount importance of the prevention of UTIs in renal transplant recipients.
Asunto(s)
Trasplante de Riñón , Pielonefritis , Infecciones Urinarias , Humanos , Estudios Retrospectivos , Rechazo de Injerto/prevención & control , Pielonefritis/epidemiología , Supervivencia de Injerto , Infecciones Urinarias/epidemiología , Factores de Riesgo , Resultado del TratamientoRESUMEN
BACKGROUND: After a gradual decline from 1990 to 2004, the percentage of births occurring at home increased from 2004 to 2008 in the United States. The objective of this report was to examine the recent increase in home births and the factors associated with this increase from 2004 to 2008. METHODS: United States birth certificate data on home births were analyzed by maternal demographic and medical characteristics. RESULTS: In 2008, there were 28,357 home births in the United States. From 2004 to 2008, the percentage of births occurring at home increased by 20 percent from 0.56 percent to 0.67 percent of United States births. This rise was largely driven by a 28 percent increase in the percentage of home births for non-Hispanic white women, for whom more than 1 percent of births occur at home. At the same time, the risk profile for home births has been lowered, with substantial drops in the percentage of home births of infants who are born preterm or at low birthweight, and declines in the percentage of home births that occur to teen and unmarried mothers. Twenty-seven states had statistically significant increases in the percentage of home births from 2004 to 2008; only four states had declines. CONCLUSION: The 20 percent increase in United States home births from 2004 to 2008 is a notable development that will be of interest to practitioners and policymakers. (BIRTH 38:3 September 2011).
Asunto(s)
Parto Domiciliario/tendencias , Adulto , Certificado de Nacimiento , Etnicidad/estadística & datos numéricos , Femenino , Humanos , Embarazo , Resultado del Embarazo , Riesgo , Estados UnidosRESUMEN
In 2005, the United States ranked 30th in the world in infant mortality. Infant mortality rates for preterm (<37 weeks of gestation) infants are lower in the United States than in most European countries; however, infant mortality rates for infants born at 37 or more weeks of gestation are higher in the United States than in most European countries. One in 8 births in the United States were preterm in 2005, compared with 1 in 18 births in Ireland and Finland, and 1 in 16 in France and Sweden. If the United States had Sweden's distribution of births by gestational age, nearly 8,000 infant deaths in the United States would be averted each year, and the U.S. infant mortality rate would be one-third lower. The main cause of the United States' high infant mortality rate when compared with Europe is the very high percentage of preterm births in the United States, the period when infant mortality is greatest.
Asunto(s)
Mortalidad Infantil , Recolección de Datos/métodos , Europa (Continente)/epidemiología , Edad Gestacional , Humanos , Recien Nacido con Peso al Nacer Extremadamente Bajo , Recién Nacido , Recien Nacido Prematuro , Estados Unidos/epidemiologíaRESUMEN
BACKGROUND AND PURPOSE: Spiral MR imaging has several advantages compared with Cartesian MR imaging that can be leveraged for added clinical value. A multicenter multireader study was designed to compare spiral with standard-of-care Cartesian postcontrast structural brain MR imaging on the basis of relative performance in 10 metrics of image quality, artifact prevalence, and diagnostic benefit. MATERIALS AND METHODS: Seven clinical sites acquired 88 total subjects. For each subject, sites acquired 2 postcontrast MR imaging scans: a spiral 2D T1 spin-echo, and 1 of 4 routine Cartesian 2D T1 spin-echo/TSE scans (fully sampled spin-echo at 3T, 1.5T, partial Fourier, TSE). The spiral acquisition matched the Cartesian scan for scan time, geometry, and contrast. Nine neuroradiologists independently reviewed each subject, with the matching pair of spiral and Cartesian scans compared side-by-side, and scored on 10 image-quality metrics (5-point Likert scale) focused on intracranial assessment. The Wilcoxon signed rank test evaluated relative performance of spiral versus Cartesian, while the Kruskal-Wallis test assessed interprotocol differences. RESULTS: Spiral was superior to Cartesian in 7 of 10 metrics (flow artifact mitigation, SNR, GM/WM contrast, image sharpness, lesion conspicuity, preference for diagnosing abnormal enhancement, and overall intracranial image quality), comparable in 1 of 10 metrics (motion artifacts), and inferior in 2 of 10 metrics (susceptibility artifacts, overall extracranial image quality) related to magnetic susceptibility (P < .05). Interprotocol comparison confirmed relatively higher SNR and GM/WM contrast for partial Fourier and TSE protocol groups, respectively (P < .05). CONCLUSIONS: Spiral 2D T1 spin-echo for routine structural brain MR imaging is feasible in the clinic with conventional scanners and was preferred by neuroradiologists for overall postcontrast intracranial evaluation.
