Milk Fever Control Principles: A Review

Three main preventive principles against milk fever were evaluated in this literature review, and the efficacy of each principle was estimated from the results of controlled investigations. Oral calcium drenching around calving apparently has a mean efficacy of 50%–60% in terms of milk fever prevention as well as prevention of milk fever relapse after intravenous treatment with calcium solutions. However, some drenches have been shown to cause lesions in the forestomacs. When using the DCAD (dietary cation-anion difference) principle, feeding rations with a negative DCAD (measured as (Na + K) – (Cl + S)) significantly reduce the milk fever incidence. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a mean RR between 0.19 and 0.35 when rations with a negative versus positive DCAD are compared. The main drawback from the DCAD principle is a palatability problem. The principle of feeding rations low in calcium is highly efficient in milk fever prevention provided the calcium intake in the dry period is kept below 20 g per day. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a very low mean RR (between 0 and 0.20) (daily calcium intake below versus above 20 g/d). The main problem in implementing the low-Ca principle is difficulties in formulating rations sufficiently low in calcium when using commonly available feeds. The use of large doses of vitamin D metabolites and analogues for milk fever prevention is controversial. Due to toxicity problems and an almost total lack of recent studies on the subject this principle is not described in detail. A few management related issues were discussed briefly, and the following conclusions were made: It is important to supply the periparturient cow with sufficient magnesium to fulfil its needs, and to prevent the dry cows from being too fat. Available information on the influence of carbohydrate intake, and on the effect of the length of the dry period and prepartum milking, is at present insufficient to include these factors in control programmes.     

A New PCR-Based Approach Indicates the Range of Clonorchis sinensis Now Extends to Central Thailand

Differentiation of the fish-borne trematodes belonging to the Opisthorchiidae, Heterophyidae and Lecithodendriidae is important from a clinical and epidemiological perspective, yet it is impossible to do using conventional coprological techniques, as the eggs are morphologically similar. Epidemiological investigation therefore currently relies on morphological examination of adult worms following expulsion chemotherapy. A PCR test capable of amplifying a segment of the internal transcribed spacer region of ribosomal DNA for the opisthorchiid and heterophyid flukes eggs taken directly from faeces was developed and evaluated in a rural community in central Thailand. The lowest quantity of DNA that could be amplified from individual adults of Opisthorchis viverrini, Clonorchis sinensis and Haplorchis taichui was estimated at 0.6 pg, 0.8 pg and 3 pg, respectively. The PCR was capable of detecting mixed infection with the aforementioned species of flukes under experimental conditions. A total of 11.6% of individuals in rural communities in Sanamchaikaet district, central Thailand, were positive for ‘Opisthorchis-like’ eggs in their faeces using conventional parasitological detection techniques. In comparison to microscopy, the PCR yielded a sensitivity and specificity of 71.0% and 76.7%, respectively. Analysis of the microscopy-positive PCR products revealed 64% and 23% of individuals to be infected with O. viverrini and C. sinensis, respectively. The remaining 13% (three individuals) were identified as eggs of Didymozoidae, presumably being passed mechanically in the faeces following the ingestion of infected fishes. An immediate finding of this study is the identification and first report of a C. sinensis–endemic community in central Thailand. This extends the known range of this liver fluke in Southeast Asia. The PCR developed herein provides an important tool for the specific identification of liver and intestinal fluke species for future epidemiological surveys.     

Risk of Infection with Leishmania spp. in the Canine Population in the Netherlands

The dog is the main reservoir of Leishmania infantum, the causative agent of visceral leishmaniasis (VL) in humans in Southern Europe. In order to identify the risk of dogs from a Leishmania non-endemic area traveling to a Leishmania -endemic area becoming infected and the risk of transmitting infection to humans in non-endemic areas an investigation was performed, in which the results of a questionnaire were combined with the results of a serologic survey.     

Evaluation of the In Vitro Activity of Tobramycin as Compared with That of Gentamicin Sulfate

The in vitro activity of tobramycin was quantitatively compared with that of gentamicin sulfate against 195 bacterial isolates from clinical material. Tobramycin was found to be twice as active as gentamicin against isolates of Pseudomonas aeruginosa. Conversely, gentamicin proved fourfold more active than tobramycin against isolates of Serratia marcescens. Both drugs were of comparable activity against isolates of Staphylococcus aureus and the majority of the enterobacterial isolates other than S. marcescens. On the basis of the obtained data, the following criteria are proposed for the interpretation of diffusion susceptibility tests with 10-μg discs of gentamicin and tobramycin. Enterobacteriaceae and isolates of S. aureus are designated as susceptible to gentamicin and tobramycin if the zones of inhibition measure 15 mm or more in diameter; zones of 14 mm or less are indicative of resistance. Pseudomonadaceae are interpreted as sensitive to tobramycin and gentamicin if the inhibition zones measure at least 15 and 12 mm in diameter, respectively.     

