Comparative reproductive performance of Saanen and Toggenburg bucks raised under tropical environment.

The objective of this study was to evaluate the effect of breed and age on scrotal measurements and semen characteristics of Saanen and Toggenburg bucks raised under extensive system in the tropic. The study was conducted using Toggenburg and Saanen bucks; the bucks were allocated into two different groups based on breed and age in 2 × 2 factorial completely randomized design. The body weight was determined using a hanging weighing scale expressed in kilogrammes (kg). Scrotal circumference and scrotal length were measured using metal measuring tape. Semen characteristics evaluated were volume, consistency, mass activity and progressive motility, live sperm cells, normal morphology and spermatozoa concentration. The current study found that breed of bucks had no influence on body weight, scrotal circumference, scrotal length, volume, mass activity, progressive motility, live sperm cells and sperm morphology. The study also found that Toggenburg bucks had higher semen consistency and spermatozoa concentration as compared with Saanen bucks. Therefore, it can be concluded that Toggenburg bucks can produce high number of total spermatozoa and as a result higher semen doses for artificial insemination purposes. Further studies with more number of animals are recommended.

X-ray micro-diffraction studies on biological samples at the BioCAT Beamline 18-ID at the Advanced Photon Source.

The small source sizes of third-generation synchrotron sources are ideal for the production of microbeams for diffraction studies of crystalline and non-crystalline materials. While several such facilities have been available around the world for some time now, few have been optimized for the handling of delicate soft-tissue specimens under cryogenic conditions. Here the development of a new X-ray micro-diffraction instrument at the Biophysics Collaborative Access Team beamline 18-ID at the Advanced Photon Source, and its use with newly developed cryo-diffraction techniques for soft-tissue studies, are described. The combination of the small beam sizes delivered by this instrument, the high delivered flux and successful cryo-freezing of rat-tail tendon has enabled us to record data to better than 4 Šresolution. The ability to quickly raster scan samples in the beam allows selection of ordered regions in fibrous samples for markedly improved data quality. Examples of results of experiments obtainable using this instrument are presented.

New clinical pathways for keratoconus.

Pre-2000, the clinical management of keratoconus centred on rigid contact lens fitting when spectacle corrected acuity was no longer adequate, and transplantation where contact lens wear failed. Over the last decade, outcome data have accumulated for new interventions including corneal collagen crosslinking, intracorneal ring implantation, topographic phototherapeutic keratectomy, and phakic intraocular lens implantation. We review the current evidence base for these interventions and their place in new management pathways for keratoconus under two key headings: corneal shape stabilisation and visual rehabilitation.

Multi-wavelength anomalous diffraction using medium-angle X-ray solution scattering (MADMAX).

Proteins are dynamic molecules whose function in virtually all biological processes requires conformational motion. Direct experimental probes of protein structure in solution are needed to characterize these motions. Anomalous scattering from proteins in solution has the potential to act as a precise molecular ruler to determine the positions of specific chemical groups or atoms within proteins under conditions in which structural changes can take place free from the constraints of crystal contacts. In solution, anomalous diffraction has two components: a set of cross-terms that depend on the relative location of the anomalous centers and the rest of the protein, and a set of pure anomalous terms that depend on the distances between the anomalous centers. The cross-terms are demonstrated here to be observable and to provide direct information about the distance between the anomalous center and the center of mass of the protein. The second set of terms appears immeasurably small in the context of current experimental capabilities. Here, we outline the theory underlying anomalous scattering from proteins in solution, predict the anomalous differences expected on the basis of atomic coordinate sets, and demonstrate the measurement of anomalous differences at the iron edge for solutions of myoglobin and hemoglobin.

WAXS studies of the structural diversity of hemoglobin in solution.

