Biomedical subjects

R Knapp

Publications and source records attributed to R Knapp.

At least 19 recordsLinked to original sources

PubMed2002

Primary lymphatic metastatic spread in testicular cancer occurs ventral to the lumbar vessels.

OBJECTIVES: To analyze whether primary metastatic spread occurs behind the lumbar vessels and whether removal is necessary for accurate staging in diagnostic retroperitoneal lymph node dissection, because dissection of lymphatic tissue behind the lumbar vessels is a challenging maneuver. METHODS: One hundred thirty-nine patients were included in our study. Twenty-nine patients with clinical Stage I tumor underwent laparoscopic staging lymph node dissection, including removal of the lymph nodes behind the lumbar vessels. Sixty-four patients with Stage II testicular cancer were retrospectively examined by computed tomography to determine the localization of the enlarged lymph nodes in relation to the lumbar vessels. On the basis of these results, 49 patients with clinical Stage I underwent laparoscopic lymph node dissection within the same template but without dissection of the lymphatic tissue behind the lumbar vessels. RESULTS: In the first group, 10 of 29 patients had pathologic Stage IIA tumors, with positive nodes exclusively ventral to the lumbar vessels. In group 2, 39 patients with solitary metastatic lesions had enlarged lymph nodes, which were always ventral to the lumbar vessels. Only in 3 of 25 patients with multiple metastases was one enlarged node found behind the lumbar vessels. In group 3, no tumor recurrence either before or behind the lumbar vessels could be found in 46 patients after a mean follow-up of 27.8 months. CONCLUSIONS: On the basis of these data, we believe that primary lymphatic metastatic spread in testicular cancer always occurs ventral to the lumbar vessels. Therefore, the removal of lymphatic tissue behind the lumbar vessels for diagnostic procedures is not necessary.

Humans↗

PubMed2001

Spontaneous remission in a secondary acute myelogenous leukaemia following invasive pulmonary aspergillosis.

Spontaneous remission of adult acute myelogenous leukaemia (AML) represents a rare event. We report a 60-year-old female patient suffering from secondary AML M1 and severe invasive pulmonary hyalohyphomycosis highly suggestive of aspergillosis. Two months after the diagnosis of leukaemia, she achieved a spontaneous remission lasting 3 months, although neither cytostatic drugs nor corticoids were administered because of a septic condition. At the time of remission, a chronic hepatitis C virus infection and a polyclonal hypergammaglobulinaemia were present, and the patient received granulocyte colony-stimulating factor once. This report represents the first documentation of a spontaneous remission in AML following invasive pulmonary hyalohyphomycosis. Possible mechanisms of this phenomenon are discussed.

Aspergillosis↗

PubMed2001

The craniofacial anomalies archive at St. Louis Children's Hospital: 20 years of craniofacial imaging experience.

This article describes how the Craniofacial Imaging Laboratory at the Cleft Palate and Craniofacial Deformities Institute, St. Louis Children's Hospital, Washington University Medical Center, has developed an electronic archive for the storage of computed tomography image digital data that is independent of scanner hardware and independent of units of storage media (i.e., floppy disks and optical disks). The archive represents one of the largest repositories of high-quality computed tomography data of children with craniofacial deformities in the world. Archiving reconstructed image data is essential for comparative imaging, surgical simulation, quantitative analysis, and use with solid model fabrication (e.g., stereolithography). One tertiary craniofacial center's experience in the establishment and maintenance of such an archive through three generations of storage technology is reported. The current archive is housed on an external 35-GB hard drive attached to a Windows-based desktop server. Data in the archive were categorized by specific demographics into groups of patients, number of scans, and diagnoses. The Craniofacial Imaging Laboratory archive currently contains computed tomography image digital data for 1827 individual scans. The earliest scan was done in 1980; the most recently stored scan for the purposes of this report occurred in May of 2000. The average number of scans archived per complete year was 94, with a range of 59 to 138. Of the 1827 total scans, 74 percent could be classified into specific diagnostic categories. The majority of the archive (55 percent) is composed of the following five diagnoses: sagittal synostosis (17 percent), unilateral coronal synostosis (11 percent), hemifacial microsomia (10 percent), plagiocephaly without synostosis (10 percent), and metopic synostosis (7 percent). Storage of computed tomography image data in a digital archive currently allows for continuous upgrading of image display and analysis and facilitates longitudinal and cross-sectional studies, both intramural and extramural. Internet access for clinical and research purposes is feasible, but contingent on protection of patient confidentiality. The future of digital imaging regarding craniofacial computed tomography scan storage and processing is also discussed.

