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Biomedical subjects

D Saunders

Publications and source records attributed to D Saunders.

At least 55 records · Page 3Linked to original sources
PubMed1995

The crystal structure of the catalytic domain of human urokinase-type plasminogen activator.

BACKGROUND: Urokinase-type plasminogen activator (u-PA) promotes fibrinolysis by catalyzing the conversion of plasminogen to the active protease plasmin via the cleavage of a peptide bond. When localized to the external cell surface it contributes to tissue remodelling and cellular migration; inhibition of its activity impedes the spread of cancer. u-PA has three domains: an N-terminal receptor-binding growth factor domain, a central kringle domain and a C-terminal catalytic protease domain. The biological roles of the fibrinolytic enzymes render them therapeutic targets, however, until now no structure of the protease domain has been available. Solution of the structure of the u-PA serine protease was undertaken to provide such data. RESULTS: The crystal structure of the catalytic domain of recombinant, non-glycosylated human u-PA, complexed with the inhibitor Glu-Gly-Arg chloromethyl ketone (EGRcmk), has been determined at a nominal resolution of 2.5 A and refined to a crystallographic R-factor of 22.4% on all data (20.4% on data > 3 sigma). The enzyme has the expected topology of a trypsin-like serine protease. CONCLUSIONS: The enzyme has an S1 specificity pocket similar to that of trypsin, a restricted, less accessible, hydrophobic S2 pocket and a solvent-accessible S3 pocket which is capable of accommodating a wide range of residues. The EGRcmk inhibitor binds covalently at the active site to form a tetrahedral hemiketal structure. Although the overall structure is similar to that of homologous serine proteases, at six positions insertions of extra residues in loop regions create unique surface areas. One of these loop regions is highly mobile despite being anchored by the disulphide bridge which is characteristic of a small subset of serine proteases namely tissuetype plasminogen activator, Factor XII and Complement Factor I.

Amino Acid Sequence↗
PubMed1995

Comparative study of laparoscopic oophorectomy.

STUDY OBJECTIVE: To determine the differences between laparoscopic oophorectomies and oophorectomies performed by laparotomy with respect to total hospital cost, length of hospital stay, and operative time. DESIGN: A prospective analysis of all women who underwent one of these procedures from January 1, 1992, to December 31, 1992. SETTING: A university-affiliated hospital. PATIENTS: Fifty-seven women requiring surgery for the management of pelvic pain, adnexal masses, or endometriosis. INTERVENTIONS: Twenty-six women underwent laparoscopic surgery and 31 had laparotomy. MEASUREMENTS AND MAIN RESULTS: The results for laparoscopy and laparotomy, respectively, were as follows: mean hospital cost $6139 versus $7053 (p = 0.02); hospital stay 1.07 versus 3.87 days (p = 0. 00); and mean operative time 175.23 versus 136.94 minutes (p = 0. 003). No woman had a serious complication, and none in the laparoscopy group required a laparotomy. CONCLUSION: Laparoscopic oophorectomy is a safe, highly successful, and cost-effective procedure, although it is associated with a longer operative time than laparotomy.

Adnexal Diseases↗
PubMed1994

Unfolding studies of the protease domain of urokinase-type plasminogen activator: the existence of partly folded states and stable subdomains.

The domain structure and the stability against thermal and chemical denaturation of urokinase-type plasminogen activator (u-PA) have been investigated by NMR spectroscopy and differential scanning calorimetry (DSC). At least five structurally autonomous regions of this three-domain protein have been found to exist. Two of these are the EGF-like and the kringle domains; the others are all within the third domain, which is a serine protease. The latter undergoes three unfolding transitions in its enzymatically active form. Reaction with a specific affinity label (L-Glu-L-Gly-L-Arg-chloromethyl ketone) to produce an inactivated protein results in a stabilization of the structure involved in two of these transitions, and an increase in cooperativity to give a domain which unfolds in two, not three, distinct steps. These are attributed to the denaturation of the two major subdomains of the protease structure. One of the subdomains has exceptional stability, being unfolded only under extreme conditions such as 75 degrees C at pH 2.5 or 4 M GuDCl at pH 4.5 and 29 degrees C. This region has been identified by isolation and characterization of a fragment (residues Ile-159 to Thr-277) obtained by limited proteolysis with thermolysin under conditions where the protease domain was partly unfolded. The NMR data are consistent with this stable region being at the N-terminus of the protein and indicate that its structure and stability are similar to those of the corresponding region of the native protein. These results support the idea that the u-PA protease domain has structural resemblance to the digestive serine proteases, but that stabilizing interactions within the structure can differ significantly between a group of homologous proteins.

Affinity Labels↗
PubMed1994

Psychosocial adjustment to infertility and its treatment: male and female responses at different stages of IVF/ET treatment.

