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R Knapp

Publications and source records attributed to R Knapp.

At least 37 records · Page 2Linked to original sources
PubMed1998

Three-dimensional computed tomography of the reconstructed lower urinary tract: technique and findings.

The aim of this pilot study in 54 patients was to improve the visualization of the anatomy and postoperative changes in the pelvic topography after bilateral ureteroileal urethrostomy, using surface rendering of electron beam CT (EBCT) data for the 3D display. Fifty-four patients (39 men and 15 women) were scanned with an EBCT unit between 3 and 110 months after performing orthotopic ureteroileal urethrostomy ("Hemi-Kock") or ureteroileal rectosigmoidostomy. Various parameters and spatial viewing points were used in the 3D reconstruction, which was performed interactively on external workstations with commercially available software. The anti-reflux nipple was visualized as a distinct structure in all patients. In 8 patients with an interval of more than 12 months between surgery and CT, the pouch had developed an ovoid shape almost indistinguishable from the original bladder. The segmented data sets were partly animated to display the anatomy as virtual endoscopy. Three-dimensional depiction and virtual endoscopy of the neobladder using EBCT are a new way of imaging the postoperative anatomy. Its clinical efficacy in the diagnosis of inconclusive postoperative morbidity, especially voiding problems, and planning of necessary therapy have to be the subject of further evaluation.

Adult↗
PubMed1998

3-Dimensional computerized tomography and virtual reality endoscopy of the reconstructed lower urinary tract.

PURPOSE: We describe postoperative surgical anatomy after orthotopic reconstruction of the lower urinary tract using 3-dimensional (D) computerized tomography (CT) and virtual reality endoscopy. MATERIALS AND METHODS: Electronic beam CT was performed in 39 men and 15 women a mean of 60 years old with an orthotopic ileal neobladder (50) or ureteroileal rectosigmoidostomy (4), followed by 3-D reconstruction of the pelvic anatomical structures using specialized computer hardware and software. The mean interval between surgery and CT was 15 months (range 3 to 110) and the mean interval between 2 subsequent 3-D CT studies in 22 patients was 6 months (range 3 to 9). RESULTS: CT time with the patient on the table was 45 minutes and computerized 3-D reconstruction time with the patient off the table was 4 to 5 hours. The pouch had a smooth ovoid shape in 66 and 82% of the patients on the first and second 3-D CT studies, respectively. Mean length of the antireflux nipple was 4 cm. (range 2.5 to 8) and mean length of the afferent limb was 6 cm. (range 3 to 15). There were no radiologically significant sex specific differences in the shape or dimensions of the urinary reservoirs, except for a tendency toward more acute angles between the pouch and remnant urethra. No pathological findings were visible on 3-D CT that were not also evident on conventional CT. CONCLUSIONS: Three-D CT may be clinically useful for surgical planning of a lower abdominal reoperation or unexplained findings and symptoms in patients with bladder substitutions. Cost and time expenditures for processing preclude its routine use in all cases. Virtual reality endoscopy may be a valuable tool for teaching and scientific purposes.

Adult↗
PubMed1997

Male morphs in tree lizards have different testosterone responses to elevated levels of corticosterone.

