GAD65Cre Drives Reporter Expression in Multiple Taste Cell Types

In taste buds, Type I cells represent the majority of cells (50-60%) and primarily have a glial-like function in taste buds. However, recent studies suggest that they have additional sensory and signaling functions including amiloride-sensitive salt transduction, oxytocin modulation of taste, and substance P mediated GABA release. Nonetheless, the overall function of Type I cells in transduction and signaling remains unclear, primarily because of the lack of a reliable reporter for this cell type. GAD65 expression is specific to Type I taste cells and GAD65 has been used as a Cre driver to study Type I cells in salt taste transduction. To test the specificity of transgene-driven expression, we crossed GAD65Cre mice with floxed tdTomato and Channelrhodopsin (ChR2) lines and examined the progeny with immunochemistry, chorda tympani recording, and calcium imaging. We report that while many tdTomato+ taste cells express NTPDase2, a specific marker of Type I cells, we see some expression of tdTomato in both Gustducin and SNAP25-positive taste cells. We also see ChR2 in cells just outside the fungiform taste buds. Chorda tympani recordings in the GAD65Cre/ChR2 mice show large responses to blue light. Furthermore, several isolated tdTomato-positive taste cells responded to KCl depolarization with increases in intracellular calcium, indicating the presence of voltage-gated calcium channels. Taken together, these data suggest that GAD65Cre mice drive expression in multiple taste cell types and thus cannot be considered a reliable reporter of Type I cell function.

Expression of Bitter Taste Receptors and Solitary Chemosensory Cell Markers in the Human Sinonasal Cavity

Some bitter taste receptors (TAS2R gene products) are expressed in the human sinonasal cavity and may function to detect airborne irritants. The expression of all 25 human bitter taste receptors and their location within the upper airway is not yet clear. The aim of this study is to characterize the presence and distribution of TAS2R transcripts and solitary chemosensory cells (SCCs) in different locations of the human sinonasal cavity. Biopsies were obtained from human subjects at up to 4 different sinonasal anatomic sites. PCR, microarray, and qRT-PCR were used to examine gene transcript expression. The 25 human bitter taste receptors as well as the sweet/umami receptor subunit, TAS1R3, and canonical taste signaling effectors are expressed in sinonasal tissue. All 25 human bitter taste receptors are expressed in the human upper airway, and expression of these gene products was higher in the ethmoid sinus than nasal cavity locations. Fluorescent in situ hybridization demonstrates that epithelial TRPM5 and TAS2R38 are expressed in a rare cell population compared with multiciliated cells, and at times, consistent with SCC morphology. Secondary analysis of published human sinus single-cell RNAseq data did not uncover TAS2R or canonical taste transduction transcripts in multiciliated cells. These findings indicate that the sinus has higher expression of SCC markers than the nasal cavity in chronic rhinosinusitis patients, comprising a rare cell type. Biopsies obtained from the ethmoid sinus may serve as the best location for study of human upper airway taste receptors and SCCs.

A2ML1 and otitis media: novel variants, differential expression, and relevant pathways

A genetic basis for otitis media is established, however, the role of rare variants in disease etiology is largely unknown. Previously a duplication variant within A2ML1 was identified as a significant risk factor for otitis media in an indigenous Filipino population and in US children. In this report exome and Sanger sequencing was performed using DNA samples from the indigenous Filipino population, Filipino cochlear implantees, US probands, Finnish, and Pakistani families with otitis media. Sixteen novel, damaging A2ML1 variants identified in otitis media patients were rare or low-frequency in population-matched controls. In the indigenous population, both gingivitis and A2ML1 variants including the known duplication variant and the novel splice variant c.4061 + 1 G>C were independently associated with otitis media. Sequencing of salivary RNA samples from indigenous Filipinos demonstrated lower A2ML1 expression according to the carriage of A2ML1 variants. Sequencing of additional salivary RNA samples from US patients with otitis media revealed differentially expressed genes that are highly correlated with A2ML1 expression levels. In particular, RND3 is upregulated in both A2ML1 variant carriers and high-A2ML1 expressors. These findings support a role for A2ML1 in keratinocyte differentiation within the middle ear as part of otitis media pathology and the potential application of ROCK inhibition in otitis media.