Asunto(s)
Encéfalo/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Neuroimagen/métodos , Adulto , Anciano , Artefactos , Femenino , Humanos , Aumento de la Imagen/métodos , Masculino , Persona de Mediana EdadRESUMEN
To evaluate the representativeness of controls in an ongoing, population-based, case-control study of birth defects in 10 centers across the United States, researchers compared 1997-2003 birth certificate data linked to selected controls (n = 6,681) and control participants (n = 4,395) with those from their base populations (n = 2,468,697). Researchers analyzed differences in population characteristics (e.g., percentage of births at > or =2,500 g) for each group. Compared with their base populations, control participants did not differ in distributions of maternal or paternal age, previous livebirths, maternal smoking, or diabetes, but they did differ in other maternal (i.e., race/ethnicity, education, entry into prenatal care) and infant (i.e., birth weight, gestational age, and plurality) characteristics. Differences in distributions of maternal, but not infant, characteristics were associated with participation by selected controls. Absolute differences in infant characteristics for the base population versus control participants were < or =1.3 percentage points. Differences in infant characteristics were greater at centers that selected controls from hospitals compared with centers that selected controls from electronic birth certificates. These findings suggest that control participants in the National Birth Defects Prevention Study generally are representative of their base populations. Hospital-based control selection may slightly underascertain infants affected by certain adverse birth outcomes.
Asunto(s)
Anomalías Congénitas/epidemiología , Certificado de Nacimiento , Estudios de Casos y Controles , Anomalías Congénitas/prevención & control , Recolección de Datos , Femenino , Registros de Hospitales , Humanos , Recién Nacido , Nacimiento Vivo/epidemiología , Embarazo , Estados Unidos/epidemiologíaRESUMEN
OBJECTIVES: Infant mortality is a major indicator of the health of a nation. We analyzed recent patterns and trends in U.S. infant mortality, with an emphasis on two of the greatest challenges: (1) persistent racial and ethnic disparities and (2) the impact of preterm and low birthweight delivery. METHODS: Data from the national linked birth/infant death datasets were used to compute infant mortality rates per 100,000 live births by cause of death (COD), and per 1,000 live births for all other variables. Infant mortality rates and other measures of infant health were analyzed and compared. Leading and preterm-related CODs, and international comparisons of infant mortality rates were also examined. RESULTS: Despite the rapid decline in infant mortality during the 20th century, the U.S. infant mortality rate did not decline from 2000 to 2005, and declined only marginally in 2006. Racial and ethnic disparities in infant mortality have persisted and increased, as have the percentages of preterm and low birthweight deliveries. After decades of improvement, the infant mortality rate for very low birthweight infants remained unchanged from 2000 to 2005. Infant mortality rates from congenital malformations and sudden infant death syndrome declined; however, rates for preterm-related CODs increased. The U.S. international ranking in infant mortality fell from 12th place in 1960 to 30th place in 2005. CONCLUSIONS: Infant mortality is a complex and multifactorial problem that has proved resistant to intervention efforts. Continued increases in preterm and low birthweight delivery present major challenges to further improvement in the infant mortality rate.
