The effect of delayed visual feedback on telerobotic surgery.

BACKGROUND: Telerobotic surgery is ideally suited for remote applications in which the instrument control console is stationed separately from the end-effectors at the patient's bedside. However, if the distance between the console and the patient is great enough, a lag effect or latency between end-effector manipulation and the depicted image leads to alterations in movement patterns. The purpose of this study was to determine the effect of visual delay on surgical task performance. METHODS: At an endoscopic skill station, an analogue delay device was interposed between the surgical field and monitor to delay the transmission of visual information, thus mimicking the distance effect of data transmission. Three surgeons with similar laparoscopic experience participated in the laparoscopic knot tying portion of the study, and seven residents participated in the accuracy and dexterity tasks. The time to complete a single throw was recorded in seconds after adding consecutively increasingly time delay in 50 ms increments. Similar time delay increments were added for the accuracy and dexterity tasks, which involved passing a needle through two adjacent circles and passing a small cylinder through a larger one to reproduce two-handed coordination and spatial resolution. Data were presented as the median time to complete each task. RESULTS: For all three tasks, an incremental increase in time delay was associated with a significant (p < 0.001) increase in the time to complete the task. For dexterity, a statistically significant (p

The G protein alpha subunit (GP alpha1) is associated with the ER and the plasma membrane in meristematic cells of Arabidopsis and cauliflower.

Towards the elucidation of the cellular function(s) of GP alpha1, we have characterized its subcellular localization using immunofluorescence and cell fractionation. GP alpha1 is not present in nuclei or chloroplasts. It is a membrane-bound protein, and analysis of isolated endoplasmic and plasma membranes indicates a good correlation between GP alpha1 in both the plasma membrane and the ER compartment. Interestingly, these results may suggest more different functions for GP alpha1: it might be involved in transmission of extracellular signals across the plasma membrane and in the cytoplasm, and/or it may also be involved in regulating some aspects of the ER functions or membrane trafficking between both membranes.

Angiographic nephrectomy using iodinated contrast agent.

Diatrizoate meglumine and sodium (Renografin-76) was perfused in an obstructed renal artery in 13 dogs. Intense and prolonged accumulation of contrast agent ("contrast staining") was achieved in all animals. Repeat injection was frequently necessary to enhance staining. Renin output from the stained kidneys was lower than that from the opposite kidneys. Angiography at 14-18 weeks demonstrated a marked decrease in renal size in all dogs, with complete occlusion of the renal artery in two dogs. No collateral circulation was discerned. Grossly, all experimental kidneys were uniformly shrunken. Histologically, diffuse renal infarction was evident with coagulative necrosis. Contrast staining is an effective method for uniform destruction of renal tissue.

Bactericidal and endotoxin neutralizing activity of a peptide derived from Limulus antilipopolysaccharide factor.

BACKGROUND: Release of lipopolysaccharide (endotoxin, LPS) is a critical inciting event in the development of sepsis syndrome due to gram-negative bacteria, and mortality associated with this entity remains approximately 40%. Limulus anti-LPS factor (LALF) is a naturally occurring horseshoe crab derived protein that, unlike antibiotics, is both bactericidal for gram-negative bacteria and capable of neutralizing LPS. We hypothesized that a peptide derived from the active domain of LALF (LALF #28-54) would exhibit potent biologic activity similar to that of LALF itself and could potentially be useful as a therapeutic agent. METHODS: The effects of LALF, synthetic peptide LALF #28-54, polymyxin B (PmB), and a biologically inactive synthetic peptide were examined in several models. In vitro bactericidal activity was determined against Pseudomonas aeruginosa, and LPS-neutralizing capacity was determined via inhibition of LPS-induced tumor necrosis factor-alpha (TNF-alpha) secretion by RAW 264.7 cells. In vivo biologic activity was determined via pretreatment following which P aeruginosa endotoxemia or bacteremia was induced; serum TNF-alpha levels, bacterial clearance, and survival were assessed. RESULTS: LALF and LALF #28-54 exhibited potent in vitro bactericidal and LPS-neutralizing activity comparable to PmB (P <.01). However, although LALF #28-54 diminished systemic TNF-alpha production and aided bacterial clearance similar to that observed for LALF (P <.01), it did not provide significant protective capacity (P >.1). CONCLUSIONS: These data demonstrate that peptide LALF #28-54 retained the LPS-neutralizing and bactericidal biologic activity of LALF but failed to protect during overwhelming P aeruginosa bacteremia, perhaps due to short serum half-life.

Six years of surgical wound infection surveillance at a tertiary care center: review of the microbiologic and epidemiological aspects of 20,007 wounds.