Airborne laser-guided imaging spectroscopy to map forest trait diversity and guide conservation

Functional biogeography may bridge a gap between field-based biodiversity information and satellite-based Earth system studies, thereby supporting conservation plans to protect more species and their contributions to ecosystem functioning. We used airborne laser-guided imaging spectroscopy with environmental modeling to derive large-scale, multivariate forest canopy functional trait maps of the Peruvian Andes-to-Amazon biodiversity hotspot. Seven mapped canopy traits revealed functional variation in a geospatial pattern explained by geology, topography, hydrology, and climate. Clustering of canopy traits yielded a map of forest beta functional diversity for land-use analysis. Up to 53% of each mapped, functionally distinct forest presents an opportunity for new conservation action. Mapping functional diversity advances our understanding of the biosphere to conserve more biodiversity in the face of land use and climate change.

RNA sequencing and pathway analysis identify tumor necrosis factor alpha driven small proline-rich protein dysregulation in chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) is a heterogeneous inflammatory disorder in which many pathways contribute to end-organ disease. Small proline-rich proteins (SPRR) are polypeptides that have recently been shown to contribute to epithelial biomechanical properties relevant in T-helper type 2 inflammation. There is evidence that genetic polymorphism in SPRR genes may predict the development of asthma in children with atopy and, correlatively, that expression of SPRRs is increased under allergic conditions, which leads to epithelial barrier dysfunction in atopic disease.

METHODS

RNAs from uncinate tissue specimens from patients with CRS and control subjects were compared by RNA sequencing by using Ingenuity Pathway Analysis (n = 4 each), and quantitative polymerase chain reaction (PCR) (n = 15). A separate cohort of archived sinus tissue was examined by immunohistochemistry (n = 19).

RESULTS

A statistically significant increase of SPRR expression in CRS sinus tissue was identified that was not a result of atopic presence. SPRR1 and SPRR2A expressions were markedly increased in patients with CRS (p < 0.01) on RNA sequencing, with confirmation by using real-time PCR. Immunohistochemistry of archived surgical samples demonstrated staining of SPRR proteins within squamous epithelium of both groups. Pathway analysis indicated tumor necrosis factor (TNF) alpha as a master regulator of the SPRR gene products.

CONCLUSION

Expression of SPRR1 and of SPRR2A is increased in mucosal samples from patients with CRS and appeared as a downstream result of TNF alpha modulation, which possibly resulted in epithelial barrier dysfunction.

FGF21 Mediates Endocrine Control of Simple Sugar Intake and Sweet Taste Preference by the Liver

The liver is an important integrator of nutrient metabolism, yet no liver-derived factors regulating nutrient preference or carbohydrate appetite have been identified. Here we show that the liver regulates carbohydrate intake through production of the hepatokine fibroblast growth factor 21 (FGF21), which markedly suppresses consumption of simple sugars, but not complex carbohydrates, proteins, or lipids. Genetic loss of FGF21 in mice increases sucrose consumption, whereas acute administration or overexpression of FGF21 suppresses the intake of both sugar and non-caloric sweeteners. FGF21 does not affect chorda tympani nerve responses to sweet tastants, instead reducing sweet-seeking behavior and meal size via neurons in the hypothalamus. This liver-to-brain hormonal axis likely represents a negative feedback loop as hepatic FGF21 production is elevated by sucrose ingestion. We conclude that the liver functions to regulate macronutrient-specific intake by producing an endocrine satiety signal that acts centrally to suppress the intake of "sweets."

Mice Lacking Pannexin 1 Release ATP and Respond Normally to All Taste Qualities

Adenosine triphosphate (ATP) is required for the transmission of all taste qualities from taste cells to afferent nerve fibers. ATP is released from Type II taste cells by a nonvesicular mechanism and activates purinergic receptors containing P2X2 and P2X3 on nerve fibers. Several ATP release channels are expressed in taste cells including CALHM1, Pannexin 1, Connexin 30, and Connexin 43, but whether all are involved in ATP release is not clear. We have used a global Pannexin 1 knock out (Panx1 KO) mouse in a series of in vitro and in vivo experiments. Our results confirm that Panx1 channels are absent in taste buds of the knockout mice and that other known ATP release channels are not upregulated. Using a luciferin/luciferase assay, we show that circumvallate taste buds from Panx1 KO mice normally release ATP upon taste stimulation compared with wild type (WT) mice. Gustatory nerve recordings in response to various tastants applied to the tongue and brief-access behavioral testing with SC45647 also show no difference between Panx1 KO and WT. These results confirm that Panx1 is not required for the taste evoked release of ATP or for neural and behavioral responses to taste stimuli.