Specific ligation states of hemoglobin are, when crystallized, capable of taking on multiple quaternary structures. The relationship between these structures, captured in crystal lattices, and hemoglobin structure in solution remains uncertain. Wide-angle X-ray solution scattering (WAXS) is a sensitive probe of protein structure in solution that can distinguish among similar structures and has the potential to contribute to these issues. We used WAXS to assess the relationships among the structures of human and bovine hemoglobins in different liganded forms in solution. WAXS data readily distinguished among the various forms of hemoglobins. WAXS patterns confirm some of the relationships among hemoglobin structures that have been defined through crystallography and NMR and extend others. For instance, methemoglobin A in solution is, as expected, nearly indistinguishable from HbCO A. Interestingly, for bovine hemoglobin, the differences between deoxy-Hb, methemoglobin and HbCO are smaller than the corresponding differences in human hemoglobin. WAXS data were also used to assess the spatial extent of structural fluctuations of various hemoglobins in solution. Dynamics has been implicated in allosteric control of hemoglobin, and increased dynamics has been associated with lowered oxygen affinity. Consistent with that notion, WAXS patterns indicate that deoxy-Hb A exhibits substantially larger structural fluctuations than HbCO A. Comparisons between the observed WAXS patterns and those predicted on the basis of atomic coordinate sets suggest that the structures of Hb in different liganded forms exhibit clear differences from known crystal structures.

The use of dental sealants in adults: a long-neglected preventive measure.

The consensus among the general public appears to be that dental sealants are intended to be used primarily with children whose teeth are in the early developmental stage, yet little attention is given to the preventive long-term aspects when applying them to adult permanent dentition. This article explores the rationale and substantiates the use of dental sealants among the adult population in reducing occlusal pit-and-fissure caries while accentuating a beneficial oral health lifestyle.

Fast-scanning high-flux microprobe for biological X-ray fluorescence microscopy and microXAS.

There is a growing interest in the biomedical community in obtaining information concerning the distribution and local chemical environment of metals in tissues and cells. Recently, biological X-ray fluorescence microscopy (XFM) has emerged as the tool of choice to address these questions. A fast-scanning high-flux X-ray microprobe, built around a recently commissioned pair of 200 mm-long Rh-coated silicon Kirkpatrick-Baez mirrors, has been constructed at BioCAT beamline 18ID at the Advanced Photon Source. The new optical system delivers a flux of 1.3 x 10(12) photons s(-1) into a minimum focal spot size of approximately 3-5 microm FWHM. A set of Si drift detectors and bent Laue crystal analyzers may be used in combination with standard ionization chambers for X-ray fluorescence measurements. BioCAT's scanning software allows fast continuous scans to be performed while acquiring and storing full multichannel analyzer spectra per pixel on-the-fly with minimal overhead time (<20 ms per pixel). Together, the high-flux X-ray microbeam and the rapid-scanning capabilities of the BioCAT beamline allow the collection of XFM and micro X-ray absorption spectroscopy (microXAS) measurements from as many as 48 tissue sections per day. This paper reports the commissioning results of the new instrument with representative XFM and microXAS results from tissue samples.

Dynamic multi-phase partitioning of decamethylcyclopentasiloxane (D5) in river water.

The behaviour of decamethylcyclopentasiloxane (D5) in river water was evaluated by measuring concentration changes in open beakers. Effective values for the partition coefficient between organic carbon and water (K(OC)) were derived by least-squares optimisation of a dynamic model which accounted for partitioning between the sorbed and dissolved phases of D5, and for losses via volatilisation and hydrolysis. Partial mass transfer coefficients for volatilisation were derived from model fits to controls containing deionised water. Effective values of log (K(OC)) were between 5.8 and 6.33 (mean 6.16). These figures are higher than some other experimentally-derived values but much lower than those estimated from the octanol: water partition coefficient using single-parameter linear free energy relationships (LFERs). A poly-parameter LFER gave a predicted log (K(OC)) of 5.5. Differences in partitioning are believed to be due to the nature of the organic matter present. The new value for effective K(OC) was employed in a simple model of D5 behaviour in rivers to ascertain the extent to which a higher affinity for organic carbon would depress volatility. The results suggest that despite the revised K(OC) value, volatilisation of D5 remains a significant removal mechanism in surface waters.

Lack of a clinically relevant effect of an antacid on the pharmacokinetics of lersivirine.

Lersivirine (UK-453,061) is a next-generation nonnucleoside reverse transcriptase inhibitor that displays potent antiviral activity. Lersivirine solubility is pH dependent; therefore, the effect of coadministration of antacid on the pharmacokinetics of lersivirine in healthy subjects was investigated. The ratio of adjusted geometric means (750 mg lersivirine plus 20 ml Maalox Max/750 mg lersivirine alone) for the area under the curve from time zero extrapolated to infinite time (AUC(inf)) was 101.86%, showing that coadministration of an antacid had no effect on lersivirine exposure. Coadministration appeared to be safe and relatively well tolerated.