HYPOTHESES: (1) Antibiotic restriction policies result in alteration of microbiologic features of surgical site infections (SSIs) and (2) reported SSI rates are underestimated when postdischarge surveillance is not included in SSI surveillance efforts. DESIGN: Retrospective analysis of prospectively collected SSI surveillance data. PATIENTS AND METHODS: We compared initial microbial isolates from SSIs between (1) January 1, 1993, and December 31, 1995, and (2) January; 1, 1996, and December 31, 1998. Antibiotic restriction policies were implemented at Fairview-University Medical Center, Minneapolis, Minn, on March 1, 1995. For the combined periods (January 1, 1993, to December 31, 1998), we determined SSI rates for 20007 operations according to the extent of bacterial contamination at surgery (wound class). Then, we analyzed SSI rates for 10559 of these operations (selected based on availability of Anesthesia Society of America score and type of procedure) using the surgical wound risk index (wound class, Anesthesia Society of America score, and length of operation). We categorized SSI rates by 17 procedures for comparison with SSI rates reported by 286 hospitals that contributed data confidentially and voluntarily to the National Nosocomial Infections Surveillance System in 1998. We compared SSI rates with and without postdischarge surveillance. RESULTS: Coagulase-negative staphylococcus and group D enterococcus were the 2 most frequent isolates before and after antibiotic restriction policies were implemented. Candida albicans isolates decreased from 7.9% (1993-1995) to 6.5% (1996-1998; P=.46). Methicillin-resistant Staphylococcus aureus (1.8% of isolates) and vancomycin-resistant enterococcus (2.4% of isolates) organisms were first identified between 1996 and 1998. Our SSI rates were 2.6% for class I wounds, 3.6% for class II wounds, and 10.5% for class III/IV wounds; 53.9% of SSIs were identified after hospital discharge. CONCLUSIONS: Antibiotic restriction policies did not alter the microbial spectrum of SSIs during the observation period. Reporting SSI rates in the absence of postdischarge surveillance dramatically underestimates actual SSI rates, especially in tertiary care hospitals that provide care for large populations of elderly and immunosuppressed patients.

Surgical treatment and long-term outcome of ferrets with bilateral adrenal tumors or adrenal hyperplasia: 56 cases (1994-1997).

OBJECTIVE: To determine signalment, clinical signs, concurrent diseases, response to surgical treatment, and long-term outcome of ferrets with bilateral adrenal tumors or adrenal hyperplasia. DESIGN: Retrospective study. ANIMALS: 56 ferrets with bilateral adrenal tumors or adrenal hyperplasia confirmed histologically following subtotal bilateral adrenalectomy. PROCEDURE: Medical records of all ferrets with bilateral adrenal tumors or hyperplasia examined between 1994 and 1997 were reviewed. Ferrets underwent a subtotal bilateral adrenalectomy or a unilateral adrenalectomy initially, followed by a unilateral subtotal adrenalectomy when tumors or hyperplasia later developed on the contralateral adrenal gland. A long-term follow-up of a minimum of 18 months after final adrenal gland surgery was obtained by examination of medical records and follow-up telephone conversations. RESULTS: Clinical signs of hyperadrenocorticism included bilaterally symmetric alopecia, return to male sexual behavior in castrated male ferrets, or swollen vulva in spayed female ferrets. Surgical treatment of bilateral adrenal disease by subtotal bilateral adrenalectomy (or unilateral adrenalectomy followed by contralateral unilateral subtotal adrenalectomy) was effective with a mortality rate of < 2%. Only 3 (5%) ferrets required glucocorticoid or mineralocorticoid replacement following subtotal bilateral adrenalectomy. Recurrence after bilateral adrenalectomy was 15% with a mean long-term follow-up period of 30 months. CONCLUSIONS AND CLINICAL RELEVANCE: Bilaterally symmetric alopecia, return to male sexual behavior in castrated male ferrets, or swollen vulva in spayed female ferrets are indicative of adrenal tumors or adrenal hyperplasia in ferrets. Surgical treatment of bilateral adrenal disease by subtotal bilateral adrenalectomy is effective, with a low rate of complications and postoperative recurrence rate.

Hip rating scales: a clinical analysis.

Thirty patients were graded both before and after total hip replacement according to several hip-rating scales and the results compared. This comparison shows that a scale which keeps the various parameters of pain, motion and function, separating rather than integrating them, is more useful to the surgeon. Subgrading the patients into A, B and C is essential for functional comparisons.

The treatment of pancreatic pseudocysts by laparoscopic drainage: endoluminal and lesser sac techniques.