Postsynaptic P2X3-containing receptors in gustatory nerve fibres mediate responses to all taste qualities in mice

Taste buds release ATP to activate ionotropic purinoceptors composed of P2X2 and P2X3 subunits, present on the taste nerves. Mice with genetic deletion of P2X2 and P2X3 receptors (double knockout mice) lack responses to all taste stimuli presumably due to the absence of ATP-gated receptors on the afferent nerves. Recent experiments on the double knockout mice showed, however, that their taste buds fail to release ATP, suggesting the possibility of pleiotropic deficits in these global knockouts. To test further the role of postsynaptic P2X receptors in afferent signalling, we used AF-353, a selective antagonist of P2X3-containing receptors to inhibit the receptors acutely during taste nerve recording and behaviour. The specificity of AF-353 for P2X3-containing receptors was tested by recording Ca(2+) transients to exogenously applied ATP in fura-2 loaded isolated geniculate ganglion neurons from wild-type and P2X3 knockout mice. ATP responses were completely inhibited by 10 μm or 100 μm AF-353, but neither concentration blocked responses in P2X3 single knockout mice wherein the ganglion cells express only P2X2-containing receptors. Furthermore, AF-353 had no effect on taste-evoked ATP release from taste buds. In wild-type mice, i.p. injection of AF-353 or simple application of the drug directly to the tongue, inhibited taste nerve responses to all taste qualities in a dose-dependent fashion. A brief access behavioural assay confirmed the electrophysiological results and showed that preference for a synthetic sweetener, SC-45647, was abolished following i.p. injection of AF-353. These data indicate that activation of P2X3-containing receptors is required for transmission of all taste qualities.

Solitary chemosensory cells and bitter taste receptor signaling in human sinonasal mucosa

BACKGROUND

Solitary chemosensory cells (SCCs) are specialized cells in the respiratory epithelium that respond to noxious chemicals including bacterial signaling molecules. SCCs express components of bitter taste transduction including the taste receptor type 2 (TAS2R) bitter taste receptors and downstream signaling effectors: α-Gustducin, phospholipase Cβ2 (PLCβ2), and transient receptor potential cation channel subfamily M member 5 (TRPM5). When activated, SCCs evoke neurogenic reflexes, resulting in local inflammation. The purpose of this study was to test for the presence SCCs in human sinonasal epithelium, and to test for a correlation with inflammatory disease processes such as allergic rhinitis and chronic rhinosinusitis.

METHODS

Patient demographics and biopsies of human sinonasal mucosa were obtained from control patients (n = 7) and those with allergic rhinitis and/or chronic rhinosinusitis (n = 15). Reverse transcription polymerase chain reaction (RT-PCR), quantitative PCR (qPCR), and immunohistochemistry were used to determine whether expression of signaling effectors was altered in diseased patients.

RESULTS

RT-PCR demonstrated that bitter taste receptors TAS2R4, TAS2R14, and TAS2R46, and downstream signaling effectors α-Gustducin, PLCβ2, and TRPM5 are expressed in the inferior turbinate, middle turbinate, septum, and uncinate of both control and diseased patients. PLCβ2/TRPM5-immunoreactive SCCs were identified in the sinonasal mucosa of both control and diseased patients. qPCR showed similar expression of α-Gustducin and TRPM5 in the uncinate process of control and diseased groups, and there was no correlation between level of expression and 22-item Sino-Nasal Outcomes Test (SNOT-22) or pain scores.

CONCLUSION

SCCs are present in human sinonasal mucosa in functionally relevant areas. Expression level of signaling effectors was similar in control and diseased patients and did not correlate with measures of pain and inflammation. Further study into these pathways may provide insight into nasal inflammatory diseases and may offer potential therapeutic targets.

Evidence for a role of glutamate as an efferent transmitter in taste buds

Background

Glutamate has been proposed as a transmitter in the peripheral taste system in addition to its well-documented role as an umami taste stimulus. Evidence for a role as a transmitter includes the presence of ionotropic glutamate receptors in nerve fibers and taste cells, as well as the expression of the glutamate transporter GLAST in Type I taste cells. However, the source and targets of glutamate in lingual tissue are unclear. In the present study, we used molecular, physiological and immunohistochemical methods to investigate the origin of glutamate as well as the targeted receptors in taste buds.