Reverse actin sliding triggers strong myosin binding that moves tropomyosin.

Actin/myosin interactions in vertebrate striated muscles are believed to be regulated by the "steric blocking" mechanism whereby the binding of calcium to the troponin complex allows tropomyosin (TM) to change position on actin, acting as a molecular switch that blocks or allows myosin heads to interact with actin. Movement of TM during activation is initiated by interaction of Ca(2+) with troponin, then completed by further displacement by strong binding cross-bridges. We report x-ray evidence that TM in insect flight muscle (IFM) moves in a manner consistent with the steric blocking mechanism. We find that both isometric contraction, at high [Ca(2+)], and stretch activation, at lower [Ca(2+)], develop similarly high x-ray intensities on the IFM fourth actin layer line because of TM movement, coinciding with x-ray signals of strong-binding cross-bridge attachment to helically favored "actin target zones." Vanadate (Vi), a phosphate analog that inhibits active cross-bridge cycling, abolishes all active force in IFM, allowing high [Ca(2+)] to elicit initial TM movement without cross-bridge attachment or other changes from relaxed structure. However, when stretched in high [Ca(2+)], Vi-"paralyzed" fibers produce force substantially above passive response at pCa approximately 9, concurrent with full conversion from resting to active x-ray pattern, including x-ray signals of cross-bridge strong-binding and TM movement. This argues that myosin heads can be recruited as strong-binding "brakes" by backward-sliding, calcium-activated thin filaments, and are as effective in moving TM as actively force-producing cross-bridges. Such recruitment of myosin as brakes may be the major mechanism resisting extension during lengthening contractions.

Presumed infective meningoencephalitis complicated by bilateral optic neuritis.

PURPOSE: To report a case of presumed infective meningoencephalitis complicated by bilateral optic neuritis. METHODS: Interventional case report. RESULTS: A 7-year-old Pakistani girl presented with fever and multiple right-sided focal seizures. Despite empirical treatment with antibiotic, anti-viral and anti-tuberculous therapy for presumed infective meningoencephalitis, she further deteriorated, developing altered consciousness, hemiplegia and severe, bilateral optic neuritis. No infectious agent could be identified. Following the addition of high dose systemic corticosteroid therapy, her optic nerve function in both eyes began to recover. At 3-month follow-up, the hemiplegia had completely resolved, and visual acuity was 6/6 bilaterally with normal pupillary responses. CONCLUSIONS: This case demonstrates that meningoencephalitis of presumed infective origin may be complicated by acute, severe, bilateral optic neuritis, the latter often mediating profound visual loss. In the setting of rapidly deteriorating vision, aggressive corticosteroid treatment, with antimicrobial cover, albeit unproven, remains the mainstay of treatment.

Peritoneal mucinous cystadenocarcinoma of probable urachal origin: a challenging diagnosis.

This report describes the case of a mucinous cystadenocarcinoma of probable urachal origin that presented with mass effect, precipitating deep venous thrombosis and pulmonary embolism. The patient presented with acute symptoms of leg swelling, pain and dyspnoea, and a vague awareness of lower abdominal distension. Computer tomography showed a cystic mass closely related to the anterior abdominal wall and the superior aspect of the bladder. A 1500 cm(3) cyst adherent to the dome of the urinary bladder was resected on laparotomy. Partial cystectomy was not carried out in the belief that the cyst represented a benign lesion. Subsequent imaging has shown cystic changes in the anterior bladder wall, and the patient has been referred for partial cystectomy.

Wide-angle X-ray solution scattering as a probe of ligand-induced conformational changes in proteins.

A chemical genetics approach to functional analysis of gene products utilizes high-throughput target-based screens of compound libraries to identify ligands that modulate the activity of proteins of interest. Candidates are further screened using functional assays designed specifically for the protein--and function--of interest, suffering from the need to customize the assay to each protein. An alternative strategy is to utilize a probe to detect the structural changes that usually accompany binding of a functional ligand. Wide-angle X-ray scattering from proteins provides a means to identify a broad range of ligand-induced changes in secondary, tertiary, and quaternary structure. The speed and accuracy of data acquisition, combined with the label-free targets and binding conditions achievable, indicate that WAXS is well suited as a moderate-throughput assay in the detection and analysis of protein-ligand interactions.

