Monensin, virginiamycin, and flavomycin in a no-roughage finishing diet fed to zebu cattle.

Two experiments were designed to evaluate the effects of monensin, virginiamycin, and flavomycin on growth performance, carcass characteristics, apparent total tract nutrient digestibility, and rumen fermentation of zebu cattle fed a no-roughage finishing diet (whole shelled corn [WSC] based). In Exp. 1, 100 crossbred bulls (; 392 kg [SD 46.8] average initial BW) were blocked by initial BW in a 101-d feedlot trial. Five treatments were evaluated using 4 pens per treatment (5 bulls/pen): monensin at 30 mg/kg DM, virginiamycin at 25 mg/kg DM, monensin at 20 mg/kg DM plus virginiamycin at 25 mg/kg DM, flavomycin at 4.4 mg/kg DM, and monensin at 20 mg/kg DM plus flavomycin at 2.2 mg/kg DM. There were no differences in growth performance (final BW, ADG, DMI, and G:F; ≥ 0.527) and carcass characteristics (HCW, dressing percent, and 12th-rib fat; ≥ 0.235) among treatments. In Exp. 2, 7 ruminally fistulated steers were used in a 7 × 7 Latin square design to evaluate the 5 treatments of Exp. 1 and 2 additional treatments: monensin at 30 mg/kg DM plus virginiamycin at 25 mg/kg DM and monensin at 20 mg/kg DM plus flavomycin at 4.4 mg/kg DM. Experimental periods were 14 d in length (9 d of adaptation and 5 d of measurements). Apparent total tract DM, OM, CP, and NDF digestibilities were similar among treatments ( ≥ 0.224). There was no treatment effect ( ≥ 0.253) in rumen fermentation responses (ruminal pH, rumen ammonia nitrogen, VFA, and number of protozoa). In conclusion, no evidence of benefits to cattle fed a no-roughage WSC-based diet was found to support the use of monensin combined with virginiamycin or flavomycin in the doses tested herein.

Efeitos de fontes e formas de processamento do amido na utilização de nutrientes e parâmetros ruminais de vacas em lactação / Effects of starch sources and processing on nutrient digestibility and ruminal parameters of lactating cows

Cinco vacas holandesas pluríparas, com cânulas no rúmen e no duodeno, foram distribuídas em delineamento de quadrado latino 5 x 5. As vacas foram submetidas a cinco rações experimentais contendo 40 por cento de cana-de-açúcar, 60 por cento de concentrado e cerca de 30 por cento de amido. As rações diferiram quanto ao processamento ou à fonte principal do amido utilizado: milho grosseiramente moído, milho finamente moído, milho floculado a 310g/l, milho floculado a 360g/l ou raspa de mandioca. Não houve diferença (P>0,05) no consumo de matéria seca entre os tratamentos. A digestibilidade ruminal do amido foi maior na ração que continha raspa de mandioca. As digestibilidades ruminal da fibra em detergente neutro e da fibra em detergente ácido não diferiram entre os tratamentos. Os dados médios de pH ruminal se mantiveram acima de 6,0, exceto às 2 e às 4h após a alimentação com a dieta que continha raspa de mandioca. Não houve efeito significativo dos tratamentos sobre a concentração de ácidos graxos voláteis totais. O processo de floculação promoveu aumento da digestibilidade do amido do milho, em relação à moagem de forma grosseira. A digestibilidade ruminal do amido presente na raspa de mandioca foi maior do que a do milho, independentemente da forma de processamento utilizada.

Five multiparous lactating Holsteins cows, cannulated in the rumen and proximal duodenum, were used in a 5 x 5 latin square. Cows were fed a 40:60 forage: concentrate diet (40 percent fresh sugar cane and 60 percent concentrate). Diets were formulated to have 30 percent of starch and treatments were starch sources and ration processing forms: cracked corn, finely ground corn, flaked corn at 310g/l, flaked corn at 360g/l, or cassava scrapings. No difference (P>0.05) was observed among treatments for dry matter intake. Starch ruminal digestibility was higher for cassava scrapings treatment. NDF and ADF digestibility were similar among treatments. Average values of ruminal pH were above 6, except at 2 and 4h after feeding the cassava diet. There was no effect of treatment on concentrations of total volatile fatty acids. The flocculation process increased corn starch digestibility. Ruminal degradability of the cassava scrapings starch was higher than corn, without effect of processing form.