Asunto(s)
Mortalidad Infantil/tendencias , Causas de Muerte/tendencias , Centers for Disease Control and Prevention, U.S. , Femenino , Disparidades en el Estado de Salud , Disparidades en Atención de Salud , Humanos , Lactante , Mortalidad Infantil/etnología , Recién Nacido de Bajo Peso , Recién Nacido , Recien Nacido Prematuro , Embarazo , Estados Unidos/epidemiologíaRESUMEN
Maternal tobacco use during pregnancy has been linked to a host of negative infant and child outcomes, including low birthweight, preterm birth, and various birth defects (1-5). The 2003 revision of the U.S. Standard Certificate of Live Birth included new and modified items on maternal cigarette smoking before and during pregnancy. The 2016 natality data file is the first for which this information is available for all states and the District of Columbia (D.C.). This report presents the prevalence of cigarette smoking at any time during pregnancy among women who gave birth in 2016 in the United States by state of residence as well as maternal race and Hispanic origin, age, and educational attainment.
Asunto(s)
Fumar Cigarrillos/epidemiología , Adolescente , Adulto , Distribución por Edad , Fumar Cigarrillos/etnología , Escolaridad , Femenino , Humanos , Persona de Mediana Edad , Embarazo , Resultado del Embarazo , Estados Unidos , Adulto JovenRESUMEN
Trends in preterm-related causes of death were examined by maternal race and ethnicity. A grouping of preterm-related causes of infant death was created by identifying causes that were a direct cause or consequence of preterm birth. Cause-of-death categories were considered to be preterm-related when 75 percent or more of total infant deaths attributed to that cause were deaths of infants born preterm, and the cause was considered to be a direct consequence of preterm birth based on a clinical evaluation and review of the literature. In 2004, 36.5 percent of all infant deaths in the United States were preterm-related, up from 35.4 percent in 1999. The preterm-related infant mortality rate for non-Hispanic black mothers was 3.5 times higher and the rate for Puerto Rican mothers was 75 percent higher than for non-Hispanic white mothers. The preterm-related infant mortality rate for non-Hispanic black mothers was higher than the total infant mortality rate for non-Hispanic white, Mexican, and Asian or Pacific Islander mothers. The leveling off of the U.S. infant mortality decline since 2000 has been attributed in part to an increase in preterm and low-birthweight births. Continued tracking of preterm-related causes of infant death will improve our understanding of trends in infant mortality in the United States.
Asunto(s)
Etnicidad , Mortalidad Infantil/tendencias , Nacimiento Prematuro/mortalidad , Grupos Raciales , Femenino , Humanos , Mortalidad Infantil/etnología , Recién Nacido , Embarazo , Nacimiento Prematuro/etnología , Estados Unidos/epidemiologíaRESUMEN
KEY FINDINGS: Infant mortality is considered a basic measure of public health for countries around the world (1-3). Over the past decade, the overall infant mortality rate in the United States has improved, declining 15% from 6.86 infant deaths per 1,000 live births in 2005-a recent high-to 5.82 in 2014 (4). Over the years, many efforts have been made to understand and lower infant mortality (4,5). This report examines the 2014 linked birth/infant death data from the National Vital Statistics System (NVSS) to describe trends in infant mortality in the United States by race and Hispanic origin, state, and leading causes of infant deaths from 2005 through 2014.
Asunto(s)
Mortalidad Infantil/tendencias , Humanos , Lactante , Mortalidad Infantil/etnología , Recién Nacido , Estados Unidos/epidemiologíaRESUMEN
The number of births in the United States increased by 1% between 2013 and 2014, to a total of 3 988 076. The general fertility rate rose 1% to 62.9 births per 1000 women. The total fertility rate also rose 0.3% in 2014, to 1862.5 births per 1000 women. The teenage birth rate fell to another historic low in 2014, 24.2 births per 1000 women. The percentage of all births to unmarried women declined to 40.2% in 2014, from 40.6% in 2013. In 2014, the cesarean delivery rate declined to 32.2% from 32.7% in 2013. The preterm birth rate declined for the seventh straight year in 2014 to 9.57%; the low birth weight rate was unchanged at 8.00%. The infant mortality rate decreased to a historic low of 5.82 infant deaths per 1000 live births in 2014. The age-adjusted death rate for 2014 was 7.2 deaths per 1000 population, down 1% from 2013. Crude death rates for children aged 1 to 19 years did not change significantly between 2013 and 2014. Unintentional injuries and suicide were, respectively, the first and second leading causes of death in this age group. These 2 causes of death jointly accounted for 46.5% of all deaths to children and adolescents in 2014.