Changes in circulating glucocorticoid and androgen levels mediate agonistic behaviors in many vertebrates. Individual variation in the magnitude of the glucocorticoid response to stressful stimuli, the negative effects of elevated glucocorticoid levels on androgen levels, or both could mediate individual differences in subsequent agonistic behavior. In a series of previous studies, we found that both alternative male reproductive morphs in the tree lizard, Urosaurus ornatus, can exhibit elevated levels of plasma corticosterone following male-male encounters, but that the territorial morph appears less likely to exhibit coincident decreases in plasma testosterone. Two studies tested the hypothesis that the two morphs differ in the degree to which testosterone levels are influenced by elevated corticosterone levels. In the first study, physically restraining males elicited endogenous elevations of circulating corticosterone levels. Testosterone levels were significantly negatively correlated with corticosterone levels in the nonterritorial morph, but there was no correlation between levels of the two steroids in territorial males. In the second study, corticosterone levels were artificially elevated in free-living male tree lizards using a noninvasive dermal patch. This exogenous elevation of corticosterone significantly depressed testosterone levels in both morphs, but it produced a significantly greater depression in the nonterritorial morph. Nonterritorial males appear to be more sensitive than territorial males to the testosterone-suppressing effects of elevated circulating levels of corticosterone. This difference between the morphs in the effects of a stress hormone on the reproductive axis may be a fundamental part of the mechanism (1) underlying behavioral tactic switching within the nonterritorial morph or (2) contributing to behavioral differences between the morphs.

Administration, Cutaneous↗
PubMed1997

New onset hypertension after extracorporeal shock wave lithotripsy: age related incidence and prediction by intrarenal resistive index.

PURPOSE: In a recent study we found an increased resistive index immediately after extracorporeal shock wave lithotripsy (ESWL) in patients older than 60 years, which suggests renovascular disturbance. The present 26-month followup study was undertaken to investigate the relevance of elevated resistive index levels and the incidence of new onset hypertension. MATERIALS AND METHODS: Of the initial 76 patients 57, including 20 of the 23 at risk patients 60 or greater years, group 3), were followed for more than 26 +/- 6 months after ESWL. Followup included 2 resistive index measurements by Doppler ultrasound of the treated and the contralateral kidney, at least 2 blood pressure measurements 1 week apart and excretory urography as well as determination of plasma renin activity in 9 patients. RESULTS: With 1 exception, elevated resistive index levels and hypertension were observed exclusively in patients older than 60 years. In these patients the resistive index ranged between 0.65 and 0.86 (mean plus or minus standard deviation 0.74 +/- 0.05, normal less than 0.7). This increase in resistive index was statistically significant (p < 0.0001). Compared to the levels obtained immediately after ESWL, the resistive index continued to increase in all 9 patients older than 60 years who had hypertension (45%), whereas in the normotensive patients the resistive index was either stable or decreased. There was a strong positive correlation (0.903) between pathological resistive index levels and blood pressure. CONCLUSIONS: Patients older than 60 years are at risk for disturbances of renal perfusion as assessed by the resistive index, and 45% of these patients have new onset hypertension within 26 months of treatment.

Adolescent↗
PubMed1997

Sympathetic mediation of stress and aggressive competition: plasma catecholamines in free-living male tree lizards.

The sympathetic nervous system and adrenal catecholaminergic tissue act to prepare an animal for "fight or flight" by release of catecholamines into synapses and plasma. However, few studies have measured plasma catecholamines in nonmammalian vertebrates and none have measured them in free-living animals. We report plasma levels of norepinephrine (NE), epinephrine (EPI) and dopamine (DA) in free-living tree lizards (Urosaurus ornatus) bled in the field: 1) immediately after capture, 2) after 10 minutes of restraint, 3) immediately after a staged territorial encounter and 4) four minutes after the end of a staged territorial encounter. Time to capture and time to bleed after capture were also recorded for each sample. Time to capture had little effect on plasma catecholamines suggesting that plasma catecholamines do not rise during the brief pursuit by the investigator necessary to capture the lizards in the field. In contrast, plasma NE and EPI increased during blood collection. However, this response was very consistent allowing comparisons to be made using analysis of covariance to control for time to bleed. Results indicate that restraint stress caused a large increase in plasma levels of NE, E and DA. Plasma levels of NE and E, but not plasma DA, were also significantly elevated both immediately and 4 minutes after aggressive encounters, although less so than following restraint stress. These studies show that stress and aggression activate the sympatho-adrenal system. This activation could be involved in behavioral changes during aggression, meeting metabolic demands of the encounter, or both.

