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Biomedical subjects

B Evans

Publications and source records attributed to B Evans.

At least 55 records · Page 3Linked to original sources
PubMed1998

Superovulation with a high gonadotropin dose for in vitro fertilization: is it effective?

PURPOSE: Our purpose was to investigate the effect on the ovarian response of increasing the gonadotropin dose. METHODS: We analyzed retrospectively the in vitro fertilization data for patients who had two cycles of treatment, with a higher dose in cycle 2. The patients were stratified according to age, ovarian response, and gonadotropin dose in the first cycle. The main outcome measure was the number of follicles, eggs, and embryos and the peak estradiol (E2) level. RESULTS: The study included 244 patients. Patients in both age groups (n = 118, < or = 33 years; n = 126, > 33 years), low (n = 66) and intermediate (n = 145) responders, and patients who received < 225 IU follicle-stimulating hormone (n = 175) in cycle 1 had a better response in cycle 2. However, the high responders (n = 33) and those who received 225 or 300 IU follicle-stimulating hormone (n = 69) in cycle 1 showed a similar response in both cycles, except for a significantly higher E2 level in cycle 2. CONCLUSIONS: Our results indicate that exceeding a daily dose of 300 IU is unrewarding.

Adult↗
PubMed1998

Lung volume histograms after computed tomography of the chest with three-dimensional imaging as a method to substantiate successful surgical expansion of the rib cage in achondroplasia.

The authors describe a radiographic method to quantify a surgical procedure of thoracic expansion in a 2-year-old patient with achondroplasia, small chest cage, and severe restrictive lung disease. The patient had undergone three surgical procedures of thoracic expansion since birth. The authors utilized computer-generated lung volume histograms after spiral computed tomographic scanning and three-dimensional imaging of the lungs to calculate his lung volumes before and after the third surgical thoracic expansion. The lung volumes, calculated by the histograms, were 363 mL and 406 mL before and after surgery, respectively. This 40-mL difference in the patient's lung volumes (4 mL/kg) accounted for a significant clinical improvement. Lung volume histograms obtained by this radiographic method are very helpful in substantiating a successful surgical chest expansion or provide an explanation for an unsuccessful repair.

Achondroplasia↗
PubMed1998

Adaptation of the bioprogressive philosophy to use brackets with .022" slots.

The Bioprogressive orthodontic treatment philosophy is traditionally associated with the use of brackets that have .018" slots. Proponents of the Bioprogressive philosophy suggest this slot configuration largely because they believe that lighter wires provide force levels that are within the biological limits of the periodontal support system. At the same time, the principles of orthodontic anchorage advocated by the Bioprogressive philosophy depend on careful torque control of both molar and anterior teeth. It is possible and sometimes advisable to use wires designed for use in brackets with .018" slots, in brackets with .022" slots. Under these circumstances, the thinner wires may not provide sufficient control over torque moments to develop the required degree of molar anchorage. This article suggests that with the use of certain wires, and with minor modifications to the shapes of arches, that the use of brackets with .022" slots need not conflict with many of the important principles of orthodontic treatment advocated in the Bioprogressive philosophy.

Chromium Alloys↗
PubMed1997

Expression of tissue type plasminogen activator and type 1 plasminogen activator inhibitor, and persistent fibrin deposition in chronic renal allograft failure.

Persistent fibrin deposition has been observed in kidneys undergoing chronic rejection, and has been suggested to contribute to the obliteration of the vasculature in these grafts. The mechanisms leading to it are not clear. Fibrinolysis, the process to remove fibrin in tissues, is initiated by tissue type plasminogen activator (tPA) and suppressed by type 1 plasminogen activator inhibitor (PAI-1). To investigate their roles in chronic rejection and fibrin deposition, we serially examined the expression of tPA and PAI-1 in an unmodified chronic rejection model, using a Fisher 344 to Lewis rat renal transplant, at 0, 2, 4, 6, 10, 12, 16 and 20 weeks post-transplantation (N = 4 rats/time point in each group). We also analyzed fibrin deposition and the development of chronic changes in the grafts. Our results show that tPA was up-regulated only in the acute phase of rejection (P < 0.05), whereas PAI-1 was induced and persistently expressed during the progressive phase of chronic rejection, together with persistent fibrin deposition in the grafts. Immunohistochemistry showed PAI-1 was mainly localized to the damaged/proliferative vascular intima. The results suggest that persistent induction of PAI-1 may be responsible for the continuance of fibrin deposition, which is associated with irreversible damage and chronic graft loss.

Animals↗
PubMed1997

Population density and cancer mortality by gender and age in England and Wales and the Western World 1963-93.

The aetiology of malignant disease is multi-factorial, including contributory environmental factors. Based upon the premise that increases in the density of population will be coterminous with a worsening of the environment, it is hypothesised that such changes should be reflected in an increase in cancer mortality in general and in elderly populations. By focusing upon changes in the elderly (+75) deaths between two time periods, the study corrects for age factors related to cancer mortality. The study tests this hypothesis via correlations between population density and malignancy death rates in general and elderly age bands over a thirty year period. It was found that there were positive and significant correlations between population density and malignancy mortality rates in the Western World, especially amongst men, but all correlations strengthened in the direction hypothesised. The findings were not an artefact of longevity, further research is required to give a better understanding of these findings.