Child↗

PubMed2001

The influence of age on the response of major depression to electroconvulsive therapy: a C.O.R.E. Report.

As part of a C.O.R.E., multi-site longitudinal study comparing continuation electroconvulsive therapy (ECT) vs. continuation pharmacotherapy, the authors determined the response of 253 patients with major depression to acute-phase, bilateral ECT by use of the 24-item Hamilton Rating Scale for Depression. Remission rates for three age-groups, > or =65 years; 46-64 years; and < or =45 years, were 90 percent, 89.8 percent, and 70 percent, respectively. Age, as a continuous variable, positively influenced response to treatment. Bilateral, dose-titrated ECT is a highly effective acute treatment for major depression, and older age confers a greater likelihood of achieving remission.

Age Factors↗

PubMed2000

Disturbance of venous flow patterns in patients with transient global amnesia.

Transient global amnesia (TGA) is an inability to form new memories. The pathophysiology and cause of TGA have not been defined. We examined the changes of internal jugular venous flow patterns in 21 patients with TGA and 21 age-matched and sex-matched controls using duplex ultrasonography during two Valsalva manoeuvres (blocking venous return through the superior vena cava). During both manoeuvres a retrograde flow component was seen significantly more frequently in the TGA group than in the controls. Ten patients reported Valsalva-like activities preceding TGA. In these patients a retrograde flow component took place more frequently than in those who did not report preceding Valsalva-like activities. Our results lend support to the hypothesis that TGA may be attributable to venous congestion, and consequent venous ischaemia to bilateral diencephalic or hippocampal structures.

Aged↗

PubMed2000

Plasma steroid-binding globulin mediation of differences in stress reactivity in alternative male phenotypes in tree lizards, Urosaurus ornatus.

Plasma steroid-binding globulins, for example, corticosteroid-binding globulin and sex hormone-binding globulin (SHBG), have been identified in a number of vertebrates. One possible function of these proteins is to regulate the amount of steroid delivery to target tissues, as only free steroids are believed to diffuse from the circulation to target cells. Male tree lizards, Urosaurus ornatus, exhibit alternative male reproductive tactics correlated with dewlap (throat-fan) coloration. Males with orange-blue dewlaps are aggressive and territorial, whereas males with orange dewlaps are less aggressive and employ a satellite strategy. The two types of males have similar basal levels of total plasma corticosterone and testosterone. However, testosterone levels of nonterritorial males are more sensitive than those of territorial males to negative regulation by stress-induced increases in corticosterone. We tested the hypothesis that this difference in corticosterone feedback on testosterone could be mediated, in part, by differences in binding globulin levels between the two types of males. We have identified two steroid-binding globulins in male tree lizards. The first binds androgens and estradiol with high affinity (10(-9) M) and is similar to previously described sex hormone-binding globulins. The second binds both androgens and C(21) steroids, such as progesterone and corticosterone, with higher specificity than estradiol and is best described as an androgen-glucocorticoid-binding globulin (AGBG). In both types of males, the capacity of AGBG is much higher than SHBG. In addition, AGBG capacity is significantly greater in territorial than nonterritorial males, whereas the capacity of SHBG does not differ between the two types of males. Calculations of free steroid levels based on the affinity and capacity measures suggest that although most testosterone circulates bound to binding globulins, binding capacity is high enough that binding globulins are also able to bind to other steroids such as corticosterone. Thus, differences in binding capacity between the two types of males could result in higher levels of free corticosterone in nonterritorial males than in territorial males, especially during stress-induced increases in corticosterone, and may explain why testosterone levels of nonterritorial males are more sensitive to negative feedback by corticosterone.

Aggression↗

PubMed2000

Long-term follow-up of the Stockholm screening study on ovarian cancer.

