Reproductive disorders in dairy cattle: I. Respective influence of herds, seasons, milk yield and parity

This study was performed in two large dairy units (with 130 and 213 calving cows each) during one year. The objectives were to investigate 1) epidemiological patterns of main post-partum reproductive disorders (metritis, post-partum and post-service anestrus, repeat breeding and embryonic death) and 2) the impact of herd, calving season, milk yield and parity on these patterns. Approximately 20% of the cows in both herds were not affected by any of the disorders. Prevalence of metritis was high (32 to 44%) and appeared influenced by the herds' conditions interacting with calving months and milk yield effects. Cyclic post-partum anestrus incidence was also essentially affected by the herd effect with an added seasonal interaction. Other disorders in both herds were also primarily subjected to the seasonal effect. Individual milk yield and parity only marginally affected the epidemiological patterns. We concluded that even in similar environmental conditions, no general patterns of incidence of reproductive disorders can be drawn and that they are essentially dependent on the characteristics of each herd management.     

Determination of the minimal inhibitory concentration of Amphotericin B and Miconazole for 21 strains of Aspergillus

The susceptibility of 21 strains ofAspergillus (11 ofA. fumigatus, 8 ofA. niger, and 2 ofA. flavus) isolated from human pathologic specimens to Amphotericin B and Miconazole has been comparatively studied. Determination of the minimal inhibitory concentration of both drugs in a liquid medium showed a noticeably variability for the different strains. The values obtained for Amphotericin B varied between 0.25g/ml (2 strains) and 1.25g/ml (5 strains) after 48 hours, and between 1.25g/ml (1 strain) and 50g/ml (1 strain) after 10 days. For Miconazole the results varied between 0.1g/ml (1 strain) and 25g/ml (1 strain) after 48 hours of incubation, and between 0.5g/ml (5 strains) and > 100g/ml after 10 days. The variability of these results indicates the usefulness of carrying ourin vitro sensitivity studies whenever it is possible.     

Three new species of penicillium

Three new species of microfungi belonging to the genus Penicillium Link ex Fries are described and illustrated. All but one have been isolated from the atmosphere of las Palmas, capital city of the island of Gran Canaria (Canary Islands, Spain). They clearly differ from all species of the genus described so far and are, therefore, described and proposed as new species: Penicillium hispanicum sp. nov., Penicillium grancanariae sp. nov., and Penicillium palmensis sp. nov.     

Inactivation by ammonia of the photosynthetic reduction of nitrate in Nostoc muscorum particles.

Ammonia, as well as other uncouplers of photophosphorylation, strongly inhibit the photosynthetic reduction of nitrate by particles of the blue-green alga Nostoc muscorum. The enzyme responsible for nitrate reduction, nitrate reductase, can be reversibly inactivated by reduction in a ferredoxin-dependent reaction. Nitrate protects against this inactivation, and molecular oxygen restores the original activity.     

Substrate selectivity of squalene synthetase.

Six 1-3H-labeled analogues of farnesyl pyrophosphate have been studied as potential substrates for yeast and rat liver squalene synthetases: 2-methylfarnesyl pyrophosphate (4), 3-demethylfarnesyl pyrophosphate (5), 7,11-dimethyl-3-ethyl-2,6,10-dodecatrienyl pyrophosphate (6), 6,7,10,11-tetrahydrofarnesyl pyrophosphate (7), 4-methylthiofarnesyl pyrophosphate (8), and 4-fluorofarnesyl pyrophosphate (9). Analogues 4 and 5 are enzymatically incorporated into 11-methylsqualene (10) and 10-demethylsqualene (11), respectively, even if no farnesyl pyrophosphate is added to the incubations. None of the other analogues gives nonpolar products with either the yeast or liver enzymes. No tritium is enzymatically released to the medium from any of the analogues, indicating that they are not accepted at the first (proton exchanging) site. The data rule out formation of dead-end presqualene pyrophosphate products with analogues as first, but not as second, substrates. Implications of these results for the enzyme active-site topology and mechanism are discussed.     

A sensitive fluorimetric microassay for the determination of glutathione peroxidase activity. Application to human blood platelets

The method proposed for measuring glutathione peroxydase (GSH-Px) activity is based on the determination of oxidized glutathione (GSSG) using o-phtalaldehyde (OPT) as a fluorescent reagent. This method makes it possible to study the kinetics of both substrates (peroxide and reduced glutathione, GSH), and allosteric kinetics were found for GSH, with human platelets as the source of GSH-Px. Different methods for platelet disruption were compared. The reference values obtained for GSH-Px activity in human blood platelets by this fluorimetric procedure and the conventional enzymatic method were very similar and significantly higher than those previously reported; the reasons for this difference are discussed.     

Transferrin, somatomedins and growth

Plasma transferrin is significantly positively correlated to the growth velocity in normal children and children with various growth disorders. In hypopituitary dwarfs, both plasma transferrin and somatomedin are significantly lower than in controls. Acute variations of the plasma transferrin levels could be involved in the regulation of the GH secretion by a feedback mechanism. Yet, transferrin is neither a somatomedin or a somatomedin-binding protein, and the mechanisms relating growth to transferrin remain unknown.     

Use of fluorescent probes in the study of phospholipid--sterol bilayers.

1. The transfer of excitation energy between the fluorescent probes 1,6-diphenylhexa-1,3,5-triene and 12-(9-anthroyl)stearic acid and the cholesterol analogue cholesta-4,6-dien-3-one in phosphatidylcholine liposomes has been investigated. 2. The results indicate that probes and steroid are randomly distributed in the bilayer at steroid concentrations up to 35 mol%. 3. The degree of polarization of diphenylhexatriene fluorescence increases with increasing cholesterol content. Other sterols, differing in structure in the region of the polar group or in the side chain at position-17, produce similar but not identical effects. 4. the results are consistent with the proposal that diphenylhexatriene gives a general picture of the state of the bilayer and that there is no segregation of sterols in liquid-crystalline phosphatidylcholine bilayers.     

Four new species of Penicillium isolated from the air

Four new species of Penicillium Link ex Fries are described and illustrated. All of them but one have been isolated from the atmosphere in Madrid, Spain. They clearly differ from all species of the genus described so far and are, therefore, described and proposed as new taxa: Penicillium aurantio-flammiferum sp. nov., Penicillium gallaicum sp. nov., Penicillium granatense sp. nov., and Penicillium ilerdanum sp. nov.     

Statistical-mechanical theory of passive transport through partially sieving or leaky membranes

The basic equations for multicomponent transport through partially sieving or leaky membranes are discussed from a statistical-mechanical viewpoint. They have the same mathematical form as the corresponding equations for open membranes, but differ in a discontinuous way from the equations for semipermeable membranes (since a "leak" in a semipermeable membrane constitutes a discontinuous or singular perturbation). Partially sieving membranes can be made to mimic semipermeable behavior through the introduction of characteristic time scales. They may approximate semipermeable behavior at short times, but always deviate at longer times.