Use of a mechanical simulator to assess pelvic examination skills.
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Clinical Competence↗
Biomedical subjects
W L Heinrichs
Publications and source records attributed to W L Heinrichs.
Simulated learning environments in anatomy and surgery delivered via the next generation internet.
The Next Generation Internet (NGI) will provide high bandwidth, guaranteed Quality of Service, collaboration and security, features that are not available in today's Internet. Applications that take advantage of these features will need to build them into their pedagogic requirements. We present the Anatomy Workbench and the Surgery Workbench, two applications that require most of these features of the NGI. We used pedagogic need and NGI features to define a set of applications that would be difficult to operate on the current Internet, and that would require the features of the NGI. These applications require rich graphics and visualization, and extensive haptic interaction with biomechanical models that represent bony and soft tissue. We are in the process of implementing these applications, and some examples are presented here. An additional feature that we required was that the applications be scalable such that they could run on either on a low-end desktop device with minimal manipulation tools or on a fully outfitted high-end graphic computer with a realistic set of surgical tools. The Anatomy and Surgery Workbenches will be used to test the features of the NGI, and to show the importance of these new features for innovative educational applications.
Anatomy↗
G2H--graphics-to-haptic virtual environment development tool for PC's.
For surgical training and preparations, the existing surgical virtual environments have shown great improvement. However, these improvements are more in the visual aspect. The incorporation of haptics into virtual reality base surgical simulations would enhance the sense of realism greatly. To aid in the development of the haptic surgical virtual environment we have created a graphics to haptic, G2H, virtual environment developer tool. G2H transforms graphical virtual environments (created or imported) to haptic virtual environments without programming. The G2H capability has been demonstrated using the complex 3D pelvic model of Lucy 2.0, the Stanford Visible Female. The pelvis was made haptic using G2H without any further programming effort.
Computer Graphics↗
Virtual body structures: a 3D structure development tool from visible human data.
Understanding the visiospatial aspects of anatomic structures is one of the most important aspects of studying gross anatomy. In this paper we are describing a tool that self-constructs 3D virtual body structures (VBS) 'right in-front-of your-eyes'. Furthermore, manipulation capabilities, such as translucent visualization, interactive rotation, translation, and scaling, incorporated into VBS facilitate fundamental learning experience that leads one to 'build 3D models in the mind', providing a validation of computer-assisted individual learning. Creating 3-D virtual body structures from actual human data has long been a dream of many computer scientists and Medical doctors. Now, with the advances in computer hardware and software technologies, our Virtual Body Structure technique, and the Visible Human project, that dream is becoming a reality.
Anatomy, Cross-Sectional↗
Virtual reality and women's health: a breast biopsy system.
Minimally invasive procedures are becoming much more common in surgical practice because of the many advantages for patient comfort and convenience, and improved surgical access. However some of the major problems leading to occasional surgical errors with this minimal access method are restricted vision, limited sense of touch, difficulties in identification in 3D space of the position of the instrument tips, and their handling during delicate, short-distance movements toward the surgical target area. These factors emphasize the need for computer simulated training in surgical manipulations and procedures in preparation for conducting them in patients. The key new feature of our proof-of-concept training simulator is a preventive mechanism that serves at least two functions. As the surgical target (or a critical structure) is approached, a haptically generated preventive force forewarns the surgeon, making it possible to abort those maneuvers that may lead to adverse results. By announcing a potential collision of a virtual instrument tip with a surgical target, the time used for searching for the target is shortened, and the haptic signal minimizes the potential of tissue damage. This real-time, interactive, virtual reality based, haptic breast biopsy-training simulation is a PC/NT based multitasking, multithreading system. It is based upon an advanced force feedback device. The system monitors and indirectly guides the surgeon's movements, while providing high fidelity visual and force feedback cues as the area of surgical interest is approached. Our first application is with human breast.
Algorithms↗
Enteric nervous system and endometriosis--connection?
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Adult↗
Information frames: a new multimedia approach to Web-based learning of biology and medicine.