Results

Using molecular and immunohistochemical techniques, we show that the vesicular transporters for glutamate, VGLUT 1 and 2, but not VGLUT3, are expressed in the nerve fibers surrounding taste buds but likely not in taste cells themselves. Further, we show that P2X2, a specific marker for gustatory but not trigeminal fibers, co-localizes with VGLUT2, suggesting the VGLUT-expressing nerve fibers are of gustatory origin. Calcium imaging indicates that GAD67-GFP Type III taste cells, but not T1R3-GFP Type II cells, respond to glutamate at concentrations expected for a glutamate transmitter, and further, that these responses are partially blocked by NBQX, a specific AMPA/Kainate receptor antagonist. RT-PCR and immunohistochemistry confirm the presence of the Kainate receptor GluR7 in Type III taste cells, suggesting it may be a target of glutamate released from gustatory nerve fibers.

Conclusions

Taken together, the results suggest that glutamate may be released from gustatory nerve fibers using a vesicular mechanism to modulate Type III taste cells via GluR7.

Effects of surgical or banding castration on stress responses and behaviour of bulls

OBJECTIVE

To compare the effects of surgical and latex banding methods of castration in 14- and 9-month-old bulls.

DESIGN

Two randomised, controlled experiments.

PROCEDURE

In Experiment 1, following administration of local anaesthetic, 14-month-old bulls were castrated by either surgical or banding methods, or left entire. Behavioural, plasma cortisol, plasma haptoglobin and bodyweight responses were recorded. A group of steers from the same mob was used as an additional comparison for bodyweight data. In Experiment 2, following administration of local anaesthetic, 9-month-old bulls were castrated by either surgical or banding methods and cortisol, haptoglobin and bodyweight responses were recorded. Entire bulls from the same group were used as an additional comparison for bodyweight data.

RESULTS

In Experiment 1, surgical castrates exhibited more leg stamping and tail swishing than banded or entire animals in the hours after castration. Surgical castrates in both experiments also showed an increase in plasma haptoglobin, which resolved after 4 days. Plasma cortisol was generally not affected by castration. Surgical castrates grew more slowly than entire bulls, but faster than banded animals, in the 56 days after treatment. In Experiment 1, after 56 days, the bodyweights of surgical and banded castrates were not different from the bodyweights of the steers. Fourteen-month-old banded cattle developed persistent wounds above the latex band which remained for several weeks after scrotal dehiscence, but this did not occur in the 9-month-old animals.

CONCLUSION

The banding procedure produced fewer acute effects, but a greater suppression of growth than surgical castration and induced prolonged wound formation in the older age group, suggesting that this procedure may not be as suitable for yearling cattle.

A national survey of policies on disclosure of conflicts of interest in biomedical research

BACKGROUND

Conflicts of interest pose a threat to the integrity of scientific research. The current regulations of the U.S. Public Health Service and the National Science Foundation require that medical schools and other research institutions report the existence of conflicts of interest to the funding agency but allow the institutions to manage conflicts internally. The regulations do not specify how to do so.

METHODS

We surveyed all medical schools (127) and other research institutions (170) that received more than $5 million in total grants annually from the National Institutes of Health or the National Science Foundation; 48 journals in basic science and clinical medicine; and 17 federal agencies in order to analyze their policies on conflicts of interest.

RESULTS

Of the 297 institutions, 250 (84 percent) responded by March 2000, as did 47 of the 48 journals and 16 of the 17 federal agencies. Fifteen of the 250 institutions (6 percent)--5 medical schools and 10 other research institutions--reported that they had no policy on conflicts of interest. Among the institutions that had policies, there was marked variation in the definition and management of conflicts. Ninety-one percent had policies that adhered to the federal threshold for disclosure ($10,000 in annual income or equity in a relevant company or 5 percent ownership), and 9 percent had policies that exceeded the federal guidelines. Only 8 percent had policies requiring disclosure to funding agencies, only 7 percent had such policies regarding journals, and only 1 percent had policies requiring the disclosure of information to the relevant institutional review boards or to research subjects. Twenty journals (43 percent) reported that they had policies requiring disclosure of conflicts of interest. Only four federal agencies had policies that explicitly addressed conflicts of interest in extramural research, and all but one of the agencies relied primarily on institutional discretion.

CONCLUSIONS

There is substantial variation among policies on conflicts of interest at medical schools and other research institutions. This variation, combined with the fact that many scientific journals and funding agencies do not require disclosure of conflicts of interest, suggests that the current standards may not be adequate to maintain a high level of scientific integrity.