Asunto(s)
Causas de Muerte , Estadísticas Vitales , Adolescente , Niño , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Embarazo , Estados UnidosRESUMEN
Objectives-This report presents 2015 data on U.S. births according to a wide variety of characteristics. Data are presented for maternal age, live-birth order, race and Hispanic origin, marital status, attendant at birth, method of delivery, period of gestation, birthweight, and plurality. Selected data by mother's state of residence and birth rates by age and race of father also are shown. Trends in fertility patterns and maternal and infant characteristics are described and interpreted. Methods-Descriptive tabulations of data reported on the birth certificates of the 3.98 million births that occurred in 2015 are presented. Results-In 2015, 3,978,497 births were registered in the United States, down less than 1% from 2014. The general fertility rate was 62.5 per 1,000 women aged 15-44, a decline of 1% from 2014. The birth rate for teenagers aged 15-19 fell 8% in 2015, to 22.3 per 1,000 females. Birth rates declined for women in their 20s but increased for women in their 30s and early 40s. The total fertility rate (estimated number of births over a woman's lifetime) declined to 1,843.5 births per 1,000 women in 2015. The birth rate for unmarried women declined for the seventh straight year to 43.5 per 1,000. The cesarean delivery rate declined for the third year in a row to 32.0%. The preterm birth rate increased slightly from 2014, to 9.63% in 2015, as did the rate of low birthweight (8.07% in 2015). The twin birth rate declined to 33.5 per 1,000; the triplet and higher-order multiple birth rate was down 9% to 103.6 per 100,000.
Asunto(s)
Tasa de Natalidad/tendencias , Orden de Nacimiento , Tasa de Natalidad/etnología , Peso al Nacer , Parto Obstétrico/métodos , Etnicidad/estadística & datos numéricos , Femenino , Edad Gestacional , Humanos , Recién Nacido de Bajo Peso , Recién Nacido , Recien Nacido Prematuro , Masculino , Estado Civil , Edad Materna , Progenie de Nacimiento Múltiple/estadística & datos numéricos , Edad Paterna , Embarazo , Estados Unidos/epidemiologíaRESUMEN
KEY FINDINGS: Data from the National Vital Statistics System. The mean age of mothers has increased from 2000 to 2014 for all birth orders, with age at first birth having the largest increase, up from 24.9 years in 2000 to 26.3 years in 2014. Increases in the average age for all birth orders were most pronounced from 2009 to 2014. In 2014, Asian or Pacific Islander mothers had the oldest average age at first birth (29.5 years), while American Indian or Alaska Native mothers had the youngest (23.1 years). Mean age at first birth increased in all states and the District of Columbia (D.C.) from 2000 to 2014, but D.C. (3.4 years) and Oregon had the largest increases (2.1 years).
Asunto(s)
Edad Materna , Adulto , Orden de Nacimiento , Femenino , Humanos , Embarazo , Grupos Raciales/estadística & datos numéricos , Características de la Residencia/estadística & datos numéricos , Estados Unidos/epidemiologíaRESUMEN
KEY FINDINGS: â¢The teen birth rate declined to another historic low for the United States in 2015, down 8% from 2014 to 22.3 births per 1,000 females aged 15-19. â¢The birth rates for teenagers aged 15-17 and 18-19 declined in 2015 to 9.9 and 40.7, respectively, which are record lows for both groups. â¢In 2015, birth rates declined to 6.9 for Asian or Pacific Islander, 16.0 for non-Hispanic white, 25.7 for American Indian or Alaska Native, 31.8 for non-Hispanic black, and 34.9 for Hispanic female teenagers aged 15-19. â¢Birth rates fell to record lows for nearly all race and Hispanic-origin groups of females aged 15-19, 15-17, and 18-19 in 2015. The birth rate for teenagers aged 15-19 has fallen almost continuously since 1991, reaching historic lows for the nation every year since 2009 (1-4). Despite declines in all racial and ethnic groups, teen birth rates continue to vary considerably by race and ethnicity. Moreover, the U.S. teen birth rate remains higher than in other industrialized countries (5). Childbearing by teenagers continues to be a matter of public concern. This report presents the recent and long-term trends and disparity in teen childbearing by race and Hispanic origin.