Presentation of content in hyperlinked multimedia formats for teaching has failed using the computer's power of navigation through rich visual and auditory information. We have developed "Information Frames", an authoring tool in hypertext markup language (html) format, that allows easy utilization by technology-challenged teachers and professors, and attracts students because of interactive, design-based learning. An Information Frame contains a definition, explanation and illustration of a single concept. Topics are provided with hyperlinks to other Information Frames having related concepts that may provide prerequisite knowledge, or may raise the concept to a more integrative level. A graphical view of the linked-Information Frames presents a Concept Map of the overall topic.
Computer Communication Networks↗
Formative design of a virtual learning environment.
Current technology for 3D visualization, modeling and interaction allows the construction of attractive virtual environments for study of anatomy, surgery and other biomedical fields. The formative methodology for designing such environments is uncharted, but necessary before committing to large scale development. We present one such methodology undertaken during the design of a learning environment for biology for high school and middle school students. We expect to extend this design methodology to the development of environments for the teaching of medical subjects.
Animals↗
Human issues and medical economics of endometriosis. Three- vs. six-month GnRH-agonist therapy.
OBJECTIVE: To project the efficacy and economic consequence of short-term intranasal gonadotropin-releasing hormone agonist (GnRH-a) for diagnosis of and therapy for endometriosis. STUDY DESIGN: Multicenter, placebo-controlled clinical trials of GnRH-a comparing three vs. six months of treatment, three months of retreatment and three months of postoperative treatment for the symptoms and signs of laparoscopically diagnosed endometriosis. RESULTS: The reduction in symptoms and signs of endometriosis was similar at the end of three months to the relief at six months. Retreatment was as effective as initial treatment, and the return of symptoms after laparoscopic surgery plus postoperative treatment for three months was delayed by approximately 18 months as compared to surgery alone. The projected charges for the surgical approaches (laparoscopy or minilaparoscopy) to diagnosis and therapy were 50-60% greater than those for the medical approach. CONCLUSION: GnRH-a administration for three months could be a cost-effective approach to the presumptive diagnosis and treatment of endometriosis among women with chronic pelvic pain.
Administration, Intranasal↗
Therapeutic efficacy and bone mineral density response during and following a three-month re-treatment of endometriosis with nafarelin (Synarel).
OBJECTIVE: Our goal was to determine the effects of a repeated course of the gonadotropin-releasing hormone agonist nafarelin on symptoms and signs of endometriosis and lumbar and distal radius bone mineral density. STUDY DESIGN: Forty-five women previously treated for 6 months with nafarelin, who had recurrent symptoms and signs of endometriosis, received 400 mcg/day of nafarelin intranasally for 3 months. Efficacy was evaluated by changes in severity of symptoms and signs. Lumbar bone mineral density was measured by dual-energy x-ray absorptiometry and distal radius bone mineral density by single-photon absorptiometry. Bone mineral density was also measured in 10 control volunteers. RESULTS: Repeated 3-month treatment significantly alleviated recurrent symptoms and signs of endometriosis. Lumbar bone mineral density decreased significantly by a mean of 2% at the end of treatment; this loss was restored within 3 to 6 months after treatment completion. No bone mineral density decline occurred in the radius. Bone mineral density changes in the control group were statistically insignificant. CONCLUSIONS: A repeated 3-month course of nafarelin treatment significantly relieved recurrent endometriotic symptoms and signs without sustained loss of bone mineral density.
Adult↗
Use of nafarelin versus placebo after reductive laparoscopic surgery for endometriosis.
OBJECTIVE: To evaluate the efficacy of the GnRH agonist (GnRH-a) nafarelin compared with placebo administered for 6 months after reductive laparoscopic surgery for symptomatic endometriosis. DESIGN: Randomized, prospective, placebo-controlled, multicenter clinical trial. SETTING: Thirteen clinics including private practice and university centers. PATIENT(S): One hundred nine women aged 18-47 with laparoscopically proven endometriosis and pelvic pain who had undergone reductive laparoscopic surgery for endometriosis. INTERVENTION(S): Patients were randomized to receive either the GnRH-a nafarelin (200 micrograms twice daily) or placebo for 6 months. MAIN OUTCOME MEASURE(S): Time to initiation of alternative treatment (the length of time from beginning study medication to receiving alternative therapy or to deeming that the study drug was ineffective) and patient-reported and physician-assessed pelvic pain scores. RESULT(S): The median time to initiation of alternative treatment was > 24 months in the nafarelin group versus 11.7 months in the placebo group. Fifteen (31%) of 49 nafarelin-treated patients required alternative therapy, compared with 25 (57%) of 44 placebo-treated patients. The patients' pelvic pain scores dropped significantly in the nafarelin and placebo groups after 6 months of treatment. Physician summary ratings showed significant improvement in the nafarelin group and no significant changes in the placebo group after 6 months of treatment. CONCLUSION(S): Compared with placebo, nafarelin administered after reductive laparoscopic surgery for endometriosis significantly delays the return of endometriosis symptoms requiring further treatment.