Adrenal Glands↗
PubMed1997

Effects of the cholecystokinin agonist pentagastrin in patients with generalized anxiety disorder.

OBJECTIVE: The anxiogenic and panicogenic effects of peripheral administration of the cholecystokinin-B receptor agonist pentagastrin and placebo were evaluated in patients with generalized anxiety disorder and normal comparison subjects. METHODS: Seven patients with generalized anxiety disorder and seven age- and sex-matched normal subjects received an intravenous bolus of placebo and pentagastrin. RESULTS: Panic attacks occurred in five patients with generalized anxiety disorder (71%) and in one normal subject (14%). Patients with generalized anxiety disorder were more likely to report more nonpanic anxiety than were normal subjects. CONCLUSIONS: Patients with generalized anxiety disorder appear to exhibit greater subjective sensitivity to pentagastrin than do normal subjects.

Anxiety Disorders↗
PubMed1996

Evidence for a graft-versus-tumor effect in a patient treated with marrow ablative chemotherapy and allogeneic bone marrow transplantation for breast cancer.

Graft-versus-leukemia (GvL) has been shown to be an important immune-mediated antitumor effect in hematologic malignancies. It is still unknown whether such an immunemediated antitumor effect has clinical implications in patients with solid tumors. A 32-year-old woman with inflammatory breast cancer received a bone marrow transplant (BMT) from her HLA-identical sibling. During graft-versus-host disease (GvHD) cytotoxic T lymphocytes were grown and tested in a chromium-release assay against B and T lymphocytes of the patient and donor and against a panel of breast cancer cell lines. Resolution of liver metastases was observed simultaneously with clinical GvHD in the first weeks after transplant. In addition, minor histocompatibility antigen (MiHA)-specific and major histocompatibility complex (MHC) class I antigen-restricted cytotoxic T lymphocytes recognizing breast carcinoma target cells were isolated from the blood of the patient. Pretreatment of such target cells with tumor necrosis factor (TNF)-alpha but not with interferon (IFN)-alpha or IFN-gamma increased susceptibility of these cells to lysis by cytotoxic T lymphocytes. Clinical course and in vitro results suggest that a graft-versus-tumor (GvT) effect might exist after allogeneic BMT for breast cancer. However, clinical experience on a larger scale would be required to determine the clinical efficacy of GvT effects in patients with solid tumors.

Adult↗
PubMed1996

Blood pressure changes after extracorporeal shock wave nephrolithotripsy: prediction by intrarenal resistive index.

In order to identify a high-risk group for the development of arterial hypertension after extracorporeal shock wave nephrolithotripsy (ESWL), we correlated the increase in renovascular resistance induced by ESWL in 79 normotensive patients with changes in arterial blood pressure occurring 20 (+/- 3) months after therapy. Renal vascular resistance was measured as resistive index (RI) by duplex Doppler sonography in both kidneys. Mean RI before treatment was 0.620 +/- 0.035 (SD). After treatment, we observed a significant and age-dependent increase in the RI in the treated kidney to 0.673 +/- 0.06. Of the patients with a post-ESWL RI > 0.690, 39% developed hypertension. Posttherapy RI values surpassing 0.690 showed a 0.8 sensitivity and a 0.7 specificity in predicting arterial hypertension. Intrarenal Doppler ultrasound (US) is useful to find the high-risk group for arterial hypertension after ESWL.

Adolescent↗
PubMed1995

Hormonal responses to aggression vary in different types of agonistic encounters in male tree lizards, Urosaurus ornatus.

