Prolapsus vaginae in the IIIVO/JU rabbit

In a specified pathogen free (SPF) breeding colony of IIIVO/JU rabbits 8 cases of prolapsus vaginae occurred in 5 years. Clinically the animals were in shock. Haematocrits ranged from 9 to 15%. The prolapses started from the submucosal layer of the proximal part of the vestibulum vaginae. The prolapsed tissue consisted of over-expanded blood-sinuses. Between the sinuses signs of an inflammatory reaction were present. All 8 animals were in a period of increasing sexual activity when the prolapse developed. The 8 rabbits were closely related, indicating a possible hereditary defect.     

Activation of the non-electrochromic component in the 518 nm absorbance change by photosystem I

The flash-induced absorbance change measured at 518 nm (P515) in intact chloroplasts consists of at least 4 kinetically different components. Here the non-electrochromic component, either called phase d or reaction 3, is studied in some detail. The effect of DCMU, DQH₂ and DBMIB on the amplitude of reaction 3 and the turnover of cytochrome f and P700 have been monitored, suggesting an involvement of photosystem 1 in the activation of the non-electrochromic absorbance change. This is confirmed by the parallel oscillation pattern found in P700 rereduction and the amplitude of reaction 3.     

Isolation and structure elucidation of a novel adipokinetic hormone (Lom-AKH-III) from the glandular lobes of the corpus cardiacum of the migratory locust, Locusta migratoria

A new adipokinetic hormone (named Lom-AKH-III) was isolated from the glandular lobes of the corpora cardiaca of Locusta migratoria. At the N-terminus it is blocked by a 5-oxoproline (pyroglutamic acid) residue (less than Glu). After enzymatic deblocking, the amino acid sequence of the N-terminus was partly established by automatic Edman degradation to be [less than Glu]-Leu-Asn-Phe-Thr-Pro-. Fast-atom-bombardment spectrometry (FAB-MS) revealed that the new hormone is an octapeptide, which is amidated at the C-terminus, and has a relative molecular mass of 1072. Based on the FAB-MS data the complete sequence is less than Glu-Leu-Asn-Phe-Thr-Pro-Trp-Trp-NH2, which was confirmed by chemical synthesis. All characteristics from HPLC, FAB-MS and biological activity of the natural hormone and the synthetic peptide appeared to be identical. Although the structure of this new hormone resembles that of Lom-AKH-I (less than Glu-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2), its amino acid sequence points to a completely different route for its biosynthesis, involving a third prohormone. High-[K+]-containing media can cause release of all three adipokinetic hormones in vitro. Interestingly, the new hormone is absent in another locust species. Schistocerca gregaria. Based on in vitro biosynthesis experiments the turnover for this hormone is very high, suggesting an important physiological function. Locusta migratoria is the first insect species in which three different adipokinetic hormones have been demonstrated.     

Equilibrium-Phase High Spatial Resolution Contrast-Enhanced MR Angiography at 1.5T in Preoperative Imaging for Perforator Flap Breast Reconstruction

Objectives

The aim was (i) to evaluate the accuracy of equilibrium-phase high spatial resolution (EP) contrast-enhanced magnetic resonance angiography (CE-MRA) at 1.5T using a blood pool contrast agent for the preoperative evaluation of deep inferior epigastric artery perforator branches (DIEP), and (ii) to compare image quality with conventional first-pass CE-MRA.

Methods

Twenty-three consecutive patients were included. All patients underwent preoperative CE-MRA to determine quality and location of DIEP. First-pass imaging after a single bolus injection of 10 mL gadofosveset trisodium was followed by EP imaging. MRA data were compared to intra-operative findings, which served as the reference standard.

Results

There was 100% agreement between EP CE-MRA and surgical findings in identifying the single best perforator branch. All EP acquisitions were of diagnostic quality, whereas in 10 patients the quality of the first-pass acquisition was qualified as non-diagnostic. Both signal- and contrast-to-noise ratios were significantly higher for EP imaging in comparison with first-pass acquisitions (p<0.01).

Conclusions

EP CE-MRA of DIEP in the preoperative evaluation of patients undergoing a breast reconstruction procedure is highly accurate in identifying the single best perforator branch at 1.5Tesla (T). Besides accuracy, image quality of EP imaging proved superior to conventional first-pass CE-MRA.     

