Biomedical subjects

Colin Birch

Publications and source records attributed to Colin Birch.

8 recordsLinked to original sources

PubMed2006

Onset of sheath extension and duration of lamina extension are major determinants of the response of maize lamina length to plant density.

BACKGROUND AND AIMS: Plants regulate their architecture strongly in response to density, and there is evidence that this involves changes in the duration of leaf extension. This questions the approximation, central in crop models, that development follows a fixed thermal time schedule. The aim of this research is to investigate, using maize as a model, how the kinetics of extension of grass leaves change with density, and to propose directions for inclusion of this regulation in plant models. METHODS: Periodic dissection of plants allowed the establishment of the kinetics of lamina and sheath extension for two contrasting sowing densities. The temperature of the growing zone was measured with thermocouples. Two-phase (exponential plus linear) models were fitted to the data, allowing analysis of the timing of the phase changes of extension, and the extension rate of sheaths and blades during both phases. KEY RESULTS: The duration of lamina extension dictated the variation in lamina length between treatments. The lower phytomers were longer at high density, with delayed onset of sheath extension allowing more time for the lamina to extend. In the upper phytomers--which were shorter at high density--the laminae had a lower relative extension rate (RER) in the exponential phase and delayed onset of linear extension, and less time available for extension since early sheath extension was not delayed. CONCLUSIONS: The relative timing of the onset of fast extension of the lamina with that of sheath development is the main determinant of the response of lamina length to density. Evidence is presented that the contrasting behaviour of lower and upper phytomers is related to differing regulation of sheath ontogeny before and after panicle initiation. A conceptual model is proposed to explain how the observed asynchrony between lamina and sheath development is regulated.

Kinetics↗

PubMed2006

Trans-obturator surgery for stress urinary incontinence: 1-year follow-up of a cohort of 52 women.

This study was a 1-year follow-up of a cohort of 52 women who underwent trans-obturator tape (TOT) procedures using Obtape. Follow-up information was available for 45/52 (87%) women. The rate of erosions was 8/52 (15%). Among 34 women examined, 26% experienced tenderness on palpation of operative site, and 72% were objectively cured on pad test. Forty women completed questionnaires (median Incontinence Impact Questionnaire-7, 0; median Urogenital Distress Inventory-6, 17) and of those, 93% would recommend TOT to a friend. We found a high rate of erosions among our cohort. Our high rate of erosions may be a result of our review of the majority of the cohort, and it is likely related to the specific device used (Obtape). The majority of women were satisfied with the outcome. Before introducing new procedures into widespread clinical practice, it is important to rigorously investigate their outcomes.

Aged↗

PubMed2006

Five cases of tape erosion after transobturator surgery for urinary incontinence.

BACKGROUND: Before introducing the transobturator tape into our practice we undertook 52 transobturator tape procedures. The transobturator tape procedures were undertaken with an "outside-in" approach, using nonwoven polypropylene mesh with average pore size of 50 mum. CASES: Five cases of vaginal erosions have been identified, 1 complicated by a groin abscess. All cases required further procedures to trim (n = 3), resect (n = 1) or remove (n = 1) the tape. One woman had a tension-free vaginal tape procedure. To date, 3 women remain incontinent. CONCLUSION: Possible reasons for the complications include 1) surgical inexperience (unlikely, given that we have undertaken more than 2000 tension-free vaginal tape procedures without similar complication rates); 2) inherent susceptibility of the "hammock" position of the transobturator tape; or 3) the nonwoven polypropylene tape with mesh size of 50 microm itself may predispose to erosion or abscess.

Adult↗

PubMed2005

The use of prosthetics in pelvic reconstructive surgery.

With an ageing population, increasing numbers of women are presenting with pelvic floor disorders. The lifetime risk of undergoing prolapse or incontinence surgery in the USA is 1 in 11. With a recognized reoperation rate exceeding 30% for prolapse surgery, attempts are being made to improve our primary surgical outcomes. The introduction of synthetic and biological prostheses have been proposed to reduce recurrence rates whilst maintaining vaginal capacity and coital function. The role of synthetic prostheses is well established for use in continence surgery in the form of midurethral slings and for abdominal sacrocolpopexy to correct vault prolapse. However, postoperative morbidity-specifically the risk of mesh erosion-has limited their use for vaginal prolapse surgery. Biological prostheses have been introduced to offer an alternative for use in these repairs. While these grafts largely obviate the problem of erosion there are concerns regarding longevity, and only short-term outcome data are currently available. The role of prosthetics in pelvic floor surgery is an evolving and controversial field. Current and future research should be directed at evaluating the safety and efficacy of specific products and comparison of subjective and objective outcome parameters to standard surgical techniques for pelvic organ prolapse.