Hormonal responses to male-male interactions have been detected in some studies of vertebrates but not others. One hypothesis that may partially explain these discrepancies is that differences in the duration of male-male interactions cause different hormonal responses. In social systems based on dominance-subordinance hierarchies interactions often last longer than if exclusive territories are maintained. Tests of the hypothesis that encounter duration explains discrepancies in hormonal responses would be facilitated by a species that shows elements of both types of social systems, such as species in which males practice alternative reproductive tactics. We compared plasma levels of corticosterone and testosterone in males of the territorial morph of the tree lizard (Urosaurus ornatus) subjected either to short (15 min) male-male encounters or to long (7 days) dominance interactions. In the long interactions, dominant males had lower levels of corticosterone than did subordinate males over the first day, but this difference subsequently disappeared. In sharp contrast, winners of short-term encounters had elevated plasma corticosterone levels which peaked the day after the encounter. Thus, males isolated after a short encounter experienced an increase in corticosterone that was apparently inhibited in males who continued interacting with other males. The delayed increase in corticosterone after a short encounter may facilitate metabolic recovery from the encounter, mobilize metabolic substrates useful in subsequent encounters, or may alter subsequent behavior. The response does not appear to be simply recovery from exercise because in a second experiment males exercised for 15 min did not show a similar delayed increase in corticosterone the following day. Testosterone levels were also monitored and did not change in any of these treatments. These results demonstrate that the duration and the outcome of male-male interactions may each independently influence hormone levels.

Adrenal Cortex Hormones↗
PubMed1995

Location of neurons projecting to the hypophysial stalk--median eminence in ring doves (Streptopelia roseogrisea).

The median eminence/pituitary stalk represents the final common pathway for fibers from neurons that project to the pituitary gland. We have used the lipophilic fluorescent tracer 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) to determine the location of neurons projecting to the median eminence/pituitary stalk in ring doves. The tracer can be precisely applied to fixed tissue, in areas to which it is otherwise difficult to gain access. Following application of DiI to the median eminence/pituitary stalk, labeled neurons were detected in six distinct regions: the ventro-medial hypothalamic nucleus, paraventricular nucleus, supraoptic nucleus, in and ventral to the lateral forebrain bundle, preoptic area, and lateral septum. Labeled fibers branched extensively in the diencephalon, particularly along the third ventricle and in the septal-preoptic area. Sparse fiber labeling occurred caudal to the tuberal hypothalamus, even though these regions were close to the application site of the tracer. Labeled cerebrospinal-fluid-contracting cells were seen in the paraventricular region of the third ventricle. The results indicate that the avian neuronal system that projects to the median eminence and neural lobe occurs in diffuse clusters largely along the midline region of the hypothalamic septal-preoptic area. The paucity of fiber staining caudal to the tuberal hypothalamic region indicates that cells of these regions do not project to the median eminence/pituitary.

Afferent Pathways↗
PubMed1995

Variability of Doppler parameters in the healthy kidney: an anatomic-physiologic correlation.

Contradictory results have been obtained in classifying various renal diseases when trying to use the resistive index measured by duplex Doppler technique in renoparenchymal arteries. These measurements may have been influenced by the lack of standardization of the anatomic site at which the renoparenchymal artery is sampled. To elucidate this influence, we measured the resistive index, peak systolic velocity, end diastolic velocity, and pulsatility index in 120 healthy kidneys at three different positions of the renal vasculature. The resistive index at the level of the interlobar-arcuate arteries proved to be the parameter with the most consistent results and should be preferred in clinical applications.

Adult↗
PubMed1995

Age-related changes in resistive index following extracorporeal shock wave lithotripsy.

PURPOSE: Changes in intrarenal vascular resistance after extracorporeal shock wave lithotripsy (ESWL*) were studied with Doppler ultrasound techniques. MATERIALS AND METHODS: In 76 patients the resistive index was measured at an interlobar artery before and after ESWL in the treated and contralateral kidneys. The resistive index levels were compared to N-acetyl-beta-D-glucosaminidase levels in 40 patients. RESULTS: We found an age-related positive linear correlation between post-therapeutic resistive index increases and patient age. N-acetyl-beta-D-glucosaminidase levels were also elevated after ESWL but these elevations were not age-related. CONCLUSIONS: Elderly patients have a higher risk of post-ESWL renal tissue damage.