Asunto(s)
Tasa de Natalidad/tendencias , Índice de Embarazo/tendencias , Embarazo en Adolescencia/estadística & datos numéricos , Adolescente , Distribución por Edad , Tasa de Natalidad/etnología , Femenino , Humanos , Embarazo , Índice de Embarazo/etnología , Embarazo en Adolescencia/etnología , Estados Unidos/epidemiologíaRESUMEN
The U.S. infant mortality rate (IMR) increased from 6.8 infant deaths per 1,000 live births in 2001 to 7.0 in 2002, the first increase in more than 40 years. From 2001 to 2002, IMR increased for very low birthweight infants as well as for preterm and very preterm infants. Although IMR for very low birthweight infants increased, most of the increase in IMR from 2001 to 2002 was due to a change in the distribution of births by birthweight and, more specifically, to an increase in infants born weighing less than 750 grams. The majority of infants born at less than 750 grams die within the first year of life; thus, these births contribute disproportionately to overall IMR. Increases in births at less than 750 grams occurred fornon-Hispanic white, non-Hispanic black, and Hispanic women. Most of the increase occurred among mothers 20 to 34 years of age. Although multiple births contributed disproportionately, most of the increase in births at less than 750 grams occurred among singletons. Three hypotheses were evaluated to assess their possible impact on the increase in less than 750-gram births: possible changes in (1) the reporting of births or fetal deaths, (2) the risk profile of births, and (3) medical management of pregnancy. Although each of these factors may have contributed to the increase, the relative effects of these and other factors remain unclear. More detailed studies are needed to further explain the 2001-2002 infant mortality increase.
Asunto(s)
Mortalidad Infantil/tendencias , Tasa de Natalidad/etnología , Tasa de Natalidad/tendencias , Peso al Nacer , Causas de Muerte , Bases de Datos Factuales , Etnicidad/estadística & datos numéricos , Femenino , Humanos , Recién Nacido , Masculino , Edad Materna , Embarazo , Estados Unidos/epidemiologíaRESUMEN
KEY FINDINGS: The highest percentages of births occurred during the morning and midday hours. Births on Saturday and Sunday were more likely to occur in the late evening and early morning hours than births Monday through Friday. Compared with induced vaginal deliveries and noninduced vaginal deliveries, cesarean deliveries were the least likely to occur during the evening and early morning. Noninduced vaginal births were more likely than cesarean and induced vaginal births to occur in the early morning. Cesarean deliveries with no trial of labor were much more concentrated during the day than were cesarean deliveries with a trial of labor. Births delivered in hospitals and all births show similar time-of-day patterns.
Asunto(s)
Certificado de Nacimiento , Parto Obstétrico/estadística & datos numéricos , Parto , Cesárea/estadística & datos numéricos , Trabajo de Parto Inducido/estadística & datos numéricos , Factores de Tiempo , Estados Unidos/epidemiologíaRESUMEN
Tardive dystonia (TDt), a persistent dystonia associated with exposure to neuroleptic drugs, is an uncommon disorder. It differs from tardive dyskinesia (TDk) in epidemiology, clinical features, risk factors, pathophysiology, course, prognosis, and treatment outcome. TDt seems to develop faster and is more painful, distressing, and disabling than tardive dyskinesia. In this article, evidence is reviewed on the face, descriptive, construct, and predictive validity of this iatrogenic complication of antipsychotic drugs. It is suggested that TDt should not be lumped together with TDk. It deserves a separate nosological status as an independent diagnostic category. The subclassification of TDt into various subtypes based on coexistence of other movement disorders is suggested.