E7-transduced human breast epithelial cells show partial differentiation in three-dimensional culture

Disruption of the retinoblastoma (RB) tumor suppressor pathway is a common and important event in breast carcinogenesis. To examine the role of the retinoblastoma protein (pRB) in this process, we created human mammary epithelial cells (HMEC) deficient for pRB by infecting primary outgrowth from breast organoids with the human papillomavirus type 16 (HPV16) E7 gene. HPV16 E7 binds to and inactivates pRB and also causes a significant down-regulation of the protein. Culturing normal HMEC in a reconstituted basement membrane (rBM) provides a correct environment and signaling cues for the formation of differentiated, acini-like structures. When cultured in this rBM, HMEC+E7 were found to respond morphologically as normal HMEC and form acinar structures. In contrast to normal HMEC, many of the cells within the HMEC+E7 structures were not growth arrested, as determined by a 5-bromo-2'-deoxyuridine incorporation assay. pRB deficiency did not affect polarization of these structures, as indicated by the normal localization of the cell-cell adhesion marker E-cadherin and the basal deposition of a collagen IV membrane. However, in HMEC+E7 acini, we were unable to detect by immunofluorescence microscopy the milk protein lactoferrin or cytokeratin 19, both markers of differentiation expressed in the normal HMEC structures. These data suggest that loss of RB in vivo would compromise differentiation, predisposing these cells to future tumor-promoting actions.

Comparative evaluation of two models for estimating sample sizes for tests on trends across repeated measurements

Two equations for calculating sample sizes that are required for power in testing differences in rates of change in repeated measurement designs have been presented by different authors. One equation provides support for the conclusion that increased frequency of measurements across a treatment period of fixed duration enhances power of the tests. The other equation supports the counterintuitive conclusion that increased frequency of measurements actually tends to decrease power in the presence of realistic serial dependencies in the data. Monte Carlo methods confirm that the equation providing support for the latter conclusion is accurate, whereas the alternative equation tends to underestimate sample sizes required for power in testing differences in slopes of regression lines fitted to changes in the repeated measurements across time when symmetry is absent from the covariance structure.

Behavioral and pharmacologic approaches to smoking cessation

Cigarette smoking continues to be the single, most preventable cause of death and disability in the United States. For individuals who have cancer, continuing to smoke negatively impacts their treatment, survival, and risk for second primary tumors. This review of behavioral and pharmacological approaches to smoking cessation focuses on the recent comprehensive review of cessation interventions by the Agency for Health Care Policy and Research (AHCPR), as well as on new developments in the field. An intervention model is outlined that provides oncologists with a brief and easily implemented method of systematically treating patients who smoke. By assessing patient smoking status, advising smoking patients to quit, and proactively assisting their patients in quitting, oncologists can significantly influence patient health and fulfill their professional and ethical responsibility to address this life-threatening behavior.

Spontaneous closure of selected iatrogenic pseudoaneurysms and arteriovenous fistulae

PURPOSE

We report our approach to the management of postcatheterization femoral artery pseudoaneurysms and arteriovenous fistulae in an attempt to determine the frequency of spontaneous resolution of selected lesions.

METHODS

We studied 196 pseudoaneurysms, 81 arteriovenous fistulae, and 9 combined lesions that were identified by duplex scan. Indications for immediate surgical repair included pseudoaneurysm greater than 3 cm, enlarging hematoma, pain, groin infection, nerve compression, limb ischemia, concomitant surgical procedure, and patient refusal or inability to comply with follow-up. All other lesions were observed.

RESULTS

One hundred thirty-nine patients underwent prompt surgical repair, and 147 patients were initially managed without operation. There were no limb-threatening complications associated with nonoperative management in this subset of patients. Eighty-six percent of the lesions being observed resolved spontaneously within a mean of 23 days, whereas 14% required surgical closure for a variety of reasons (at a mean of 111 days after the initial diagnosis). There was no statistically significant difference in the rate of spontaneous pseudoaneurysm closure (89%) as opposed to fistulae (81%) (p < 0.17). By life-table analysis, 90% of selected pseudoaneurysms had resolved by 2 months. Patients selected for observation underwent an average of 2.6 duplex scans per patient versus 1.4 scans per patient for those treated with immediate surgery (p < 0.01).