Acetylglucosaminidase↗
PubMed1994

Early exposure to androgens affects adult expression of alternative male types in tree lizards.

Males of many species exhibit strongly dimorphic reproductive behavior and morphology associated with alternative reproductive tactics. Little is known about the physiological control of these individual differences. The relative plasticity hypothesis proposes that such within-sex differences arise from either organizational or activational actions of sex steroid hormones depending on whether adults can switch tactics or not. This hypothesis predicts that differences between individuals in a species where adults cannot switch between tactics (are "fixed") should be organized by early actions of hormones. Three experiments explored the possible organizational role of testosterone (T) on the development of male alternatives in the tree lizard (Urosaurus ornatus), which has two fixed male morphs. Orange (O) males have a mostly orange throat fan (dewlap), are nonterritorial nomads, and are larger than orange-blue (OB) males which have an orange dewlap with a central blue patch and are territorial. In the first experiment intact males on the day of hatching were (1) sham-operated and implanted with empty capsules, (2) castrated, or (3) testosterone-implanted. As adults, the castration group had more O males than the control and the T-implanted group had more OB males than the control. Adult body size in castrated and T-implanted groups parallelled naturally occurring morph differences, but both were smaller than controls. A second experiment with a lower dose yielded similar results for dewlap type and growth. In a third experiment, intact males were given an empty capsule or a T-implant at 30 days posthatching. Again, the frequency of OB males in the T-implanted group was significantly greater than that in the empty implant group, indicating that either the critical period extends past Day 30 or there is no well-defined critical period. Together, these results support the hypothesis that the organizational action of T or one of its metabolites contributes to the differentiation of these within-sex differences.

Age Factors↗
PubMed1994

[Eosinophilic cellulitis (Wells syndrome) with involvement of para-articular muscles and fascia].

A 62-year-old woman developed eosinophilic cellulitis of her right arm, accompanied by systemic signs (fever, leucocytosis) and massive restriction of the motility of her right shoulder joint. Sonography and computed tomography revealed massive cutaneous and subcutaneous oedema, and accumulations of fluid around the deep muscular fasciae, interstices and (less severe) within the joint. High-dose systemic corticosteroid treatment led to rapid clearing of the skin lesions, and joint motility was restored several weeks later. This is the first case of eosinophilic cellulitis in which involvement of deep structures adjacent to joints has been demonstrated by modern imaging techniques.

Administration, Oral↗
PubMed1994

CT-guided stereolithography as a new tool in craniofacial surgery.

CT-guided stereolithography provides an acrylic model which exactly replicates the original structure. It allows optimal preoperative planning and intraoperative management. This application proved advantageous in surgical correction of a wide midline craniofacial cleft in a baby.

Face↗
PubMed1994

Skull of a 5,300-year-old mummy: reproduction and investigation with CT-guided stereolithography.

PURPOSE: In September 1991, a mummified corpse was discovered soon after it was released by the receding ice of the Similaun glacier in the Tyrolean Alps. This body proved to be an astonishingly well-preserved man from the late Neolithic Age or early Bronze Age. To preserve the fragile mummy, scientific investigations were required to be as noninvasive and nondestructive as possible. MATERIALS AND METHODS: A radiologic investigation that included conventional radiography, digital radiography, and whole-body computed tomography (CT) was performed from the CT data, the skull was duplicated by means of stereolithography. RESULTS: The copy of the prehistoric skull was validated by means of comparison of measurements obtained from the original CT images and from external physical measurements of the intact head of the mummy. CONCLUSION: The CT images, radiologic findings, and duplicated skull are expected to provide anthropologists and other interested scientists relatively accurate information without the need to handle the mummy, to expose it to the considerable risks of repeated partial thawing, or to perform invasive exploratory studies such as autopsy.

Animals↗