Adult↗
PubMed1997

Risk analysis and international trade principles applied to the importation into Canada of caprine embryos from South Africa.

Between November 1994 and February 1995 over nine thousand Boer goat embryos were imported into Canada from the Republic of South Africa. This substantial international movement of animal genetics via embryos was achieved through the application of the risk analysis principles prescribed in Section 1.4. of the International Animal Health Code of the Office International des Epizooties (OIE). Integral to the development of the health certification procedures was the application of the fundamental principles of non-discrimination, harmonisation, equivalence and transparency defined in the World Trade Organisation Agreement on Sanitary and Phytosanitary measures. Risk mitigation interventions were founded upon full consideration of the potential for disease transmission by animal embryos as espoused by the International Embryo Transfer Society and the relevant standards contained in Appendix 4.2.3.3. of the OIE International Animal Health Code. All the embryos imported into Canada were implanted into synchronised recipients on arrival. Twenty months later there has been no evidence of disease in either the recipient animals or the resulting animals born in Canada.

Animals↗
PubMed1996

Site-directed mutagenesis, kinetic, and spectroscopic studies of the P-loop residues in a low molecular weight protein tyrosine phosphatase.

The structure of the specific phosphate binding loop (P-loop) of bovine protein tyrosine phosphatase (BPTP) is very similar to that present in high M(r) PTPases. Site-directed mutagenesis was used to explore the role of several conserved residues involved in forming the P-loop of BPTP. Thus, Ser-19 and Ser-43 were individually mutated to alanines, and Asn-15 was mutated to alanine and glutamine. The 1H NMR spectra of the mutants showed good conservation of global secondary structure when compared to wild-type enzyme. Kinetic measurements revealed that only S19A and N15A had substantially altered catalytic activities toward p-nitrophenyl phosphate at pH 5.0, with both mutants exhibiting Vmax values that were 0.25-0.33% of wild-type enzyme. Further kinetic analyses of the N15A and S19A mutants were performed using phosphomonoester substrates with varied phenolic leaving groups. For S19A, the slope of the correlation between Vmax and the substrate leaving group pKa was significantly altered, consistent with a change of the rate-determining step from dephosphorylation to phosphorylation. This was confirmed by partitioning experiments employing methanol as an alternative nucleophile in the dephosphorylation step. Thus, mutating Ser-19 to alanine reduced the efficiency of nucleophilic attack by Cys-12. It is concluded that Ser-19 acts to facilitate the ionization and orientation of Cys-12 for optimal reaction as a nucleophile and as a leaving group. It also appears that Asn-15, Ser-19, His-72, and to a lesser extent Ser-43 serve structural functions that allow the active site to adopt an optimal geometry for phosphate binding. The Asn-15 to Ala mutation appears to disrupt the hydrogen-bonding network, with an accompanying alteration of the geometry of the P-loop. These conclusions are also consistent with changes in the stability of the respective proteins, as measured by urea denaturation.

Amino Acid Sequence↗
PubMed1996

Comparison of cancer deaths in England and Wales and the developed world by age and gender 1973-92, and, new malignancies in England and Wales 1971-88.

Cancer deaths in England and Wales and the developed world were examined by age and gender between 1973-1992. Whilst over-all mortality levels increased, this was mainly linked to extended longevity, as the rate fell substantially for people under 55 in the majority of countries, possibly as a result of improved treatment and prevention outcomes. Whilst England and Wales had above average reductions in cancer deaths, especially for children, there were considerable rises in new malignancies, 1971-88, particularly amongst women under 35 years, and in certain selected sites. These over-all changes do not appear to be the result of improved diagnosis, thus, despite evidence of more effective therapeutic and preventative measures the incidence of new malignancies is increasing. The possible implications are briefly discussed, in the context of "medical audit', which increasing uses mortality rates as "indicators of effectiveness'.

Adolescent↗
PubMed1996

Nurses performing embryo transfer: successful outcome of in-vitro fertilization.

This prospective study demonstrates the feasibility and outcome of embryo transfer performed by nursing staff with medical cover available. Of 771 patients who had embryo transfer, 679 (88%) had their embryo transfer performed by a nurse. In 92 cases (12%) a doctor performed the embryo transfer, either as the first operator, or having been brought in to assist the nurse who experienced difficulty. The pregnancies per transfer for nurse transfer was 246/679 (36%) and where a doctor performed the transfer 20/68 (29%). These data show a high comparable success rate when a nurse performed the embryo transfer, and a low incidence of direct medical involvement.

Embryo Transfer↗
PubMed1996

CD45RO and CD45RA positive cell populations in idiopathic membranous and IgA glomerulopathy.