Gender differences in psychosocial adjustment to infertility and its treatment were evaluated amongst a cross-sectional sample of 330 couples, of whom 113 were first time participants and 217 were repeat cycle couples. Whilst 30% of both husbands and wives experienced clinically elevated anxiety regardless of stage of treatment; repeat cycle women (25%) faced the further risk of developing clinically severe depressive symptoms. Significant differences in the amount of care and control received from their spouse and in the degree they suppressed their emotions were reported amongst repeat cycle couples. Any clinical implications of differences in male-female caring styles are discussed within the IVF context. Our results suggest that interventions intended not only to reduce anxiety and depressive symptoms, but also to facilitate ongoing psychosocial functioning, should be implemented for couples at different stages of IVF/ET treatment.

Adaptation, Psychological↗
PubMed1994

Comparative Study in Laparoscopic Oophorectomy

This study was undertaken to determine differences between laparoscopic oophorectomies and oophorectomies performed through a laparotomy in terms of total hospital cost, hospital length of stay, and operative time. From January 1, 1992 to December 31,1992, all patients (57) who had undergone oophorectomies in our hospital were included in the study. Twenty-six of these procedures were laparoscopic. The laparoscopy group had a mean hospital cost of $6,139.00 vs. $7,053.00 for the laparotomy group, a statistically significant difference. The hospital stay for the laparoscopy group was a mean of 1.07 days vs. 3.87 days for the laparotomy group, which was also statistically significant. Operative time for the laparoscopy group was a mean of 175.23 minutes vs. 136.94 minutes for the laparotomy group. This is statistically significant. None of the 57 women had a serious complication. This study demonstrates that laparoscopic oophorectomy is a safe, highly successful, and cost-effective procedure. However, our results indicate that laparoscopic oophorectomy is associated with longer operative times as compared with laparotomy.

Journal Article↗
PubMed1994

Comparison of topical and oral acyclovir in early herpes zoster ophthalmicus.

Poor systemic absorption has limited the efficacy of early oral acyclovir in herpes zoster ophthalmicus (HZO). Aqueous humour levels are substantially higher if the drug is administered topically to the eye. A multicentre open randomised study was performed to compare the ocular prophylactic effects of topical and oral acyclovir. Fifty-seven patients with HZO within 72 hours of the onset of rash received either topical acyclovir ointment or 800 mg oral acyclovir, both 5 times daily for 7 days, and were followed for 12 months. Patients receiving ointment were significantly more likely to have ocular complications (p < 0.02) and anterior uveitis was significantly more frequent (p < 0.01) and severe (p < 0.01). Corneal hypoaesthesia was significantly more frequently (p < 0.05) and severe (p < 0.02) at 1 month. From 2 weeks patients receiving ointment were more likely to have pain and at all times their pain was more severe, but these differences were not statistically significant. In spite of its apparently better penetration topical acyclovir appears to have no prophylactic value in the management of early HZO.

Acyclovir↗
PubMed1994

Treatment of recurrent and metastatic endometrial carcinoma with cisplatin and doxorubicin.

Between April 1985 and February 1989, 19 patients with advanced or recurrent endometrial carcinoma were treated with the combination of cisplatin (50 mg/m2) and doxorubicin (50 mg/m2) administered intravenously every 21 days. Eight patients had Stage III disease, two had Stage IV and nine had recurrent cancer. Eleven patients had measurable disease at the start of therapy. There were 7 partial responses among the 19 patients, for an overall response rate of 36%. The median survival for the whole group was 17 months with a median progression free interval of 5 months. Patients without measurable disease at the onset of therapy had median survivals and progression free intervals which were significantly better than those patients with measurable disease, p < 0.011 and p < 0.025 respectively. Granulocytopenia (< 1000 microliters) occurred in 7 patients. No important thrombocytopenia, cardiotoxicity nephrotoxicity or neurotoxicity was observed. Emesis and alopecia occurred in all patients. No treatment related deaths were encountered.

Aged↗
PubMed1993

Specific regulation of male rat liver cytosolic estrogen receptor by the modulator of the glucocorticoid receptor.

Modulator is a novel low-molecular-weight organic compound that regulates activities of glucocorticoid and mineralocorticoid receptors as well as protein kinase C. In this study we show that male rat liver cytosolic estrogen receptor activation is inhibited by modulator in a dose-dependent manner. Fifty percent inhibition is obtained with 1 unit/ml modulator purified from bovine liver which is within the physiological concentration for modulator. However, sheep uterine cytosolic estrogen and androgen receptors are insensitive to regulation by modulator. Exogenous sodium molybdate treatment inhibits activation of all of these receptors of liver or uterus origin in an identical manner, further differentiating the effects of modulator and the molybdate anion.