Fontes nitrogenadas em rações contendo bagaço de cana-de-açúcar hidrolizado no desempenho de bovinos confinados em terminação / Nitrogen source on performance of feedlot young bulls fed hydrolyzed sugarcane bagasse diets

Oitenta e um machos não castrados das raças Nelore (27), Canchim (27) e Holandesa (27), com peso médio inicial de 360kg e idade média de 18 meses, foram utilizados para avaliar os efeitos da substituição de fonte de proteína verdadeira (farelo de soja), por nitrogênio não protéico (NNP), uréia ou amiréia (fonte de nitrogênio não protéico de suposta liberação gradativa) sobre o desempenho de bovinos confinados. O delineamento experimental foi o de blocos inteiramente ao acaso com três animais por baia e nove baias por tratamento. Os blocos foram delineados de acordo com o peso inicial e na raça. As rações experimentais continham BTPV (45 por cento MS da dieta) e BIN (5 por cento MS da dieta) como fontes de volumosos e 50 por cento de concentrado. Os tratamentos consistiam de: 1) concentrado contendo farelo de soja (FS); 2) concentrado contendo uréia e 3) concentrado contendo amiréia (A-150S). O consumo de matéria seca (CMS) foi de 8,99; 7,43 e 7,69kg/dia, o ganho de peso diário (GPD) foi de 0,983; 0,368 e 0,404kg/dia e a conversão alimentar (CA) 9,56; 20,14 e 19,54kg MS/kg de ganho para os tratamentos FS, uréia e A-150S, respectivamente. As rações com FS apresentaram proporcionalmente maior (P<0,01) CMS e maior GPD e melhor CA em relação aos tratamentos uréia e A-150S. As rações com uréia e A-150S não diferiram (P>0,05) entre si. A substituição do FS por fontes de NNP reduziu o desempenho de bovino de corte em terminação.

Eighty-one young bulls (27 Nellore, 27 Canchim, and 27 Holstein), averaging 18-month-old and weighting 360kg of initial body weight (BW), were used to evaluate the effects of nitrogen sources on feedlot performance. Treatments were assigned in a completely randomized block design using three steers per stall and nine per treatment. Blocks were defined by initial BW and breed. Experimental treatments were: 1) soybean meal, 2) urea, and 3) starea. Diets were isonitrogenous and isoenergetic composed by 50 percent concentrate and 50 percent forage (45 percent hydrolyzed sugarcane bagasse + 5 percent in natura sugarcane bagasse). Dry matter intakes (DMI) were 8.99, 7.43, and 7.69kg/day, average daily gains (ADG) were 0.983, 0.368, and 0.404kg/day and feed efficiencies were 9.56, 20.14, and 19.54kg DM/kg of gain for soybean meal, urea and starea treatments, respectively for steers fed. Diets with soybean meal showed proportionally higher (P<0.01) DMI, higher average daily gain and better feed efficiency compared to urea and starea diets. No differences (P>0.05) between urea and starea treatments were observed. Replacement of soybean meal by nonprotein nitrogen sources decreased the finishing beef steers performance.

Distribution and genetic diversity of tomato-infecting begomoviruses in Brazil.

Tomato-infecting begomoviruses have been reported throughout Brazil since the introduction of the B biotype of Bemisia tabaci. Here, we report a large scale survey on the distribution and genetic diversity of tomato-infecting begomoviruses. Tomato samples with typical begomovirus symptoms were collected in seven different states, comprising the major tomato growing areas of the country. Viruses were detected by polymerase chain reaction (PCR) using universal primers for the genus Begomovirus. PCR-amplified fragments were cloned and sequenced. Based on sequence comparisons and phylogenetic analyses, at least seven previously undescribed species of begomoviruses were found. Four of the new viruses were found exclusively in the Southeastern states, two exclusively in the Northeastern states, and one was found in both regions. Sequence comparisons reveal strong evidence of recombination among the Brazilian begomoviruses. Together, the results indicate the existence of a high degree of pre-existing genetic diversity among tomato-infecting begomoviruses in Brazil and suggest that these viruses have emerged after being transferred from natural hosts to tomatoes, due to the introduction into Brazil of a novel polyfagous biotype of the whitefly vector.

Nerve-muscle interactions during flight muscle development in Drosophila.

During Drosophila pupal metamorphosis, the motoneurons and muscles differentiate synchronously, providing an opportunity for extensive intercellular regulation during synapse formation. We examined the existence of such interactions by developmentally delaying or permanently eliminating synaptic partners during the formation of indirect flight muscles. When we experimentally delayed muscle development, we found that although adult-specific primary motoneuron branching still occurred, the higher order (synaptic) branching was suspended until the delayed muscle fibers reached a favourable developmental state. In reciprocal experiments we found that denervation caused a decrease in the myoblast pool. Furthermore, the formation of certain muscle fibers (dorsoventral muscles) was specifically blocked. Exceptions were the adult muscles that use larval muscle fibers as myoblast fusion targets (dorsal longitudinal muscles). However, when these muscles were experimentally compelled to develop without their larval precursors, they showed an absolute dependence on the motoneurons for their formation. These data show that the size of the myoblast pool and early events in fiber formation depend on the presence of the nerve, and that, conversely, peripheral arbor development and synaptogenesis is closely synchronized with the developmental state of the muscle.