AIMS: To immunophenotype and quantitate glomerular and interstitial inflammatory cells in cases of idiopathic membranous and IgA glomerulopathy; to correlate cell numbers with aspects of clinical data and renal function. METHODS: Routine indirect immunoperoxidase staining was performed on frozen section renal biopsy specimens for T and B lymphocyte related antigens, macrophages and MHC class II antigens. Double immunohistochemical staining was performed to identify CD45RO+ and CD45RA+ cells. RESULTS: In IgA glomerulopathy correlations were found relating interstitial cell numbers to creatinine concentration at biopsy (CD45RO+ and CD45RA+ cells) and follow up creatinine concentration (CD3+, CD4+, CD8+, CD45RO+, and CD45RA+ cells). Also in IgA glomerulopathy mean arterial pressure at biopsy correlated with interstitial cell numbers and most recent follow up creatinine concentration. There were no correlations between glomerular inflammatory cells and renal function in either disease. Double staining showed that although most glomerular CD45RO+ and CD45RA+ cells were macrophages, positive cells in the interstitium were lymphocytes. The interstitial CD45RO+:RA+ ratio in normal renal biopsy specimens was approximately 5:1; for IgA glomerulopathy it was 1.5 and was 1.0 in idiopathic membranous glomerulopathy. CONCLUSIONS: This study demonstrates that interstitial, and not glomerular, inflammatory cell numbers correlate with renal function in primary glomerular disease and that double staining is necessary to interpret positive immunostaining for antigens located on more than one type of inflammatory cell. Detailed investigation of the interstitial CD45RO+ and CD45RA+ cells may give an insight into the pathogenesis of glomerular disease.

Adolescent↗
PubMed1996

The mental health of children in foster care: a comparison with community and clinical samples.

OBJECTIVE: To determine whether the psychiatric profile of children in foster care is more similar to clinical or community profiles. METHOD: Caregiver and teacher ratings of DSM-III-R externalizing and internalizing symptoms were collected for 3 groups of children: children in foster care, children assessed at a children's mental health centre, and a community sample. RESULTS: Children in foster care approximated the numbers and types of symptoms of the clinical sample. Coming from a family on social assistance, having a parent with a criminal history, and being of the male gender were correlated with higher externalizing and internalizing symptom scores independent of group membership. Group membership accounted for less than 5% of the variance in psychiatric symptom scores. CONCLUSIONS: The high symptom burden of children in care is substantially attributable to their high-risk histories, and treatment should be designed with this in mind.

Adolescent↗
PubMed1996

The Delorme procedure: a useful operation for complicated rectal prolapse in the elderly.

Full thickness rectal prolapse is a distressing and debilitating condition that often affects elderly patients. Fecal incontinence is usually present. Frequently, comorbid conditions or previous pelvic procedures complicate surgical care. A perineal approach may be used in these patients to avoid the complications of pelvic surgery and general anesthesia. The Delorme operation involves mucosal stripping and muscle plication of the rectal prolapse and is performed externally under regional or general anesthesia. We report our experience with this procedure in six elderly candidates who have undergone the Delorme procedure at the UCLA Center for Health Sciences in the past year. Two men and four women with a mean age of 78 +/- 12 years were followed over a mean of 11 +/- 4 months. Complicating factors included a mean of 1.7 failed prolapse operations per patient (0-6), pelvic radiation in two patients, and severe cardiac and pulmonary disease in two patients. Outpatient bowel preparations and same day admissions were used. Operative time averaged 80 minutes. No blood transfusions were required and postoperative stay averaged 2.7 days. A total of 67 per cent report improvement in continence. There was no major morbidity or mortality and only one recurrence. We conclude that the Delorme procedure is a safe and useful procedure for the treatment of complete rectal prolapse. Elderly patients, patients with failed prolapse operations, and those with prior pelvic surgery or radiation should be considered for this procedure.

Aged↗
PubMed1995

Discovery of an orally bioavailable NK1 receptor antagonist, (2S,3S)-(2-methoxy-5-tetrazol-1-ylbenzyl)(2-phenylpiperidin-3-yl)amine (GR203040), with potent antiemetic activity.

The antiemetic, pharmacokinetic, and metabolic profile of CP-99,994, a potent NK1 receptor antagonist, has been carefully evaluated. As a result we began a medicinal chemistry program which initially identified a 3-furanyl analogue (6) with improved antiemetic potency and a methyl sulfone (5) with enhanced metabolic stability and oral bioavailability. The improved pharmacokinetic profile of methyl sulfone (5) was associated with its low lipophilicity, and a therefore a number of heterocyclic analogues with reduced log D were synthesized. Out of this program emerged 19 (GR203040), a tetrazolyl-substituted analogue. Tetrazole 19 inhibits radiation-induced emesis in the ferret with high potency when administered both subcutaneously and orally, has a long duration of action, and has high oral bioavailability in the dog. Tetrazole 19 is currently undergoing evaluation as a novel approach for the control of emesis associated with, for example, cancer chemotherapy.

Animals↗