Euthanasia of piglets: gas or injection?

Methods for the humane killing of animals are watched critically by both the public and the veterinary community. Evaluation of such methods requires assessment of efficacy as well as emotional and ethical aspects. Rapidity of loss of consciousness is a crucial factor in such evaluations. In the present study, four methods for piglet euthanasia were compared with regard to presence of indicators of discomfort (pain, anxiety, stress) and rapidity of onset of death, defined as the absence of breathing, heart beats and reflexes, combined with isoelectricity of the electro-encephalogram (EEG). The study was performed on piglets, which had to be destroyed on account of preventive measures against swine fever. The following methods were applied: CO2 98%, CO2/O2 65/35%, T61 and pentobarbital (Euthesate) injected intracardially. Intracardial injections of T61 and pentobarbital provide fast unconsciousness and death with minimal discomfort to the animal.     

Differences in the level of expression of class I major histocompatibility complex proteins on thymic epithelial and dendritic cells influence the decision of immature thymocytes between positive and negative selection

Both positive and negative selection of immature T cells rely on engagement of their antigen-specific receptors (TCR) by peptide in association with proteins encoded in the major histocompatibility complex (MHC) protein. The decision made between these two outcomes seems to be determined by the number of TCR engaged by peptide-MHC complexes. It has been unclear how such a mechanism can be reconciled with evidence that positive and negative selection occur in different thymic compartments and are mediated by different antigen-presenting cells (APCs). In this study we demonstrate that the level of class I MHC protein is 10-fold higher on thymic dendritic cells, which mediate the negative selection of immature T cells, than on thymic epithelial cells, which mediate for positive selection. We also demonstrate that as little as a 3-fold increase in the level of a particular cognate peptide-MHC ligand is sufficient to result in negative rather than positive selection. The results suggest that quantitative differences in the level of expression of class I MHC proteins on thymic epithelial and dendritic cells contribute to the opposing roles these cells play in forming the repertoire of mature class I MHC restricted (CD8+) T cells.     

The membrane topology of the amino-terminal domain of the red cell calcium pump

A systematic study of the membrane-associated regions in the plasma membrane Ca2+ pump of erythrocytes has been performed by hydrophobic photolabeling. Purified Ca2+ pump was labeled with 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)-diazirine ([125I]TID), a generic photoactivatable hydrophobic probe. These results were compared with the enzyme labeled with a strictly membrane-bound probe, [3H]bis-phosphatidylethanolamine (trifluoromethyl) phenyldiazirine. A significant light-dependent labeling of an M(r) 135,000-140,000 peptide, corresponding to the full Ca2+ pump, was observed with both probes. After proteolysis of the pump labeled with each probe and isolation of fragments by SDS-PAGE, a common pattern of labeled peptides was observed. Similarly, labeling of the Ca2+ pump with [125I]TID, either in isolated red blood cell membranes or after the enzyme was purified, yields a similar pattern of labeled peptides. Taken together, these results validate the use of either probe to study the lipid interface of the membrane-embedded region of this protein, and sustain the notion that the conformation of the pump is maintained throughout the procedures of solubilization, affinity purification, and reconstitution into proteoliposomes. In this work, we put special emphasis on a detailed analysis of the N-terminal domain of the Ca2+ pump. A labeled peptide of M(r) 40,000 belonging to this region was purified and further digested with V8 protease. The specific incorporation of [125I]TID to proteolytic fragments pertaining to the amino-terminal region indicates the existence of two transmembrane stretches in this domain. A theoretical analysis based on the amino acid sequence 1-322 predicts two segments with high probability of membrane insertion, in agreement with the experimental data. Each segment shows a periodicity pattern of hydrophobicity and variability compatible with alpha-helical structure. These results strongly suggest the existence of a transmembrane helical hairpin motif near the N-terminus of the Ca2+ pump.     