Widespread Occurrence of Tomato Geminiviruses in Brazil, Associated with the New Biotype of the Whitefly Vector.

Although tomato golden mosaic virus (TGMV) was reported in Brazil more than 20 years ago (3), tomato-infecting geminiviruses have not been of economic significance in the country until recently. However, a sharp increase in the incidence of geminivirus-like symptoms in tomatoes has been reported in several areas of Brazil since 1994. This has coincided with the appearance of the B biotype of Bemisia tabaci, which, as opposed to the A biotype, readily colonizes solanaceous plants (2). We have isolated geminiviruses from symptomatic tomato plants in the Federal District, in two different areas of the state of Minas Gerais, and in the state of Pernambuco. Tomato plants in these areas showed a variety of symptoms, including yellow mosaic, severe leaf distortion, down-cupping, and epinasty. Whitefly infestation was high in all fields sampled, and in some fields, particularly in Pernambuco, incidence of virus-like symptoms was close to 100%, and no tomatoes of commercial value were harvested (1). Using primer pairs PAL1v1978/PAR1c496 and PCRc1/PBL1v2040 (4), DNA-A and -B fragments were polymerase chain reaction (PCR)-amplified from total DNA extracted from diseased plants, cloned, and sequenced. Sequence comparisons of the PCR fragments indicated the existence of at least six different geminiviruses. The nucleotide sequence homologies for DNA-A fragments ranged from 67 to 80% for the 5' end of the cp gene, and from 44 to 80% for the 5' end of the rep gene. Data base comparisons indicated the viruses are most closely related to TGMV, bean golden mosaic virus from Brazil (BGMV-Br), and tomato yellow vein streak virus (ToYVSV), although homologies were less than 80% for the fragments compared. A similar lack of a close relationship with each other and other geminiviruses was obtained with two DNA-B component PCR products compared, corresponding to the 5' end of the BC1 open reading frame. Infectious, full-length genomic clones from the tomato viruses are being generated for biological and molecular characterization. References: (1) I. C. Bezerra et al. Fitopatol. Bras. 22:331, 1997. (2) F. H. França et al., Ann. Soc. Entomol. Bras. 25:369, 1996. (3) J. C. Matyis et al. Summa Phytopathol. 1:267, 1975. (4) M. R. Rojas et al. Plant Dis. 77:340, 1993.

Patterning the dorsal longitudinal flight muscles (DLM) of Drosophila: insights from the ablation of larval scaffolds.

The six Dorsal Longitudinal flight Muscles (DLMs) of Drosophila develop from three larval muscles that persist into metamorphosis and serve as scaffolds for the formation of the adult fibers. We have examined the effect of muscle scaffold ablation on the development of DLMs during metamorphosis. Using markers that are specific to muscle and myoblasts we show that in response to the ablation, myoblasts which would normally fuse with the larval muscle, fuse with each other instead, to generate the adult fibers in the appropriate regions of the thorax. The development of these de novo DLMs is delayed and is reflected in the delayed expression of erect wing, a transcription factor thought to control differentiation events associated with myoblast fusion. The newly arising muscles express the appropriate adult-specific Actin isoform (88F), indicating that they have the correct muscle identity. However, there are frequent errors in the number of muscle fibers generated. Ablation of the larval scaffolds for the DLMs has revealed an underlying potential of the DLM myoblasts to initiate de novo myogenesis in a manner that resembles the mode of formation of the Dorso-Ventral Muscles, DVMs, which are the other group of indirect flight muscles. Therefore, it appears that the use of larval scaffolds is a superimposition on a commonly used mechanism of myogenesis in Drosophila. Our results show that the role of the persistent larval muscles in muscle patterning involves the partitioning of DLM myoblasts, and in doing so, they regulate formation of the correct number of DLM fibers.

Development of the indirect flight muscle attachment sites in Drosophila: role of the PS integrins and the stripe gene.