A variety of approaches are now available to drain pancreatic pseudocysts (PP) when indicated. In addition to open surgery, endoscopic, laparoscopic, intra-luminal, and percutaneous techniques are available as therapeutic options to facilitate drainage of mature symptomatic PP. The laparoscopic lesser sac technique is appealing since it • relies on a secure stapled anastomosis, • provides an adequate sized cystgastrostomy to facilitate drainage, and • utilizes minimally invasive techniques to diminish operative morbidity and expedite return to normal activities. Short-term follow-up data suggest that this approach is feasible, effective and reproducible, Long-term studies demonstrating the efficacy of laparoscopic drainage of PP using the lesser sac technique are needed to validate these early favorable outcomes.

Mechanical properties and structure of the biological multilayered material system, Atractosteus spatula scales.

During recent decades, research on biological systems such as abalone shell and fish armor has revealed that these biological systems employ carefully arranged hierarchical multilayered structures to achieve properties of high strength, high ductility and light weight. Knowledge of such structures may enable pathways to design bio-inspired materials for various applications. This study was conducted to investigate the spatial distribution of structure, chemical composition and mechanical properties in mineralized fish scales of the species Atractosteus spatula. Microindentation tests were conducted, and cracking patterns and damage sites in the scales were examined to investigate the underlying protective mechanisms of fish scales under impact and penetration loads. A difference in nanomechanical properties was observed, with a thinner, stiffer and harder outer layer (indentation modulus ∼69 GPa and hardness ∼3.3 GPa) on a more compliant and thicker inner layer (indentation modulus ∼14.3 GPa and hardness ∼0.5 GPa). High-resolution scanning electron microscopy imaging of a fracture surface revealed that the outer layer contained oriented nanorods embedded in a matrix, and that the nanostructure of the inner layer contained fiber-like structures organized in a complex layered pattern. Damage patterns formed during microindentation show complex deformation mechanisms. Images of cracks identify growth through the outer layer, then deflection along the interface before growing and arresting in the inner layer. High-magnification images of the crack tip in the inner layer show void-linking and fiber-bridging exhibiting inelastic behavior. The observed difference in mechanical properties and unique nanostructures of different layers may have contributed to the resistance of fish scales to failure by impact and penetration loading.

Stability of the Giliberty bipolar hip: report of three cases.

The Giliberty Bipolar Hip Prosthesis consists of an unbonded acetabular cup which snap-fits over the head of the femoral prosthesis. Because of the free movement permitted at the cup-pelvic junction as well as at the snap-fit interface, there has been a great deal of concern over the potential for dislocation. Three patients in whom this unit was implanted sustained significant skeletal trauma subsequent to surgery. None of them dislocated. In each case the prosthetic head was known to be in a relatively vertical orientation with respect to the transverse axis of the pelvis prior to the injury. In 2 of the 3 cases radiographically identifiable movement of the cup was present before and after the injury. These observations suggest that the persistently mobile, vertically positioned unbonded cup remain stable despite the stress of significant trauma. It is probable that the potential for cup movement, even where on the X-ray it appears to have stopped, acts as a safety valve in absorbing force that might otherwise dislocate the hip or cause fractures of the femur or the pelvis.

Femoral stem failure and ectopic bone formation in total hip arthropalsty: four case reports.

In 4 cases of fracture of the femoral stem in total hip arthroplasty (THA), 3 were preceded by clinical and radiographic evidence of loosening and the last was not. Each developed a significant amount of ectopic bone. Stem failure in THA is a continuum progressing in some cases from ectopic bone formation and calcar resorption to stem loosening. An association between ectopic ossification and stem loosening is determined by grading the quantity of new bone not only by the amount but also by its spatial relationship with the implant. Observation on a large number of cases by the method of DeLee, Ferrari, and Charnley is required to prove or disprove the effect of ectopic bone on stem failure. In any case, patients who develop ectopic bone should be restricted in their activities.

Subluxation of the tibialis posterior, a complication of tarsal tunnel decompression: a case report.

In a 16-year-old girl, anterior subluxation of the posterior tibial tendon repeatedly occurred after release of the flexor retinaculum for tarsal tunnel syndrome. The symptoms resulting from this subluxation were more disabling than the original complaint. A reconstructive procedure eliminated the subluxation but did not cause recurrence of the tarsal tunnel syndrome. Though this complication is rare, it suggests that opening of the retinaculum for decompression of the tarsal tunnel should be done as far posteriorly as possible, so that the remaining retinaculum can act as a flap to prevent subsequent anterior subluxation of the tendon(s).

Clinical aspects and surgical treatment of hyperadrenocorticism in the domestic ferret: 94 cases (1994-1996).