Association of benign prostatic hyperplasia with male pattern baldness

OBJECTIVE: To determine whether crude extracts of ginseng saponin (GCS), containing the active ingredients from Panax ginseng and used as an aphrodisiac in oriental countries, relax corpus cavernosal smooth muscle in the rabbit. MATERIALS AND METHODS: Corpus cavernosal strips were prepared from rabbit penises. Isometric tension changes, recorded with a pressure transducer, in response to various drugs and electrical stimulation were assessed in an organ chamber, after active muscle tone had been induced by 10 micromol/L phenylephrine. RESULTS: GCS (0.2-8.0 mg) relaxed the smooth muscle of rabbit corpus cavernosum (SMRCC) pre-contracted with phenylephrine in a dose-dependent manner. GCS at 0.75 mg significantly enhanced the relaxation of SMRCC induced by electrical field stimulation. The relaxation induced by 0.2-8.0 mg GCS was significantly attenuated by atropine (1 micromol/L), methylene blue (100 micromol/L) and N-omega-nitro-L-arginine methyl ester (L-NAME, 10 micromol/L). However, there was no significant difference in the attenuation of GCS-induced relaxation of SMRCC by adding vasoactive intestinal peptide antagonists or indomethacin. In addition, the decreasing rate of GCS-induced relaxation of SMRCC by methylene blue and L-NAME was greater than that by atropine. L-arginine (10 mmol/L) reversed the inhibitory effect induced by L-NAME (1 mmol/L) on the attenuation of GCS-induced relaxation. CONCLUSIONS: These data suggest that GCS, as a nitric oxide donor, induces the relaxation of SMRCC through the L-arginine/nitric oxide pathway. For the clinical application of ginseng saponin, further studies are required to clarify the active subfraction(s) of GCS.     

Induction of species-specific host accommodation in the hamster-to-rat xenotransplantation model

The combination of two immunosuppressants, leflunomide and cyclosporin A (CsA), completely inhibits immune xenoreactions in the hamster-to-Lewis rat xenotransplantation model. In addition, the control of acute xenograft rejection with this combination of immunosuppressants subdues early T-independent xenoreactivity and uncovers a late immune response that can be controlled by CsA alone. We attribute this acquired responsiveness to CsA to a modification in the recipient's humoral response to the xenograft, and refer to this change as host accommodation. Host accommodation can be induced in Lewis rats receiving hamster hearts by the combination of leflunomide and CsA. A 7-day treatment with leflunomide and CsA was able to convert xenoreactivity from one that was resistant to CsA treatment into one that was controlled by CsA. The presence of the hamster xenograft was critical for the induction of host accommodation since the immunosuppressive regimen, either alone or in combination with a transfusion with donor-specific spleen cells, was unable to modify the anti-hamster reactivity in Lewis rats. When accommodation was induced in the presence of hamster hearts, these accommodated rats were able to acutely reject third-party mouse hearts while under CsA therapy, thus indicating that the host accommodation is species specific. Finally, we demonstrate that host accommodation is associated with a loss in the ability to produce species-specific, T-independent xenoantibodies. These novel observations suggest that xenoreactive T-independent humoral responses can be deleted selectively without significant loss of other innate, Ag-specific T-independent humoral responses.     

Inhibition of N-glycan processing in B16 melanoma cells results in inactivation of tyrosinase but does not prevent its transport to the melanosome

