The effect of phosphate on the binuclear iron center of pink (reduced) uteroferrin was examined by magnetic resonance and optical spectroscopy. The purple (oxidized) protein, which contains 1 mol of tightly bound phosphate per mol of enzyme at isolation, does not give rise to a 31P NMR signal. Phosphate binding to phosphate-stripped pink uteroferrin is indistinguishable from that in the native purple phosphoprotein. As measured by EPR and optical spectroscopy, the rate of reaction between phosphate and pink uteroferrin is pH-dependent, decreasing as the pH increases. Phosphate is capable of binding to the reduced protein between pH 3 and 7.8, resulting in formation of the purple uteroferrin-phosphate complex. Evans susceptibility measurements at pH 4.9 indicate that the EPR silent species with a maximum absorption at 535 nm, generated upon phosphate addition to pink uteroferrin, is diamagnetic. Moreover, phosphate causes disappearance of the hyperfine-shifted resonances in the 1H NMR spectra of the reduced protein. We therefore have not been able to identify the paramagnetic "purple reduced enzyme-phosphate complex" reported by Pyrz et al. (Pyrz, J. W., Sage, J. T., Debrunner, P. G., and Que, Jr., L. (1986) J. Biol Chem. 261, 11015-11020) using Mossbauer spectroscopy and dithionite-reduced 57Fe-reconstituted uteroferrin. Our present data with native unmodified enzyme are in accord with our earlier results (Antanaitis, B. C., and Aisen, P. (1985) J. Biol. Chem. 260, 751-756) and with the results of Burman et al. (Burman, S., Davis, J. C., Weber, M. J., and Averill, B. A. (1986) Biochem. Biophys. Res. Commun. 136, 490-497) on bovine spleen phosphatase, suggesting that phosphate binding to reduced protein rapidly induces oxidation of the binuclear iron center.

Acid Phosphatase↗

PubMed1987

Thermal and solvent stability of proteoglycan aggregates by quasielastic laser light-scattering.

The dissociation behavior of several species of proteoglycan aggregates (PGA) has been studied quantitatively by monitoring the changes in particle size by dynamic laser light-scattering. Firstly, studies of the thermal dissociation of reconstituted PGA from bovine nasal septum and bovine fetal epiphysus are described. The effect of link protein in stabilizing reconstituted PGA against changes in temperature has been demonstrated. It was also confirmed that, upon prolonged heating at 70 degrees, the dissociation of link-containing, reconstituted PGA is effectively irreversible. Secondly, the dissociation characteristics of native PGA isolated from chick chondrocyte and rat chondrosarcoma cell-cultures were investigated in aqueous solvents containing increasing concentrations of guanidine hydrochloride. It was found that the more densely packed, native, aggregate structure has a higher susceptibility to thermal disruption than the reconstituted, link-containing material. Considerable loss of subunits from the native aggregates occurs at temperature where the link protein retains its activity. The dissociation of native PGA is irreversible, in the sense that reconstituted PGA always exhibits smaller sizes than the native PGA, reflecting a smaller degree of aggregation of the subunits.

Animals↗

PubMed1987

Structure determination of a new fluorescent tricyclic nucleoside from archaebacterial tRNA.

A highly fluorescent nucleoside was detected in enzymatic digests of the extremely thermophilic archaebacterium Sulfolobus solfataricus by combined liquid chromatography-mass spectrometry (LC/MS). Following isolation, the structure was determined primarily by mass spectrometry, to be 3-(beta-D-ribofuranosyl)-4,9-dihydro-4,6,7-trimethyl-9-oxoimidazo[ 1, 2-a]purine (mimG), a new derivative of the Y (wye) nucleoside. The structural assignment was verified by comparison of the base released by acid hydrolysis with the corresponding synthetic base, using mass spectrometry, chromatography, and UV absorption and fluorescence properties. Nucleoside mimG was also detected by LC/MS in hydrolysates of the thermophiles Thermoproteus neutrophilus and Pyrodictium occultum. These results constitute the first finding of a member of the hypermodified Y family of nucleosides in archaebacteria.

Archaea↗

PubMed1987

Acute superior mesenteric ischaemia.