Biocompatible Materials↗

PubMed2003

The management of uterine leiomyomas.

OBJECTIVE: The objective of this document is to serve as a guideline to the investigation and management of uterine leiomyomas. OPTIONS: The areas of clinical practice considered in formulating this guideline are assessment, medical treatments, conservative treatments of myolysis, selective artery occlusion, and surgical alternatives including myomectomy and hysterectomy. The risk-to-benefit ratio must be examined individually by the woman and her health-care provider. OUTCOMES: Implementation of this guideline should optimize the decision-making process of women and their health-care providers in proceeding with further investigation or therapy for uterine leiomyomas, having considered the disease process and available treatment options, and reviewed the risks and anticipated benefits. EVIDENCE: English-language articles from MEDLINE, PubMed, and the Cochrane Database were reviewed from 1992 to 2002, using the key words "leiomyoma," "fibroid," "uterine artery embolization," "uterine artery occlusion," "uterine leiomyosarcoma," and "myomectomy." The level of evidence has been determined using the criteria described by the Canadian Task Force on the Periodic Health Examination. BENEFITS, HARMS, AND COSTS: The majority of fibroids are asymptomatic and will not require intervention or further investigations. For the symptomatic fibroid, hysterectomy offers a definitive solution. However, it is not the preferred solution for women who wish to preserve their uterus. The predicted benefits of alternative therapies must be carefully weighed against the possible risks of these therapies. In the properly selected woman with symptomatic fibroids, the result from the selected treatment should be an improvement in the quality of life. The cost of the therapy to the health-care system and to women with fibroids must be interpreted in the context of the cost of untreated disease conditions and the cost of ongoing or repeat treatment modalities. RECOMMENDATIONS: 1. Medical management should be tailored to the needs of the woman presenting with uterine fibroids and geared to alleviating the symptoms. Cost and side effects of medical therapies may limit their long-term use. (III-C) 2. In women who do not wish to preserve fertility and who have been counselled regarding the alternatives and risks, hysterectomy may be offered as the definitive treatment for symptomatic uterine fibroids and is associated with a high level of satisfaction. (II-A) 3. Myomectomy is an option for women who wish to preserve their uterus, but women should be counselled regarding the risk of requiring further intervention. (II-B) 4. Hysteroscopic myomectomy should be considered as first-line conservative surgical therapy for the management of symptomatic intracavitary fibroids. (I-B) 5. It is important to monitor ongoing fluid balance carefully during hysteroscopic removal of fibroids. (I-B) 6. Laparoscopic myolysis may present an alternative to myomectomy or hysterectomy for selected women with symptomatic intramural or subserous fibroids who wish to preserve their uterus but do not desire future fertility. (II-B) 7. Uterine artery occlusion may be offered as an alternative to selected women with symptomatic uterine fibroids who wish to preserve their uterus. (I-C) 8. Women choosing uterine artery occlusion for the treatment of fibroids should be counselled regarding possible risks, and that long-term data regarding efficacy, fecundity, pregnancy outcomes, and patient satisfaction are lacking. (III-C) 9. Removal of fibroids that distort the uterine cavity may be indicated in infertile women, where no other factors have been identified, and in women about to undergo in vitro fertilization treatment. (III-C) 10. Concern of possible complications related to fibroids in pregnancy is not an indication for myomectomy, except in women who have experienced a previous pregnancy with complications related to these fibroids. (III-C) 11. Women who have fibroids detected in pregnancy may require additional fetal surveillance when the placenta is implanted over or in close proximity to hen the placenta is implanted over or in close proximity to a fibroid. (III-C) 12. In women who present with acute hemorrhage related to uterine fibroids, conservative management consisting of estrogens, hysteroscopy, or dilatation and curettage may be considered, but hysterectomy may become necessary in some cases. (III-C) 13. Hormone replacement therapy may cause myoma growth in postmenopausal women, but it does not appear to cause clinical symptoms. Postmenopausal bleeding and pain in women with fibroids should be investigated in the same way as in women without fibroids. (II-B) 14. There is currently no evidence to substantiate performing a hysterectomy for an asymptomatic leiomyoma for the sole purpose of alleviating the concern that it may be malignant. (III-C) VALIDATION: This guideline was reviewed and accepted by the Clinical Practice Gynaecology Committee, and by Executive and Council of the Society of Obstetricians and Gynaecologists of Canada. SPONSOR: The Society for Obstetricians and Gynaecologists of Canada.