Tyrosinase is the key enzyme in melanin biosynthesis, catalyzing multiple steps in this pathway. The mature glycoprotein is transported from the Golgi to the melanosome where melanin biosynthesis occurs. In this study, we have investigated the effects of inhibitors of N-glycan processing on the synthesis, transport, and catalytic activity of tyrosinase. When B16 mouse melanoma cells were cultured in the presence of N-butyldeoxynojirimycin, an inhibitor of the endoplasmic reticulum-processing enzymes alpha-glucosidases I and II, the enzyme was synthesized and transported to the melanosome but almost completely lacked catalytic activity. The cells contained only 2% of the melanin found in untreated cells. Structural analysis of the N-glycans from N-butyldeoxynojirimycin-treated B16 cells demonstrated that three oligosaccharide structures (Glc3Man7-9) predominated. Removal of the glucose residues with alpha-glucosidases I and II failed to restore enzymatic activity, suggesting that the glucosylated N-glycans do not sterically interfere with the enzyme's active sites. The mannosidase inhibitor deoxymannojirimycin had no effect on catalytic activity suggesting that the retention of glucosylated N-glycans results in the inactivation of this enzyme. The retention of glucosylated N-glycans does not therefore result in misfolding and degradation of the glycoprotein, as the enzyme is transported to the melanosome, but may cause conformational changes in its catalytic domains.     

Pregnancy achieved by intracytoplasmic sperm injection using cryopreserved vasal-epididymal sperm from a man with spinal cord injury

We herein describe a male patient who died at 37 years of age, after having suffered from a slowly progressive syndrome of chronic sensory motor neuropathy, deafness, retinitis pigmentosa and ataxia. The neuropathological study showed symmetric areas of necrosis and demyelination affecting the cerebellum and brainstem. The type of lesion was consistent with the characteristics of Leigh Syndrome. On the basis of the histology of the lesions, we believe that they appeared only a few months before the death of the patient. We underline the atypical clinical picture and suggest that, in certain cases, brain MRI may not be a reliable diagnostic tool.     

Semistructural allografting in bone defects after curettage

Amongst the focal and multifocal neuropathies that are associated with diabetes mellitus one of the most common is a proximal predominantly motor lower limb neuropathy. Recent evidence has indicated that, at least in a proportion of cases, this may have an inflammatory basis. We have examined a consecutive series of 15 cases of proximal diabetic neuropathy (diabetic amyotrophy). These were characterized by proximal pain and asymmetric proximal or generalized lower limb muscle weakness, associated in some cases with radicular sensory involvement. Two-thirds of the patients had an accompanying distal symmetric sensory polyneuropathy. Biopsy of the intermediate cutaneous nerve of the thigh, a sensory branch of the femoral nerve, showed epineurial microvasculitis in 3 patients and nonvasculitic epineurial inflammatory infiltrates in another case. In a further case, microvasculitis was found in both in the sural nerve and a quadriceps muscle biopsy specimen. The detection of inflammatory changes appeared to be correlated with the occurrence of sensory radicular involvement. Whether similar changes are present in muscle nerves in this predominantly motor syndrome requires further study. Nevertheless, the present observations confirm the view that secondary vasculitic or other inflammatory reactions may contribute to some forms of diabetic neuropathy.     

Synthesis of 9-deoxo-4'-deoxy-6,9-epoxyerythromycin derivatives: novel and acid-stable motilides

In our quest toward the discovery of highly potent and acid-stable motilides, novel 4"-deoxy derivatives of 9-deoxo-6, 9-epoxyerythromycin were designed, synthesized, and evaluated for their gastrointestinal prokinetic activities. These compounds, in their 9R configuration, were more potent than their 6,9-enol ether homologues in inducing well-coordinated smooth muscle contractions in an in vitro rabbit duodenal assay: e.g., (9R), (8S)-9-deoxo-4"-deoxy-3'-N-desmethyl-3'-N-ethyl-6, 9-epoxyerythromycin A (10) and (9R), (8S)-9-deoxo-4"-deoxy-3'-N-desmethyl-3'-N-ethanol-6, 9-epoxyerythromycin A (15) had a pED50 of 8.54 and 8.11 compared to a pED50 of 7.22 for compound 2 (ABT-229). Reduction of the 6,9-enol ether, which was aimed at improving the acid stability, afforded the most stable motilides to date with t1/2 of 5.5 h for 10 and 15. Compounds 10 and 15 bind specifically to rabbit antral smooth muscle motilin receptors with pIC50 values of 8.52 and 8.70.