The signalment, clinical findings, laboratory values, and histopathological results of 96 ferrets with signs (i.e., bilaterally symmetrical alopecia, return to male sexual behavior, or an enlarged vulva) suggestive of hyperadrenocorticism were evaluated retrospectively. Of these 96 ferrets, 94 (98%) were diagnosed with hyperadrenocorticism histologically. Treatment consisted of unilateral adrenalectomy for unilateral tumors (84%) and subtotal bilateral adrenalectomy for bilateral adrenal tumors (16%). The histopathological diagnosis included nodular hyperplasia (56%), adrenocortical carcinoma (26%), and adrenocortical adenoma (16%). Common concurrent diseases included splenomegaly (87%), islet-cell tumor (27%), and cardiomyopathy (10%).

Immunolocalization of the G protein alpha subunit encoded by the GPA1 gene in Arabidopsis.

Heterotrimeric GTP binding proteins (G proteins) are important signal transducers in lower eukaryotes and in animal cells. In plants, the occurrence of GTP binding proteins has been reported, but their biological function remains unclear. Two genes coding for G protein alpha subunits have been cloned: GPA1 in Arabidopsis and TGA1 in tomato. To gain some insights into the function of GPA1, we describe an extensive immunolocalization of GPalpha1, the gene product of GPA1, during Arabidopsis development. Our results show that the GPalpha1 is present through all stages of development and in all organs examined, with the exception of mature seeds. It is expressed in roots, floral stem, rosette leaves, cauline leaves, flowers, and seed pods. Interestingly, the level of GPalpha1 protein is higher in immature organs than in mature organs. GPalpha1 is present at a high level in the root meristem and elongation zone, in the shoot and floral meristems, and in the leaf primordium and floral organ (sepal, petal, stamen, and gynoecium) primordia. During flower development, dividing microspores, but not mature pollen, show high levels of GPalpha1. During pollination, GPalpha1 is present in the growing pollen tubes. The protein is also present in nectaries and developing ovules and, after fertilization, in developing embryos. In mature tissue, GPalpha1 is preferentially found in the vascular system but is also present in other cell types. The complexity of the GPalpha1 localization pattern suggests that GPalpha1 might be involved in different signaling pathways depending on the developmental stage.

Insulinoma in the ferret: clinical findings and treatment comparison of 66 cases.

The clinical signs and surgical findings were reported for 66 ferrets with insulinomas confirmed histologically. All of the ferrets were treated with one of three modalities, and disease-free intervals and survival times were gathered to determine the most effective treatment. The three treatment groups included 10 ferrets treated medically, 27 ferrets treated with pancreatic nodulectomy, and 29 ferrets treated with pancreatic nodulectomy combined with a partial pancreatectomy. The mean disease-free intervals for each group were 22, 234, and 365 days, respectively. The mean survival times for each group were 186, 456, and 668 days, respectively. Based upon the data, recommendations were made for treating insulinoma in the ferret.

Isolation of cDNAs encoding guanine nucleotide-binding protein beta-subunit homologues from maize (ZGB1) and Arabidopsis (AGB1).

We have isolated cDNAs from maize (ZGB1) and Arabidopsis (AGB1) encoding proteins homologous to beta subunits of guanine nucleotide-binding protein (G protein). The predicted ZGB1 and AGB1 gene products are 76% identical to each other and 41% or more identical to animal G protein beta subunits. Both predicted proteins contain seven repeats of the so-called "WD-40" motif, where WD is Trp-Asp. RNA blot analysis indicates that ZGB1 mRNA is present in the root, leaf, and tassel and that AGB1 mRNA is expressed in the root, leaf, and flower. DNA blot hybridizations indicate that maize and Arabidopsis genomes contain no other genes that are highly similar to ZGB1 and AGB1, respectively, suggesting that the newly isolated G protein beta-subunit homologues are likely to have unique functions. Furthermore, these G protein beta-subunit homologues are conserved among other plant species and may play important role(s) in plant signaling.

The role of epidural cortisone injection in the treatment of diskogenic low back pain.

Primary treatment by epidural injection of cortisone in patients suffering from characteristic diskogenic disease was helpful in 82% of patients. However, when given after three months of back pain, after previous laminectomies, and in patients actually suffering from an unstable spine which required fusion, epidural injections were of little value. No complications resulted from the injection and there was no compelling evidence to indicate that the placement of the needle by radiologic means is necessary. Because of these benefits and the fact that all of the patients were candidates for laminectomy, the use of this injection prior to surgery should be considered. The number of injections that may reasonably be given, the degree to which the patient should become asymptomatic, and the period of time during which relief continues remain to be clarified by a larger and more sustained study.