OBJECTIVES: Seventy percent of ovarian cancer is diagnosed at advanced stages. Having a method for early diagnosis is a very attractive concept. Several attempts have been made, using monoclonal antibody-based immunoassays, ultrasound, or combinations of both, to identify methods that might prove to be sufficiently sensitive and specific as a screening test. Despite promising results, a mortality study of a large population has yet to be completed due in part to the high cost involved. METHODS: One of the first studies aimed at devising a screening strategy for ovarian cancer used the CA 125 immunoassay followed by ultrasound. The study was performed in Stockholm from 1986 through 1988. Ten years now having passed, an analysis has been performed to further evaluate the results of that study. RESULTS: Screening led to the diagnosis of ovarian cancer in six patients, five of whom have since died of the disease. By searching the Cancer Registry, we were able to identify 20 ovarian cancer patients who developed the disease after the screening period. Of these, 12 died of the disease, 2 are alive with disease, and 6 have no evidence of disease following treatment. The median survival for patients diagnosed by screening was 100 months. Median survival for ovarian cancer patients identified subsequent to screening was 20 months. Although there was no difference in survival between these two groups, median survival was better for women diagnosed by screening (borderline significance, P = 0.059). CONCLUSION: These results indicate that a study of a large number of women with a sufficiently long observation time will be required to establish whether or not screening can reduce ovarian cancer mortality. Such a study may also provide insight into the natural history of ovarian cancer.

Adult↗

PubMed2000

The value of the World Wide Web for tele-education in radiology.

We assessed Websites for radiological education. Of several hundred sites identified, 30 were randomly selected for evaluation by two groups of observers. All Web pages were rated with respect to time required to access the information; structure and organization of the site; image quality; and information content and relevancy. Rapid access was gained to many educational radiology Websites, which contained large numbers of interesting radiological images of good quality. A weak point was the structure and organization of the sites. The greatest variability in ratings was found in the information content and relevancy of the Websites.

Evaluation Studies as Topic↗

PubMed1999

Early development of the motor and premotor circuitry of a sexually dimorphic vocal pathway in a teleost fish.

The plainfin midshipman fish (Porichthys notatus) has a caudal hindbrain vocal motor circuit that has been proposed to share a common embryonic origin with the hindbrain vocal networks of other vertebrates. In midshipman, this vocal circuit includes three groups of neurons: sonic motor, pacemaker, and ventral medullary. Here, transneuronal transport of biocytin or neurobiotin was used to delineate the early ontogeny of the three hindbrain vocal nuclei and their pattern of connectivity. The organization of the vocal nuclei was studied in animals beginning soon after hatching until the nuclei have the adult phenotype at the time fish become free-swimming. There is a clear sequence of events whereby motoneurons establish their connections with the sonic muscle prior to establishing connections with premotor neurons; developmental milestones of the vocal pathway parallel those of the sonic muscle. The results also indicate that sexual differentiation of the vocal motor system in midshipman begins early in development, well before any evidence of sexual maturation. Embryonic males and females differ in the relationship between soma size and body length for the three hindbrain nuclei. Males are also more variable than females in body mass, volume of the sonic motor nucleus, and motoneuron cell size.

Aging↗

PubMed1999

Steroid hormones and paternal care in the plainfin midshipman fish (Porichthys notatus).

The present study investigated the relationship between plasma steroid hormone levels and the expression ofpaternal behavior in the plainfin midshipman fish (Porichthys notatus), where males may simultaneously care for multiple clutches in different stages of development. Blood samples were collected from free-living parental males during that part of the breeding season when males may be found in various stages of parental care. Plasma 11-ketotestosterone levels were significantly higher in males with empty nests and nests containing only eggs than in males with nests containing embryos. All males with nests containing embryos had undetectable testosterone levels, whereas testosterone levels were detectable in many males with empty nests or nests containing only eggs. Estradiol levels were detectable in only a few males from nests with no eggs or nests containing only eggs. Cortisol levels were not correlated with stage of paternal care or with handling time. These results follow the frequently reported vertebrate pattern of declining androgen levels over the course of the breeding season or during the period of parental care. However, many male midshipman guarding nests containing only eggs had androgen levels similar to those of males whose nests contained no offspring. Thus the pattern of androgen levels exhibited by reproductively active parental male midshipman may reflect a compromise between investment in paternal care versus courtship and/or territoriality.

Animals↗

PubMed1999

Injury of the rectum during vaginal surgery.