Using markers that are expressed at muscle attachment sites, we have examined the early pupal development (first 36 hr) of Indirect Flight Muscle (IFM) attachments in the fruit fly Drosophila melanogaster. Expression of the Drosophila homologs of vertebrate integrins, the Position-Specific (PS) antigens, is known to differentially mark epidermal (PS1alpha) and muscle (PS2alpha) components of the developing IFM attachment sites. During myogenesis, PS2alpha is detected transiently in imaginal myoblasts that fuse with persistent larval muscles to give rise to the Dorsal Longitudinal Muscles (DLMs), but not in myoblasts that fuse de novo to give rise to the Dorso Ventral Muscles. The integrins are not expressed at attachment sites when the muscle fibers first make their appearance (12-20 hr). Following muscle-epidermal contact, PS1 and PS2 are detected at muscle attachment sites. PS1 expression is at the muscle ends and also in the long epidermal processes that connect the developing muscle fibers to their sites of attachment in the epidermis, while PS2 expression is restricted to the muscle ends. Epidermal cells that will contribute to the adult attachment sites are defined as early as the third larval instar. Both anterior and posterior sites of attachment of the IFMs are marked by the expression of reporter beta-galactosidase activity in a P-element line B14.0, which is an insertion at the stripe locus. B14.0 (stripe) is seen in distinct domains in the wing and leg imaginal discs which give rise to the thoracic cuticle. The expression is maintained during pupal development. The B14.0 (stripe) expressing epidermal cells contact the developing muscle fibers, leading to the formation of the myotendon junction. We show that the dorsal and ventral attachment sites of one group of IFMs, the DVMs arise from two different imaginal discs (wing and leg, respectively), which may explain the differential effect of mutations such as bendless on these muscles. Attachment sites for the other group of IFMs, the DLMs, on the other hand, arise from one imaginal disc (wing). B14.0 (stripe) expression defines epidermal cells of the adult attachment sites and is likely to function during early events leading to the formation of muscle-epithelial contacts. The PS integrins are detected at later stages, suggesting a role in the stabilization and maturation of the muscle-epidermal contacts into myotendon junctions.

Hepatitis testing update.

During a 25-year period, four types of hepatitis-causing virus have been identified and can now be evaluated serologically. This final article in this clinical laboratory medicine series reviews routes of virus transmission and persistence and the availability of tests.

Therapeutic drug monitoring: lithium levels.

Lithium has been used in the treatment of mania since 1949. Although its effectiveness is well recognized, the mechanism by which it stabilizes manic behavior is not well understood. In addition, it has some serious toxic properties combined with a narrow therapeutic range. For this reason, monitoring of serum lithium levels is mandatory. Suggested mechanisms of action and protocols for monitoring of serum levels are presented.

DNA technology.

Scientific developments in molecular biology enable clinical laboratory testing to directly examine genetic information coded in biologic specimens. These efforts, accomplished by the use of DNA probe technology in the in situ hybridization and other tests will allow for the specific identification of pathogens; recognition of genetic diseases; and the critical evaluation of the genetic basis of cancer. The authors discuss the concepts and uses of DNA testing.

Human immunodeficiency virus testing: update.

Human immunodeficiency virus (HIV) types 1 and 2 have been associated with the acquired immunodeficiency syndrome (AIDS). The detection of HIV infections is based on the screening of serum samples for the presence of antibodies to HIV proteins. Serum samples that test positive on screening must be assayed by a confirmatory test to provide a definitive report on the presence of HIV infection. This article reviews the currently available screening and confirmatory testing procedures and their limitations.

Group A Streptococcus detection: office versus reference laboratory.

Clinical differentiation between a virus and beta-hemolytic streptococci as a cause of pharyngitis remains difficult. In the physician's laboratory, more rapid procedures using immunologic methods have replaced culture methods, traditionally requiring 2 to 3 days for identification of beta-hemolytic streptococci. Attention to the diagnostic sensitivity and specificity of these procedures will guide appropriate use.

Realistic expectations of laboratory testing.

The ordering, reviewing, and interpreting of laboratory tests require recognition and familiarity with the concepts of normal values, sensitivity, specificity, predictive values, and prevalence. The significance of these test properties in clinical decision-making is explained.

Laboratory instruments for the physician's office laboratory: technology and cost-benefits.

During the past two decades, medicine has witnessed the decentralization of laboratory testing from the hospital into the physician's office. This article focuses on the technical aspects of the instruments now available for laboratory testing in the physician's office. Consideration is given to specific instruments, methods, and cost-benefit.

Blood ethanol testing.

The justification for blood ethanol testing springs from the ubiquitous abuse of alcoholic beverages. Those dealing with patients who abuse alcohol must understand the correlations between dose, time, blood level, and behavior. Enumerated here are the strengths of various testing methods and the requisites for legally defensible testing. The challenge remains to determine blood ethanol levels in such a manner that the results are scientifically valid and legally defensible.

Metastasis of prostate gland adenocarcinoma to penile and scrotal cutaneous tissues.

The metastatic sites of adenocarcinoma of the prostate are well documented. Bone metastasis is the most frequently encountered site. Skin metastasis is rarely reported. Its presence, however, is associated with a poor prognosis. The possible cause of cutaneous spread is discussed in the case report. The possible role that external-beam radiotherapy may play in this setting is also analyzed.