Characterisation of the dilute HCl extraction method for the identification of metal contamination in Antarctic marine sediments.

A regional survey of potential contaminants in marine or estuarine sediments is often one of the first steps in a post-disturbance environmental impact assessment. Of the many different chemical extraction or digestion procedures that have been proposed to quantify metal contamination, partial acid extractions are probably the best overall compromise between selectivity, sensitivity, precision, cost and expediency. The extent to which measured metal concentrations relate to the anthropogenic fraction that is bioavailable is contentious, but is one of the desired outcomes of an assessment or prediction of biological impact. As part of a regional survey of metal contamination associated with Australia's past waste management activities in Antarctica, we wanted to identify an acid type and extraction protocol that would allow a reasonable definition of the anthropogenic bioavailable fraction for a large number of samples. From a kinetic study of the 1 M HCl extraction of two Certified Reference Materials (MESS-2 and PACS-2) and two Antarctic marine sediments, we concluded that a 4 h extraction time allows the equilibrium dissolution of relatively labile metal contaminants, but does not favour the extraction of natural geogenic metals. In a regional survey of 88 marine samples from the Casey Station area of East Antarctica, the 4 h extraction procedure correlated best with biological data, and most clearly identified those sediments thought to be contaminated by runoff from abandoned waste disposal sites. Most importantly the 4 h extraction provided better definition of the low to moderately contaminated locations by picking up small differences in anthropogenic metal concentrations. For the purposes of inter-regional comparison, we recommend a 4 h 1 M HCl acid extraction as a standard method for assessing metal contamination in Antarctica.

The BioCAT undulator beamline 18ID: a facility for biological non-crystalline diffraction and X-ray absorption spectroscopy at the Advanced Photon Source.

The 18ID undulator beamline of the Biophysics Collaborative Access Team at the Advanced Photon Source, Argonne, IL, USA, is a high-performance instrument designed for, and dedicated to, the study of partially ordered and disordered biological materials using the techniques of small-angle X-ray scattering, fiber diffraction, and X-ray absorption spectroscopy. The beamline and associated instrumentation are described in detail and examples of the representative experimental results are presented.

Four pedigrees of the cation-leaky hereditary stomatocytosis class presenting with pseudohyperkalaemia. Novel profile of temperature dependence of Na+-K+ leak in a xerocytic form.

We report four pedigrees of the group of Na(+)-K(+)-leaky red cell disorders of the 'hereditary stomatocytosis' class. Each showed pseudohyperkalaemia because of temperature-dependent loss of K(+) from red cells on storage of whole blood at room temperature. All pedigrees showed an abnormality in the temperature dependence of the 'passive leak' of the membrane to K(+). Two pedigrees, both of which showed a compensated haemolytic state with dehydrated red cells and target cells on the blood film, showed a novel pattern, in which the profile was flat between 37 degrees C and about 32 degrees C then dropped as the temperature was reduced to zero. The third showed the 'shallow slope' profile, with stomatocytes on the blood film and very markedly abnormal intracellular Na(+) and K(+) levels. Minimal haemolysis was present. The fourth pedigree, of Asian origin, showed the shoulder pattern (minimum at 32 degrees C, maximum at 12 degrees C) with essentially normal haematology. Both of these latter two forms have previously been seen in other pedigrees. The first variant represents a novel kind of temperature dependence of the passive leak found in these pedigrees presenting with pseudohyperkalaemia.

Allogeneic bone marrow transplantation for severe post-splenectomy thrombophilic state in leaky red cell membrane haemolytic anaemia of the stomatocytosis class.

The tendency for thrombosis to occur if haemolysis persists after splenectomy is especially marked in "hereditary stomatocytosis", in which the red cell membrane "leaks" Na and K. A 21-year-old woman, who was splenectomized in childhood for a congenital haemolytic state, presented with major pulmonary embolism that recurred despite anticoagulation. Tests showed a significant cation leak with a "shallow-slope" abnormality in temperature dependence. Allogeneic bone marrow transplantation caused the thrombophilic state to cease and subsequently anticoagulation was stopped without recurrence of thromboembolism. However, she died 9 months after transplantation: iron overload, intensified by the transfusion demands of the transplant, was a major factor.