Adolescent↗
Interleukin-1 type I receptor messenger ribonucleic acid expression in human endometrium throughout the menstrual cycle.
OBJECTIVE: To investigate the messenger ribonucleic acid (mRNA) expression of interleukin-1 (IL-1) type I receptor in the endometrial tissue of normal patients during the menstrual cycle. DESIGN: Prospective longitudinal study. SETTING: Department of Obstetrics and Gynecology, Stanford University Medical Center, Stanford, California. PATIENTS: Twenty fertile women between 19 and 41 years of age underwent hysterectomy for benign reasons (n = 9) and laparoscopy for tubal ligation (n = 11). In all cases, endometriosis was not visualized. INTERVENTIONS: Endometrial biopsy using the Novak curette was obtained at the time of surgery. MAIN OUTCOME MEASURE: Total RNA extracted from unfractioned endometrial tissue was analyzed on Northern blots by using specific complementary deoxyribonucleic acid probes. RESULTS: We found IL-1 type I receptor mRNA expression in endometrial tissue throughout the entire menstrual cycle. However, IL-1 type I receptor mRNA levels were significantly higher during both early and late luteal phases than follicular and midluteal phases. CONCLUSIONS: Our results demonstrate the presence of the IL-1 system in the human endometrium and that the receptor is regulated throughout the menstrual cycle with a 4.1-fold increased expression of the IL-1 receptor gene in the early luteal phase compared with preovulatory endometrium.
Adult↗
Noninvasive determination of ulnar stiffness from mechanical response--in vivo comparison of stiffness and bone mineral content in humans.
An approach referred to as Mechanical Response Tissue Analysis (MRTA) has been developed for the noninvasive determination of mechanical properties of the constituents of the intact limb. Of specific interest in the present study is the bending stiffness of the ulna. The point mechanical impedance properties in the low frequency regime, between 60 and 1,600 Hz are used. The procedure requires a proper design of the probe for good contact of the skin at midshaft and proper support of the proximal and distal ends of the forearm to obtain an approximation to "simple support" of the ulna. A seven-parameter model for the mechanical response is then valid, which includes the first mode of anterior-posterior beam bending of the ulna, the damping and spring effect of the soft tissue between probe and bone, and the damping of musculature. A dynamic analyzer (HP3562A) provides in seconds the impedance curve and the pole-zero curve fit. The physical parameters are obtained from a closed-form solution in terms of the curve-fit parameters. The procedure is automated and is robust and analytically reliable at about the five percent level. Some 80 human subjects have been evaluated by this mechanical response system and by the Norland single photon absorptiometer, providing for the first time in vivo, a comparison of elastic bending stiffness (ulna) and bone mineral content (radius). Three functional parameters of potential clinical value are the cross-sectional bending stiffness EI, the axial load capability Pcr (Euler buckling load) and the bone "sufficiency" S, defined as the ratio of Pcr to body weight. The correlation between EI and bone mineral (r = 0.81) is only slightly less than previous in vitro results with both measurements on the same bone (r = 0.89). When sufficiency is taken into consideration, the correlation of Pcr and bone mineral content is improved (r = 0.89). An implication is that "quality" of bone is a factor which is not indicated by bone mineral content but which is indicated by stiffness. Bone mineral is necessary for proper stiffness but not sufficient. Therefore mechanical measurement should provide a new dimension to be used toward a better understanding of the factors related to bone health and disease.
Biomechanical Phenomena↗
Successful treatment of pulmonary lymphangiomyomatosis with oophorectomy and progesterone.