Adult↗

PubMed2003

Emergency contraception.

OBJECTIVE: To review current knowledge about emergency contraception (EC), including available options, their modes of action, efficacy, safety, and the effective provision of EC within a practice setting. OPTIONS: The combined estradiol-levonorgestrel (Yuzpe regimen) and the levonorgestrel-only regimen, as well as post-coital copper intrauterine devices, are reviewed. OUTCOMES: Efficacy in terms of reduction in risk of pregnancy, safety, and side effects of methods for EC and the effect of the means of access to EC on its appropriate use and the use of consistent contraception. EVIDENCE: MEDLINE and the Cochrane Database were searched for English-language articles published from January 1998 through March 2003, to update the previous SOGC guidelines published in 2000. Clinical guidelines and position papers developed by health or family planning organizations were also reviewed. Key words used were: emergency contraception, post-coital contraception, emergency contraceptive pills, postcoital copper IUD. VALUES: The studies reviewed were classified according to criteria described by the Canadian Task Force on the Periodic Health Exam and the recommendations for practice were ranked based on this classification. BENEFITS, HARMS, AND COSTS: These guidelines are intended to help reduce unintended pregnancies by increasing awareness and appropriate use of EC. RECOMMENDATIONS: 1. Women who have had unprotected intercourse and wish to prevent pregnancy should be offered hormonal EC up to 5 days after intercourse. (II-2A) 2. A copper IUD can be used up to 7 days after intercourse in women who have no contraindications. (III-B) 3. Women should be advised that the levonorgestrel EC regimen is more effective and causes fewer side effects than the Yuzpe regimen. (I-A) 4. Either 1 double dose of the levonorgestrel EC regimen (1.5 mg) or the regular 2-dose levonorgestrel regimen (0.75 mg each dose) may be used, as they have similar efficacy with no difference in side effects. (I-A) 5. Hormonal EC should be started as soon as possible after unprotected sexual intercourse. (II-2B)6. Women of reproductive age should be provided with a prescription for hormonal EC in advance of need. (I-A) 7. The woman should be evaluated for pregnancy if menses have not begun within 21 days following EC treatment. (III-A) 8. A pelvic examination is not indicated for the provision of hormonal EC. (III-A) Validation: These guidelines have been reviewed by the Clinical Practice Gynaecology and Social and Sexual Issues Committees of the Society of Obstetricians and Gynaecologists of Canada. SPONSOR: The Society of Obstetricians and Gynaecologists of Canada.

Canada↗

PubMed2002

The role of synthetic and biological prostheses in reconstructive pelvic floor surgery.

PURPOSE OF REVIEW: Uterovaginal prolapse and urinary incontinence are common problems whose pathogenesis remains unclear. As life expectancy increases, significantly greater numbers of women will present with pelvic floor prolapse and incontinence requiring surgical intervention. Currently, the lifetime risk of undergoing prolapse or continence surgery in the USA is one in 11, and up to 30% of patients will require repeat prolapse and 10% repeat continence surgery. In an attempt to improve surgical outcomes and to preserve vaginal capacity and coital function, a number of synthetic and biological prostheses have been developed. This review aims to look at the controversies that exist as the 'ideal' prosthetic material is developed. RECENT FINDINGS: The recent literature has reflected the increasing interest in the use of biological prostheses (Allograft/Xenograft) and synthetic absorbable meshes. There has been a focus on the risk factors for erosion seen with the use of synthetic non-absorbable material and a review of techniques for the reduction and management of this complication. The advent of mesh placement in minimally invasive continence surgery (tension-free vaginal tape, intravaginal sling, and Supra Public ARC) is now seeing surgical success to 5 years, but the reporting of complications remains inconsistent. SUMMARY: The use of prosthetics in pelvic floor and continence surgery is an evolving field. Further randomized controlled trials are required to evaluate the role of both biological and synthetic prostheses in reconstructive surgery, to determine which type of prosthesis is most suitable for specific procedures. Prosthetic reinforcement should not be used to replace good surgical techniques.