Adrenalectomy↗
PubMed1993

Potency of an oxidation-resistant mutant of secretory leukocyte proteinase inhibitor in lipopolysaccharide-induced emphysema in hamsters.

Secretory leukocyte inhibitor (SLPI) is a potent inhibitor of serine proteinases, but sensitive to oxidative inactivation due to a methionine residue in the active centre of the inhibitor. We compared the potency of an oxidation-resistant mutant of recombinant SLPI with native recombinant SLPI in lipopolysaccharide (LPS)-induced emphysema in the hamster. Application of this oxidation-resistant mutant reduced the induced emphysema by 70 and 85% in two separate series of experiments. In contrast, an equal amount of native rSLPI resulted in significantly lower inhibition, 30 and 23%, respectively (P = 0.002). To demonstrate the effect of oxygen radicals upon a single LPS instillation in the lungs, we measured anti-neutrophil elastase activity in lung lavage fluid at 10 and 24 h after the instillation of a mixture of LPS and native rSLPI. We found that residual native rSLPI was only 70 and 55% active, respectively. The rSLPI-mutant remained 93% active in a similar experiment. The native and mutant inhibitor showed equal potency against proteinases in a granule extract of hamster neutrophils. We conclude that the replacement of methionine by leucine in the inhibitory centre of rSLPI results in a decreased sensitivity to oxidative inactivation and that this alone is sufficient to explain the greater efficiency of the rSLPI-mutant in reducing the extent of LPS-induced emphysema.

Animals↗
PubMed1993

Oxidation resistant muteins of antileukoproteinase as potential therapeutic agents.

Native antileukoproteinase (ALP) and two oxidant resistant mutants ALP 242 and ALP 231 were synthesized by means of recombinant DNA technology. In the ALP 242 molecule the methionine residue located in the reactive centre of the binding loop is replaced by a leucine residue. In ALP 231 all four methionine residues of the second domain were substituted by leucine residues. The native inhibitor and the two oxidant resistant molecules show comparable inhibitory capacities towards human neutrophil elastase (HLE) and cathepsin G. All three inhibitors were treated with different reactive oxygen species. After incubation with chloramine T or supernatants of activated polymorphonuclear leukocytes (PMN's) a drastic drop of inhibitory capacity of the native molecule was observed. Compared to the native form of ALP the mutant ALP 242 was less inactivated, whereas ALP 231 was nearly totally resistant towards all reactive oxygen. (Heinzel-Wieland R. et al., Biomed Biochim Acta 50: 677-681 (1991)) The intratracheal administration of HLE into the lung of Syrian Hamsters induced mild to moderate emphysematous lesions. The inhibitory potencies of native ALP and the ALP mutants were determined in this animal model by means of intratracheal instillation of the different molecules one hour prior to the administration of HLE. The inhibitory effects of ALP 242 and ALP 231 towards HLE-induced emphysema were significantly better than that of the native molecule. Surprisingly no significant differences between the two mutants were observed. (Rudolphus A. et al., Clin Sci 81: 777-784 (1991)) In a second animal model the emphysema was induced by repeated intratracheal administration of lipopolysaccharides (LPS) into the hamster lungs. This model is characterized by a chronic process of inflammation probably caused by a continuous release of endogenous elastase from infiltrating PMN's. Repeated applications of 1 mg of ALP 242 reduced the LPS-induced emphysema by 70 to 80%. In contrast, equal amounts of the native molecule resulted in significantly lower inhibition of the LPS-induced emphysema, only 23-30% reduction was observed. Repeated applications of 1 mg of ALP 231 reduced the LPS-induced emphysema only about 50%. So far it is not yet clear, why the totally oxidant resistant ALP 231 was less effective than the ALP 242 molecule. (Stolk J. et al., Pulmonary Pharmacology in press (1992))

Animals↗
PubMed1993

Mood state as a predictor of treatment outcome after in vitro fertilization/embryo transfer technology (IVF/ET).

The association between mood state and treatment outcome after In Vitro Fertilization/Embryo Transfer (IVF/ET) was assessed in a prospective sample of 330 women, of whom 113 were first time participants (inductees) and 217 were repeat cycle women (veterans). Initial evaluation of mood state indicated a significantly higher level of depression amongst veterans than inductees and a significantly greater proportion of veterans (25%) with clinically elevated depression scores compared with inductees (15%) and community norms (approx. 12%). Up to 12 months after initial assessment and after controlling for the number of treatment cycles, a significant difference was observed in the course of pregnancy over time between depressed and non-depressed women. Depressed women exhibited a lower pregnancy rate for the first treatment cycles than non-depressed women. The results and their implications are discussed.

Adult↗