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91.
Massive scrotal edema is an unreported complication of abdominoplasty. This patient's postoperative decompensation of medial thigh and scrotal lymphatic return may well have been due to an occult lymphedema tarda or previously compromised lymphatics from the fibrosis of venous stasis disease and obesity. 相似文献
92.
Pharmacological investigation of the mechanisms of platelet-activating factor induced mortality in the mouse 总被引:4,自引:0,他引:4
Although the platelets of the mouse are refractory to the direct effects of platelet-activating-factor (PAF), tail vein injection of 10-150 micrograms/kg PAF produces lethal anaphylactic shock. Sensitivity varies with strain and source: Swiss Webster mice show a range of sensitivity and DBA/2 (complement C5-deficient) mice are very resistant. At lethal doses of PAF, animals show labored respiration and general depression; death occurs within 15-45 min. Dexamethasone administered at least 1.5 hr prior consistently protects, whereas the cyclooxygenase inhibitors do not. Antihistamines, adrenergic antagonists, and methysergide have no effect, but cyproheptadine is partially protective at near lethal doses. Calcium entry blockers and calcium chelators, tetracycline and chlortetracycline are partially protective at very high doses consistent with non-specific effects on calcium dependent processes. The arachidonic acid lipoxygenase inhibitors BW755c, phenidone, nordihydroguaiaretic acid and diphenyldisulfide provide nearly complete protection after oral administration of 50-200 mg/kg. Phosphodiesterase inhibitors and dapsone are also effective orally. The leukotriene antagonist FPL55712 administered intraperitoneally (10 mg/kg) 5 min. prior to PAF challenge provides almost complete protection. PAF-induced mortality in the mouse represents a small animal model of systemic anaphylaxis particularly useful for the systemic testing of arachidonic acid lipoxygenase inhibitors and leukotriene antagonists. 相似文献
93.
[C-lignin]lignocellulose was solubilized by alkaline heat treatment and separated into different molecular size fractions for use as the sole source of carbon in anaerobic enrichment cultures. This study is aimed at determining the fate of low-molecular-weight, polyaromatic lignin derivatives during anaerobic degradation. Gel permeation chromatography was used to preparatively separate the original C-lignin substrate into three component molecular size fractions, each of which was then fed to separate enrichment cultures. Biodegradability was assessed by monitoring total carbon dioxide and methane production, evolution of labeled gases, loss of C-activity from solution, and changes in gel permeation chromatographic elution patterns. Results indicated that the smaller the size of the molecular weight fraction, the more extensive the degradation to gaseous end products. In addition, up to 30% of the entire soluble lignin-derived carbon was anaerobically mineralized to carbon dioxide and methane. 相似文献
94.
The thiol groups of mouse immunoglobulin A. Incomplete formation of the C alpha 1-domain disulphide bridge. 下载免费PDF全文
The BALB/c IgA (immunoglobulin A) myeloma protein M167 contained on average 5.7 free SH groups per IgA dimer. These groups were preponderantly on the heavy chains and comprised two distinct populations: 3.3 exposed SH groups per dimer in the Fc region, and 2.4 buried SH groups per dimer in the Fd region, detectable o only after denaturation. To locate the cysteine residues involved, labelled peptides were purified from thermolysin digests of radioalkylated IgA by high-performance liquid chromatography. From the amino acid compositions of the peptides, the exposed thiol groups were assigned to Cys-307 in the C alpha 2 domain, which thus existed in the reduced form to an extent exceeding 80%. This residue may allow attachment of secretory component to dimer IgA in the mouse to proceed via thiol-disulphide exchange. The buried thiol groups were assigned to Cys-150 and Cys-208, in the C alpha 1 domain, each being in the reduced form to the extent of approx. 30%. This pair of residues would normally give rise to the characteristic intradomain disulphide bridge. It appears that disulphide formation is not a crucial event during folding of the C alpha 1 domain in IgA biosynthesis. The sequence in the region 140-151 was re-investigated, and residue 142 was shown to be serine, not cysteine, helping explain the lack of heavy-chain-light chain bonding in BALB/c mouse IgA. A disulphide-bond model for mouse IgA is proposed on the basis of these assignments and other features of the mouse alpha-chain sequence. 相似文献
95.
Proteolytic cleavage of [3H]nitrobenzylthioinosine-labelled nucleoside transporter in human erythrocytes. 下载免费PDF全文
The transmembrane topology of the nucleoside transporter of human erythrocytes, which had been covalently photolabelled with [3H]nitrobenzylthioinosine, was investigated by monitoring the effect of proteinases applied to intact erythrocytes and unsealed membrane preparations. Treatment of unsealed membranes with low concentrations of trypsin and chymotrypsin at 1 degree C cleaved the nucleoside transporter, a band 4.5 polypeptide, apparent Mr 66 000-45 000, to yield two radioactive fragments with apparent Mr 38 000 and 23 000. The fragment of Mr 38 000, in contrast to the Mr 23 000 fragment, migrated as a broad peak (apparent Mr 45 000-31 000) suggesting that carbohydrate was probably attached to this fragment. Similar treatment of intact cells under iso-osmotic saline conditions at 1 degree C had no effect on the apparent Mr of the [3H]nitrobenzylthioinosine-labelled band 4.5, suggesting that at least one of the trypsin cleavage sites resulting in the apparent Mr fragments of 38 000 and 23 000 is located at the cytoplasmic surface. However, at low ionic strengths the extracellular region of the nucleoside transporter is susceptible to trypsin proteolysis, indicating that the transporter is a transmembrane protein. In contrast, the extracellular region of the [3H]cytochalasin B-labelled glucose carrier, another band 4.5 polypeptide, was resistant to trypsin digestion. Proteolysis of the glucose transporter at the cytoplasmic surface generated a radiolabelled fragment of Mr 19 000 which was distinct from the Mr 23 000 fragment radiolabelled with [3H]nitrobenzylthioinosine. The affinity for the reversible binding of [3H]cytochalasin B and [3H]nitrobenzylthioinosine to the glucose and nucleoside transporters, respectively, was lowered 2-3-fold following trypsin treatment of unsealed membranes, but the maximum number of inhibitor binding sites was unaffected despite the cleavage of band 4.5 to lower-Mr fragments. 相似文献
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Localization and characterization of members of a family of repetitive sequences in the goat beta globin locus. 总被引:3,自引:3,他引:0 下载免费PDF全文
We have characterized a family of repetitive DNA elements in the beta-globin locus of the goat. These sequences are structurally analogous to the Alu families of repeats of other mammals. Repetitive elements are located both in the intervening sequences and in the intergenic regions of the goat beta-globin locus. Nucleotide sequence analysis of five repetitive elements located within the large intervening sequence of the beta-like globin genes, and four repeats located 5' to the major developmentally regulated beta-globin genes has resulted in the definition of a consensus sequence for this family of repeats. 相似文献