Characterization of an Unusual Strain of Proteus rettgeri Associated with an Outbreak of Nosocomial Urinary-Tract Infection

An outbreak of nosocomial urinary-tract infection was caused by a strain of Proteus rettgeri that fermented lactose overnight and was resistant to all antimicrobial drugs tested. The nonmotile isolates shared an O (somatic) antigen that differed from those of wild-type P. rettgeri. The organisms proved markedly serum-sensitive. In rats, the isolates elicited an acute interstitial nephritis with associated transient bacteriuria. Attempts to transfer the lac(+) trait and drug-resistance markers to recipient strains of Escherichia coli K-12 failed; exposure of the isolates to acridine orange yielded small numbers of non-lactose-fermenting variants which, however, were still as drug-resistant as before. Epidemiological studies failed to uncover the source of this unique strain and appeared to indicate exogenous spread of infection.     

Purification of p100, a protein antigenically related to the signal transducing G proteins Gt and Gi. Evidence for an adaptin-like protein.

A 100-kDa protein, termed p100, cross-reacts with antisera raised against a synthetic peptide corresponding to the carboxyl-terminal decapeptide of the alpha-subunit of the retinal G protein Gt. p100 is abundantly expressed in liver and, on subcellular fractionation of rat liver homogenates, is distributed between the cytosolic and microsome fractions (Traub, L. M., Evans, W. H., and Sagi-Eisenberg, R. (1990) Biochem. J. 272, 453-458; Udrisar, D., and Rodbell, M. (1990) Proc. Natl. Acad. Sci. U. S. A. 87, 6321-6325). We have now purified p100 to near-homogeneity from rat liver microsomes. The protein was purified approximately 500-fold by ATP extraction followed by a series of four chromatographic steps. Similar to partially purified p100, on two-dimensional electrophoresis, the final preparation contained a major series of five immunoreactive 100-kDa charge isoforms. Partial amino terminus amino acid sequencing of the purified protein revealed that p100 is a previously unidentified protein. Further analysis of the soluble form of p100 showed the protein migrated with an apparent molecular weight of approximately 110,000 on gel filtration, indicating that the soluble protein occurs as a monomeric polypeptide. The soluble form of p100 was also partially purified from rat liver cytosol and amino acid sequencing yielded the same amino-terminal sequence as obtained from the microsome-associated form. The amino-terminal sequence of p100 exhibits significant similarity to the deduced amino-terminal amino acid sequences of both alpha- and gamma-adaptins. Using the amino-terminal sequence from p100, we have raised antipeptide polyclonal antisera. The antisera reacted specifically with the purified 100-kDa protein on immunoblots. With the purified protein and specific antisera now available, it will be possible to explore the physiological role of p100.     

The diabetic rat kidney mediates inosituria and selective urinary partitioning of D-chiro-inositol

Diabetic nephropathy is a serious complication of diabetes mellitus with a pressing need for effective metabolic markers to detect renal impairment. Of potential significance are the inositol compounds, myo-inositol (MI), and the less abundant stereoisomer, D-chiro-inositol (DCI), which are excreted at increased levels in the urine in diabetes mellitus, a phenomenon known as inosituria. There is also a selective urinary excretion of DCI compared to MI. As the biological origins of altered inositol metabolism in diabetes mellitus are unknown, the aim of this study was to determine whether the diabetic kidney was directly responsible. Kidneys isolated from four-week streptozotocin-induced diabetic rats were characterized by a 3-fold reduction in glomerular filtration rate (GFR) compared to matched non-diabetic kidneys. When perfused with fixed quantities of MI (50 µM) and DCI (5 µM) under normoglycemic conditions (5 mM glucose), GFR-normalized urinary excretion of MI was increased by 1.7-fold in diabetic vs. non-diabetic kidneys. By comparison, GFR-normalized urinary excretion of DCI was increased by 4-fold. Perfusion conditions replicating hyperglycemia (20 mM glucose) potentiated DCI but not MI urinary excretion in both non-diabetic and diabetic kidneys. Overall, there was a 2.4-fold increase in DCI urinary excretion compared to MI in diabetic kidneys that was independent of glucose ambience. This increased urinary excretion of DCI and MI in diabetic kidneys occurred despite increased renal expression of the inositol transporters, sodium myo-inositol transporter subtype 1 and 2 (SMIT1 and SMIT2). These findings show that the diabetic kidney primarily mediates inosituria and altered urinary partitioning of MI and DCI. Urinary inositol levels might therefore serve as an indicator of impaired renal function in diabetes mellitus with wider implications for monitoring chronic kidney disease.     

A comparative x-ray study of a nucleoprotamine and DNA complexes with polylysine and polyarginine

The high-humidity X-ray pattern of oriented fibers prepared from salmon spermheads strongly resembles that of DNA in the B form. However, the nucleoprotamine pattern has a more intense first layer line and increased lateral unit-cell dimensions. Complexes of DNA with poly-L -lysine and poly-L -arginine were prepared and photographed at various relative humidities. The most crystalline patterns were obtained at 92% and also indicate DNA in the B form. However, whereas polylysine–DNA, like the spermheads, has a primitive hexagonal cell, polyarginine–DNA, like NaDNA, has three molecules in the unit cell. Polylysine–DNA, but not polyarginine–DNA, also resembles spermheads in having a strong first layer line. All three complexes show increasing intermolecular distance with increasing humidity, but with sharp maxima when photographed in water, which indicates cross-linking between the molecules. Lowering the humidity causes the polylysine–DNA, but not polyarginine–DNA, to change conformation from the B to the C form. The structural implications of these results are discussed in the light of model-building studies and a comparison of calculated and observed X-ray intensities.