The two biosynthetic routes leading to phosphatidylcholine in yeast produce different sets of molecular species. Evidence for lipid remodeling

Phosphatidylcholine (PC), a major lipid class in the membranes of eukaryotes, is synthesized either via the triple methylation of phosphatidylethanolamine (PE) or via the CDP-choline route. To investigate whether the two biosynthetic routes contribute differently to the steady-state profile of PC species, i.e., PC molecules with specific acyl chain compositions, the pools of newly synthesized PC species were monitored by labeling Saccharomyces cerevisiae with deuterated precursors of the two routes, (methyl-D3)-methionine and (D13)-choline, respectively. Electrospray ionization tandem mass spectrometry (ESI-MS/MS) revealed that the two PC biosynthetic pathways yield different sets of PC species, with the CDP-choline route contributing most to the molecular diversity. Moreover, yeast was shown to be capable of remodeling PC by acyl chain exchange at the sn-1 position of the glycerol backbone. Remodeling was found to be required to generate the steady-state species distribution of PC. This is the first study demonstrating a functional difference between the two biosynthetic routes in yeast.     

Real-time monitoring of enzymatic DNA hydrolysis by electrospray ionization mass spectrometry

A fast and direct method for the monitoring of enzymatic DNA hydrolysis was developed using electrospray ionization mass spectrometry. We incorporated the use of a robotic chip-based electrospray ionization source for increased reproducibility and throughput. The mass spectrometry method allows the detection of DNA fragments and intact non-covalent protein–DNA complexes in a single experiment. We used the method to monitor in real-time single-stranded (ss) DNA hydrolysis by colicin E9 DNase and to characterize transient non-covalent E9 DNase–DNA complexes present during the hydrolysis reaction. The mass spectra showed that E9 DNase interacts with ssDNA in the absence of a divalent metal ion, but is strictly dependent on Ni²⁺ or Co²⁺ for ssDNA hydrolysis. We demonstrated that the sequence selectivity of E9 DNase is dependent on the ratio protein:ssDNA or the ssDNA concentration and that only 3′-hydroxy and 5′-phosphate termini are produced. It was also shown that the homologous E7 DNase is reactive with Zn²⁺ as transition metal ion and that this DNase displays a different sequence selectivity. The method described is of general use to analyze the reactivity and specificity of nucleases.     

Endogenous phosphatidylcholine and a long spacer ligand stabilize the lipid-binding groove of CD1b

CD1 proteins present lipid antigens to T cells. The antigens are acquired in the endosomal compartments. This raises the question of how the large hydrophobic CD1 pockets are preserved between the moment of biosynthesis in the endoplasmic reticulum and arrival to the endosomes. To address this issue, the natural ligands associated with a soluble form of human CD1b have been investigated. Using isoelectric focusing, native mass spectrometry and resolving the crystal structure at 1.8 A resolution, we found that human CD1b is simultaneously associated with endogenous phosphatidylcholine (PC) and a 41-44 carbon atoms-long spacer molecule. The two lipids appear to work in concert to stabilize the CD1b groove, their combined size slightly exceeding the maximal groove capacity. We propose that the spacer serves to prevent binding of ligands with long lipid tails, whereas short-chain lipids might still displace the PC, which is exposed at the groove entrance. The data presented herein explain how the CD1b groove is preserved, and provide a rationale for the in vivo antigen-binding properties of CD1b.     

MRI of arterial flow reserve in patients with intermittent claudication: feasibility and initial experience

Objectives

The aim of this work was to develop a MRI method to determine arterial flow reserve in patients with intermittent claudication and to investigate whether this method can discriminate between patients and healthy control subjects.

Methods

Ten consecutive patients with intermittent claudication and 10 healthy control subjects were included. All subjects underwent vector cardiography triggered quantitative 2D cine MR phase-contrast imaging to obtain flow waveforms of the popliteal artery at rest and during reactive hyperemia. Resting flow, maximum hyperemic flow and absolute flow reserve were determined and compared between the two groups by two independent MRI readers. Also, interreader reproducibility of flow measures was reported.

Results

Resting flow was lower in patients compared to controls (4.9±1.6 and 11.1±3.2 mL/s in patients and controls, respectively (p<0.01)). Maximum hyperemic flow was 7.3±2.9 and 16.4±3.2 mL/s (p<0.01) and the absolute flow reserve was 2.4±1.6 and 5.3±1.3 mL/s (p<0.01), respectively in patients and controls. The interreader coefficient of variation was below 10% for all measures in both patients and controls.

Conclusions

Quantitative 2D MR cine phase-contrast imaging is a promising method to determine flow reserve measures in patients with peripheral arterial disease and can be helpful to discriminate patients with intermittent claudication from healthy controls.