OBJECTIVE: We sought to report our experience with injury of the rectum during vaginal surgery. STUDY DESIGN: A retrospective chart review of a vaginal surgery database was performed. RESULTS: Nine injuries were identified. Four patients with posthysterectomy vault prolapse incurred a rectal laceration just above the perineum during an attempt to develop the rectovaginal space. Another rectal laceration occurred just above the perineum during an attempt to develop the rectovaginal space during vaginectomy-hysterectomy for gender dysphoria. Three other injuries occurred between the vaginal cuff and peritoneum while posterior culdotomy for vaginal hysterectomy was attempted. The remaining injury was in a Schuchardt incision. All 9 injuries were recognized, repaired, and healed without complication. CONCLUSIONS: Laceration of the rectum is an uncommon complication of vaginal surgery. Prompt recognition and repair result in uncomplicated primary healing.

Female↗

PubMed1999

Virtual reality and anthropology.

Since the discovery of the Tyrolean Iceman in 1991 advanced imaging and post processing techniques were successfully applied in anthropology. Specific techniques include spiral computed tomography and 3-dimensional reconstructions including stereolithographic and fused deposition modeling of volume data sets. The Iceman's skull was the first to be reproduced using stereolithography, before this method was successfully applied in preoperative planning. With the advent of high-end graphics workstations and biomedical image processing software packages, 3-dimensional reconstructions were established as a routine tool for analyzing volume data sets. These techniques opened totally new insights in the field of physical anthropology. Computed tomography became the ideal research tool to access the internal structures of various precious fossils without damaging or even touching them. Many of the most precious specimens from the species Autralopithecus (1.8-3.5 Myears), Homo heidelbergensis (200-600 kyears) or Homo neanderthalensis (40-100 kyears) were scanned during the last 5 years. Often the fossils are filled with a stone matrix or other materials. During the postprocessing routines highly advanced algorithms were used to remove virtually these incrustations. Thus it was possible to visualize the morphological structures that lie beneath the matrix. Some specimen were partially destroyed, so the missing parts were reconstructed on computer screen in order to get estimations of the brain volume and endocranial morphology, both major fields of interest in physical anthropology. Moreover the computerized form of the data allows new descriptions of morphologic structures by the means of 'geometric morphometrics'. Some of the results may change aspects and interpretations in human evolution. The introduction of new imaging and post processing techniques created a new field of research: Virtual Anthropology.

Algorithms↗

PubMed1999

Synergistic interactions between ampakines and antipsychotic drugs.

Tests were made for interactions between antipsychotic drugs and compounds that enhance synaptic currents mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid-type glutamate receptors ("ampakines"). Typical and atypical antipsychotic drugs decreased methamphetamine-induced hyperactivity in rats; the effects of near or even subthreshold doses of the antipsychotics were greatly enhanced by the ampakines. Interactions between the ampakine CX516 and low doses of different antipsychotics were generally additive and often synergistic. The ampakine did not exacerbate neuroleptic-induced catalepsy, indicating that the interaction between the different pharmacological classes was selective. These results suggest that positive modulators of cortical glutamatergic systems may be useful adjuncts in treating schizophrenia.

Animals↗

PubMed1999

Respirator triggering of electron beam computed tomography (EBCT): research on vital capacities.

In this project we evaluate the dynamic changes during expiration at different levels of positive-end-expiratory pressure (PEEP) in ventilated patients. We wanted to discriminate between normal lung function and acute respiratory distress syndrome (ARDS). After approval by the local Ethic Committee we studied two ventilated patients: (one with normal lung function and one with ARDS) We used the 50 ms scan mode of the EBCT. The beam was positioned 1 cm above the diaphragm while the table position remained unchanged. We developed an electronic trigger that utilizes the respirator's synchronizing signal to start the EBCT at the onset of expiration. During controlled mechanical expiration at two levels of PEEP (0 and 15 cm H2O), pulmonary aeration was rated as: well-aerated (-900HU to -500HU), poorly aerated (-500HU to -100HU) and non-aerated (-100HU to +100HU). Pathological and normal lung functions showed different dynamic changes. The different PEEP levels resulted in a significant change of pulmonary aeration in the same patient. Although we studied only two patients, respiratory triggered EBCT may be accurate in discriminating pathological changes due to the abnormal lung function in a mechanically ventilated patient.

Adult↗

PubMed1999

New methods and techniques in anthropology.