Bioprosthesis↗

PubMed2002

SOGC clinical guidelines. Hysterectomy.

OBJECTIVE: To identify the indications for hysterectomy, preoperative assessment, and available alternatives required prior to hysterectomy. Patient self-reported outcomes of hysterectomy have revealed high levels of patient satisfaction. These may be maximized by careful preoperative assessment and discussion of other treatment choices. In most cases hysterectomy is performed to relieve symptoms and improve quality of life. The patient's preference regarding treatment alternatives must be considered carefully. OPTIONS: The areas of clinical practice considered in formulating this guideline are preoperative assessment including alternative treatments, choice of method for hysterectomy, and evaluation of risks and benefits. The risk-to-benefit ratio must be examined individually by the woman and her health practitioners. OUTCOMES: Optimizing the decision-making process of women and their caregivers in proceeding with a hysterectomy having considered the disease process, and available alternative treatments and options, and having reviewed the risks and anticipated benefits. EVIDENCE: Using Medline, PubMed, and the Cochrane Database, English language articles were reviewed from 1996 to 2001 as well as the review published in the 1996 SOGC guidelines. The level of evidence has been determined using the criteria described by the Canadian Task Force on the Periodic Health Examination. BENEFITS, HARMS, AND COSTS: Hysterectomy is the treatment of choice for certain gynaecologic conditions. The predicted advantages must be carefully weighed against the possible risks of the surgery and other treatment alternatives. In the properly selected patient, the result from the surgery should be an improvement in the quality of life. The cost of the surgery to the health care system and to the patient must be interpreted in the context of the cost of untreated conditions. The approach selected for the hysterectomy will impact on the cost of the surgery. RECOMMENDATIONS: Benign Disease 1. Leiomyomas: For symptomatic fibroids, hysterectomy provides a permanent solution to menorrhagia and the pressure symptoms related to an enlarged uterus. (I-A) 2. Abnormal uterine bleeding: Endometrial lesions must be excluded and medical alternatives should be considered as a first line of therapy. (III-B) 3. Endometriosis: Hysterectomy is often indicated in the presence of severe symptoms with failure of other treatments and when fertility is no longer desired. (1-B) 4. Pelvic relaxation: A surgical solution usually includes vaginal hysterectomy, but must include pelvic supporting procedures. (II-B) 5. Pelvic pain: A multidisciplinary approach is recommended, as there is little evidence that hysterectomy will cure chronic pelvic pain. When the pain is confined to dysmenorrhea or associated with significant pelvic disease, hysterectomy may offer relief. (II-C) Preinvasive Disease 1. Hysterectomy is usually indicated for endometrial hyperplasia with atypia. (I-A) 2. Cervical intraepithelial neoplasia in itself is not an indication for hysterectomy. (I-B) 3. Simple hysterectomy is an option for treatment of adenocarcinoma in situ of the cervix when invasive disease has been excluded. (I-B) Invasive Disease 1. Hysterectomy is an accepted treatment or staging procedure for endometrial carcinoma. It may play a role in the staging or treatment of cervical, epithelial ovarian, and fallopian tube carcinoma. (I-A) Acute Conditions 1. Hysterectomy is indicated for intractable postpartum hemorrhage when conservative therapy has failed to control bleeding. (II-B) 2. Tubo-ovarian abscesses that are ruptured or do not respond to antibiotics may be treated with hysterectomy and bilateral salpingo-oophorectomy in selected cases. (I-C) 3. Hysterectomy may be required for cases of acute menorrhagia refractory to medical or conservative surgical treatment. (II-C) Other Indications 1. Consultation with an oncologist or geneticist is recommended when considering hysterectomy and prophylactic oophorectomy for a familial history of ovarian cancer. (III-C) Surgical Approach 1. The vaginal route shoe should be considered as a first choice for all benign indications. The laparoscopic approach should be considered when it reduces the need for a laparotomy. (III-B) VALIDATION: Medline searches were performed in preparing this guideline with input from experts in their field across Canada. The guideline was reviewed and accepted by SOGC Council and Executive. SPONSOR: The Society of Obstetricians and Gynaecologists of Canada.

Algorithms↗