A 35-yr-old woman, with profound dyspnea at rest and failure to thrive, asked to be evaluated at Stanford Medical Center. She requested a second opinion after entering death counseling in another institution because of an unrelenting, deteriorating course caused by pulmonary lymphangiomyomatosis. Her recurring right chylous pleural effusion was drained by chest tube, a LaVeen shunt was placed to decompress her severe chylous ascites, an oophorectomy was performed, large dose progesterone (medroxyprogesterone acetate) was initiated intramuscularly, and during her hospitalization she was fed by total parenteral nutrition. She was discharged mildly improved after 2 months. Now, 3 yr later, her pulmonary function tests and chest radiographs are improved, and she walks 2 miles per day and teaches school full time. Extensive hormonal analysis did not reveal an endocrinologic abnormality that could explain the pathophysiology of her disease. However, the patient had multiple human chorionic gonadotropin injections before becoming ill, as have a number of other patients who have developed this disease. This report is an example of successful treatment of severe pulmonary lymphangiomyomatosis.
Adult↗
Reproductive hazards of the workplace and the home.
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Environmental Exposure↗
Differentiation of sex steroid-binding protein in adult rhesus monkeys.
Several species of primates have sex differences in sex steroid-binding protein (SBP), female adults having higher serum binding capacities (micrograms of dihydrotestosterone bound per deciliter) than male adults, e.g., male humans, 1.28 +/- 0.4; human females, 2.86 +4- 0.9; Macaca nemestrina male animals, 5.62 +/- 1.24; Macaca nemestrina female animals, 11.07 +/- 1.85 (means +/- standard deviations). SBP correlates inversely with metabolic clearance rates of testosterone (T). The sex difference was identified in rhesus monkeys, six per group, evaluated 4 years after postpubertal castration: male animals 3.95 +/- 1.14; female animals 5.85 +/- 0.98 (p less than 0.05). Estradiol-17 beta (E2) pellets producing physiologic levels of E2 in female monkeys obliterated the sex difference by increasing SBP in male animals. After withdrawal of E2, physiologic levels of T in male monkeys produced a marked decrease in SBP levels (p less than 0.01), and the sex difference reappeared; castrated female animals and prenatally androgenized female animals responded similarly to T (2.81 +/- 0.81 and 2.64 +/- 0.49, respectively). Both values were greater (p less than 0.05) than that of the male group (2.02 +/- 0.33). These data suggest that the sex steroid milieu influences the binding capacity of SBP for potent androgens in adulthood but that the differentiation of the SBP sex in rhesus monkeys is determined by factors other than prenatal androgen exposure.
Animals↗
A practical approach to the patient with dysmenorrhea.
Pelvic pain associated with the menses may be a result of physiologic problems, premenstrual tension syndrome, primary dysmenorrhea or secondary dysmenorrhea. All of these conditions may be caused by both physiologic and psychologic factors. An accurate diagnosis requies a complete history and physical examination and astute assessment of predisposing or aggravating conditions. Diagnosis has been improved through the use of laparoscopy, hysteroscopy, hysterosalpingography and dilatation and curettage. Treatment has been revolutionized with the use of oral contraceptives and prostaglandin synthesis inhibitors. These diagnostic and therapeutic advances now enable the sympathetic physician to effectively evaluate and treat almost all patients with menstrually related pelvic pain. When all of these approaches fail, the physician should consider psychiatric consultation or referral to pain clinic or gynecologist with special interest in this field.
Contraceptives, Oral, Synthetic↗
Differentiation and regulation of peripheral androgen metabolism in rats and rhesus monkeys.
The sex-unique metabolic network for steroids is induced neonatally in male rats. The metabolic clearance rates (MCR) of dehydroepiandrosterone and testosterone are similar for both sexes of rats despite quantitatively significant sex differences in individual enzyme activities of adults; neonatally androgenized females had a 2-to 3-fold increase in MCR but cyproterone had no effect. The MCRT and MCRDHA of castrated adult male rhesus monkeys are the same as those of normal males; the MCRDHA is 4-fold greater. Testosterone treatment suppressed the MCRDHA of the castrated groups but estradiol treatment did not. The sex-steroid binding protein (SBP) levels were lower in males than females, and these values were reduced by testosterone. Estrogen suppressed the higher SBP values of females. The sex-steroid milieu of adult rhesus monkeys regulates SBP binding capacity and the enzyme activities of skin measured in vitro. Prenatal testosterone does not exert a crucial role in presetting the peripheral metabolic network in rhesus monkeys.
Age Factors↗