Since the discovery of the Tyrolean Iceman in 1991, advanced imaging and post-processing techniques have been successfully applied to anthropological research. Among the specific techniques are spiral computed tomography and 3-dimensional reconstructions, which include stereolithographic and fused deposition modeling of volume data sets. The Iceman's skull was the first to be produced using stereolithography; subsequently, it has been successfully applied in preoperative planning. With the advent of high-end performance graphics workstations and biomedical image processing software packages, 3-dimensional reconstructions have become established as routine tools for analyzing volume data sets. These techniques enabled dramatically new insights to be gained in the field of physical anthropology. Computed tomography became the ideal research tool to access the internal structures of various precious fossils without even touching--let alone damaging--them. Among the most precious are specimens from the genus Australopithecus (1.8 Myr-3.5 Myr), as well as representatives of Homo heidelbergensis (200 kyr-600 kyr) and Homo neanderthalensis (40 kyr-100 kyr); such fossils have been CT-scanned during the last five years. The fossils often are filled with a stone matrix or other encrustations. During the post-processing routines, highly advanced algorithms were used to remove these encrustations virtually (the concrete fossils remain untouched). Thus it has been possible to visualize the morphological structures that are hidden by the matrix layer. Some specimens have been partially destroyed, but it has been possible for the missing parts were reconstructed on the computer screen in order to get estimations of brain volume and endocranial morphology, both major fields of interest in physical anthropology. Moreover, the data in computerized form allows new descriptions of morphological structures using geometric morphometrics. Some of the results may change aspects and interpretations in human evolution and approaches to long-standing questions in this field. We subsume the introduction of these new imaging and post-processing techniques into a new field of research: Virtual Anthropology.

Animals↗

PubMed1998

Restoration of voluntary emptying of the bladder by transplantation of innervated free skeletal muscle.

BACKGROUND: On the basis of studies with animals and experience with functioning muscle transfer in plastic surgery, we have developed a surgical technique to restore detrusor function for patients with bladder acontractility in whom there is no treatment alternative. METHODS: Three patients (aged 26 years, 28 years, and 68 years) with bladder acontractility as a result of spinal-cord injury (two patients) and chronic overdistension (one patient), who required catheterisation for bladder emptying for 5 years, 2 years, and 2 years, respectively, took part in our study. The patients were treated with microneurovascular free transfer of autologous latissimus dorsi muscle to the bladder to restore detrusor function. Follow-up included clinical and urodynamic evaluation, colour doppler sonography, intravenous urography, and flow-mode computerised tomography. FINDINGS: The three patients voluntarily emptied their bladders at 16 weeks, 16 weeks, and 30 weeks after surgery, respectively. There was no need for further catheterisation throughout the follow-up period. On urodynamic assessment at 12 months after the operation bladder capacity was found to be 600 mL, 600 mL, and 650 mL, residual urinary volume 0 mL, 50 mL, 90 mL, and maximum flow rate 26 mL/s, 25 mL/s, and 18 mL/s, respectively. Activity at the transplanted latissimus dorsi was confirmed by ultrasonography and flow-mode computerised tomography. INTERPRETATION: Microneurovascular free transfer of latissimus dorsi muscle to functionally restore a deficient detrusor muscle has proved to be successful for the three patients in our study. This technique may also be an option to restore the function of other smooth-muscle organs.

Adult↗

PubMed1998

[Spinal trauma].

In the workup of patients suffering from spinal trauma the radiologist is eager to make a proper diagnosis asking only for few additional examinations. This can be done by a functional and biomechanical approach in reading standard radiographs. With the knowledge of the kind of injury expected the whole extent of posttraumatic changes in the spine can be delineated exactly. The goal is to make a diagnosis that answers questions of stability so the traumatologist can be aided in therapy.

Diagnosis, Differential↗

PubMed1998

Intraurethral ultrasound: diagnostic evaluation of the striated urethral sphincter in incontinent females.

The aim of our study was to evaluate the striated urethral sphincter (rhabdosphincter) in incontinent females by means of intraurethral ultrasound (IUUS). Thirty-four incontinent and 11 continent female patients were examined by means of 12.5-MHz endoluminal ultrasound (US). The distance between the inner contour of the sphincter muscle and the US catheter was measured in the contracted and the non-contracted condition. The US findings were correlated with those obtained by urodynamic studies. Partial or complete loss of sphincter function was detected in patients with stress urinary incontinence (SUI). Reduced sphincter function was not observed in patients with urge incontinence and continent volunteers. The findings on US were found to correlate well with the grade of SUI. The IUUS technique offers the benefit of direct visualization of the sphincter mechanism. Therefore, endoluminal US may become an important adjunct in the diagnostic evaluation of SUI and will possibly provide new insights for a better therapeutic strategy.

Adult↗