A review of case records and post-mortem reports from Glasgow Royal Infirmary over the past 12 years identified 102 patients with acute superior mesenteric ischaemia, 53 (52 per cent) of whom were first diagnosed at post mortem. Overall mortality was 92 per cent and mortality in the 49 patients diagnosed in life was 84 per cent. Fourteen patients (14 per cent) underwent exploratory laparotomy only with no survivors, 26 (25 per cent) had bowel resection alone with 7 surviving, and 9 (9 per cent) had a revascularization procedure, 5 requiring additional bowel resection, with only one surviving. Survivors were usually younger, had a shorter history and less extensive bowel infarction. Improvements in intensive care and nutritional support with the greater use of revascularization procedures in the past 6 years have barely influenced mortality. Delays in diagnosis and treatment contribute to the poor results. Earlier diagnosis might be aided by measuring serum inorganic phosphate and, coupled with the more widespread use of emergency angiography and revascularization procedures, holds out the best hope for future improvement.

Acute Disease↗

PubMed1987

The distribution of transferrin, group-specific component and phosphoglucomutase-1 subtypes among the Lepchas of Darjeeling, eastern India.

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Alleles↗

PubMed1987

Tuberculous peritonitis in children.

Five cases of tuberculous peritonitis are presented with clinical and radiological features. The diagnosis was based on clinical and radiological findings. Peritoneoscopy and laparatomy was not performed in any of the cases. All the patients responded well to the anti-tubercular therapy.

Child↗

PubMed1987

Perigraft seroma: clinical, histologic, and serologic correlates.

A 14 year retrospective study of perigraft seroma, defined as an enlarging sterile fluid collection at the site of a prosthetic graft, revealed well-documented cases in 5 of 118 extraanatomical bypasses (4.2 percent), 3 of 248 aortic reconstructive procedures (1.2 percent), and 1 of 395 femoropopliteal bypasses (0.3 percent). These nine cases involved four polytetrafluoroethylene and five Dacron grafts. There were five graft thromboses, one instance of limb loss, two graft infections, two deaths, and 13 separate surgical procedures related to the perigraft seroma. Histologic studies revealed a fibrous pseudomembrane lining the perigraft seroma wall and immature fibroblasts lining the graft. Sera from three patients with perigraft seroma, five patients with well-incorporated prosthetic grafts, and three healthy volunteer subjects were tested for in vitro evidence of fibroblast inhibition against fibroblast tissue cultures derived from the pseudomembrane of a perigraft seroma. Control fetal calf serum, sera from all three healthy subjects, and sera from all five patients with well-incorporated grafts allowed fibroblast proliferation. In contrast, sera from all three patients with perigraft seroma inhibited fibroblast growth. Furthermore, sera collected 1, 2, and 3 months after graft removal from one patient and serum collected 3 months after spontaneous resolution of a perigraft seroma from another patient failed to inhibit fibroblasts. We have concluded that patients with perigraft seroma have a high rate of graft and limb loss and require multiple reoperations. The pathogenesis of perigraft seroma appears to involve a humoral fibroblast inhibitor which prevents maturation and proliferation of perigraft fibroblasts, leading to poor graft incorporation. The decrease of inhibition below detectable levels after graft removal or spontaneous resolution of the perigraft seroma suggests that the graft may induce host production of the inhibitor. Effective therapy of perigraft seroma may include fibroblast modulation, removal of the inciting graft, or both.

Blood Vessel Prosthesis↗

PubMed1987

Fertility in cryptorchidism: improved timing of fixation and treatment in an experimental model.

Modifications were made in an experimental model in the rat to make it more analogous to human cryptorchidism and more useful in evaluating treatment. The age of experimental bilateral cryptorchidism was changed from 3 days to 11 days. Neither group was able to father offspring. The age at orchiopexy also was modified from the range of 21 to 28 days to exactly 21 days. The ability to father offspring improved significantly (72 versus 30 per cent) and it was not significantly different from previously reported sham operated rats (84 per cent). The current experimental model demonstrates that early surgical treatment can restore fertility to mechanically cryptorchid animals. The model can be used to evaluate the effects of varying types and timing of treatment.

Age Factors↗