Asunto(s)
Antipsicóticos/efectos adversos , Distonía/inducido químicamente , Distonía/diagnóstico , Adulto , Diagnóstico Diferencial , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Pronóstico , Factores de Riesgo , Factores de TiempoRESUMEN
Clinical, pathologic, and immunologic features of two patients with progressive multifocal leukoencephalopathy and multiple coexisting central nervous system infections are presented. Both showed impaired cell-mediated immunity whereas immunoglobulins were normal, suggesting that defective cellular rather than humoral immunity predisposes to progressive multifocal leukoencephalopathy. Continued neurologic deterioration might be due not only to progression of the condition but also to simultaneous opportunistic bacterial and fungal infections that may be amenable to treatment. Unusual features in case 1 included striking neurologic remission for 8 months and a positive brain scan corresponding to a large demyelinated lesion in the frontal lobe.
Asunto(s)
Encefalopatías/complicaciones , Infecciones/complicaciones , Leucoencefalopatía Multifocal Progresiva/complicaciones , Encefalopatías/inmunología , Encefalopatías/patología , Cerebelo/patología , Criptococosis/patología , Lóbulo Frontal/patología , Humanos , Inmunidad Celular , Leucoencefalopatía Multifocal Progresiva/inmunología , Leucoencefalopatía Multifocal Progresiva/patología , Masculino , Meningitis/complicaciones , Meningitis/patología , Persona de Mediana Edad , Papillomaviridae , Lóbulo Parietal/patología , Polyomaviridae , Lóbulo Temporal/patologíaRESUMEN
Treatment of 6H-1,2,4-oxadiazin-3(2H)-one-5(4H)-thione (2) with hydroxylamine, hydrazine, methylamine, or benzylamine afforded the corresponding N5-substituted 5-amino-6H-1,2,4-oxadiazin-3(2H)-ones 3c-f. Refluxing a dioxane solution of 6H-1,2,4-oxiazine-3,5(2H,4H)-dione (1) with benzylamine or aminodiphenylmethane and hexamethyldisilazane in the presence of ammonium sulfate gave 5-benzylamino-6H-1,2,4-oxadiazin-3(2H)-one (3f) and the corresponding 5-diphenylmethylamino derivative 3g. Reaction of 1 with methyl iodide, benzyl chloride, dihydropyran, dihydrofuran, or benzyloxycarbonyl chloride afforded the corresponding 2-substituted 6H-1,2,4-oxadiazine-3,5(2H,4H)-diones 6a-e. Reaction of 2-methyl-6H-1,2,4-oxadiazine-3,5(2H,4H)-dione (6a) or the corresponding 2-benzyl derivative 6b with phosphorus pentasulfide in dioxane gave 2-methyl-6H-1,2,4-oxadiazin-3(2H)-one-5(4H)-thione (8a) and the corresponding 2-benzyl derivative 8b, respectively. Reaction of 8a with ammonia in dioxane afforded 2-methyl-5-amino-6H-1,2,4-oxadiazin-3(2H)-one (9). The degree of in vitro activity and the presence of antibacterial activity in the urine of animals given 5-amino-6H-1,2,4-oxadiazin-3(2H)-one (3a) by oral route of administration prompted selection of this compound for further study.
Asunto(s)
Oxazinas/síntesis química , Animales , Antiinfecciosos/síntesis química , Antiinfecciosos/farmacología , Antiinfecciosos/orina , Antivirales/síntesis química , Ratones , Pruebas de Sensibilidad Microbiana , Oxazinas/farmacología , Oxazinas/orinaRESUMEN
A series of 14 vinylureidopenicillins and a series of 9 ureidopenicillins were prepared by reaction of 6-aminopenicillanic acid with vinyl isocyanates and isocyanates. These compounds were evaluated for their potential to protect ruminants against lactic acidosis. The compounds were tested for inhibition of in vitro ruminal lactic and propionic acid production, and six compounds inhibited lactic acid production to less than 10% of control at doses of 0.31 microgram/mL or lower, whereas they did not inhibit propionic acid production at doses greater than 10 micrograms/mL. The most active compounds also were screened for general antibacterial activity and were found to be weakly active against Gram-positive bacteria. The structure--activity relationships are discussed for both series. Triethylammonium 6-[3[2-(4-tert-butylphenyl)vinyl]ureido]penicillanate (4) was chosen for evaluation as an inhibitor of intraruminal lactic acidosis in vivo.