CONCLUSION

The natural history of stable pseudoaneurysms and arteriovenous fistulae is benign and frequently results in spontaneous resolution, which allows properly selected patients to be managed without operation.

Objective tinnitus resulting from internal carotid artery stenosis

Objective tinnitus represents sound wave energy that, by definition, may be heard or recorded by an examiner. It may occur as a result of either muscular contraction or turbulent blood flow. We report two cases of vascular objective tinnitus resulting from internal carotid artery stenosis. The first patient, a 74-year-old man, underwent ligation of the right internal carotid artery because of the distal extent of atherosclerosis. The second patient, a 75-year-old man, underwent a right carotid endarterectomy. Both patients noted complete relief of their tinnitus. The spectrum of vascular causes and treatment options are reviewed.

Revascularization of the solitary kidney: a challenging problem in a high risk population

BACKGROUND

Patients with significant atherosclerotic stenosis involving the artery to a solitary functioning kidney present a clinical challenge.

METHODS

From August 1987 through August 1995, 35 of these patients (average age, 68.4 +/- 6.9 years) were treated. Comorbid conditions included previous myocardial infarction in 23% of the patients, congestive heart failure (CHF) in 34%, chronic obstructive pulmonary disease in 20%, and diabetes in 20%. The average creatinine level of the patients was 2.5 +/- 1.5 mg/dl. Indications for revascularization were hypertension in 86%, hypertensive crisis with CHF in 17%, and renal insufficiency in 69%. Procedures performed included 19 extra-anatomic bypasses, 8 concomitant with infrarenal aortic reconstruction and 2 concomitant with thoracoabdominal aortic aneurysm repair; 1 visceral segment endarterectomy; 1 renal artery endarterectomy with reimplantation; I superior mesenteric to renal artery bypass; 1 aortorenal bypass; and 2 percutaneous angioplasties with staged nephrectomies.

RESULTS

At discharge, 91% of patients had stable or improved renal function with an average creatinine level of 1.7 +/- 0.8 mg/dl. Hypertension was cured or improved in 85%. Perioperative mortality was 6%, and major morbidity was 43%, including the need for permanent (9%) and temporary (9%) dialysis, respiratory insufficiency (18%), two early reoperations, six cardiac complications, one case of gastrointestinal bleeding, and one stroke. In the follow-up period (mean duration, 39.2 months), survival has been 73%, and no additional patients have required dialysis.

CONCLUSIONS

Although significant perioperative morbidity exists in this high risk population, the long-term preservation of renal function and improvement in hypertension make solitary renal revascularization worthwhile.

Intraoperative salvage in patients undergoing elective abdominal aortic aneurysm repair: an analysis of cost and benefit

PURPOSE

Although autologous blood procurement has become a standard of care in elective surgery, recent studies have questioned its cost-effectiveness. We therefore reviewed our 3-year experience with intraoperative cell salvage in patients who underwent elective abdominal aortic aneurysm repair.

METHODS

A 3-year retrospective chart review of elective abdominal aortic aneurysm (infrarenal and suprarenal) repair was performed. Transthoracic repairs were excluded.

RESULTS

Estimated blood lost was 1748 +/- 1236 ml, or 35% of baseline blood volume (5012 +/- 689 ml). Overall, 164 (89%) received red blood cell (RBC) transfusions (3.5 +/- 2.0 U/patient). The cost per patient for cell salvage was $315 +/- $97, representing 31% of all RBC costs and 24% of total blood component costs. Mean salvage volume infused was 578 +/- 600 ml; at a mean hematocrit level of 55.7% the RBC volume infused from salvage during surgery was 313 +/- 328 ml (representing 27% of total RBC volume lost during the hospital stay). This mean RBC volume salvaged represented the equivalent of 1.6 blood bank RBC units. The mean blood bank costs saved by using cell salvage was $248, or 79% of the $315 actually spent for salvage. We found no decrease in percentage of patients undergoing transfusion until salvage volumes that were infused exceeded 750 ml, or the equivalent of two blood bank units; all of these patients who benefitted had estimated blood lost > or = 1000 ml.

CONCLUSIONS

We conclude that use of intraoperative cell salvage was most beneficial for patients who had estimated blood loss greater than or equal to 1000 ml and cell salvage volumes infused greater than or equal to 750 ml. Patients who are estimated to lose less than 1000 ml receive little benefit yet incur substantial costs from intraoperative cell salvage.

Arachidonic acid metabolism in intestinal hypothermic preservation injury

The effect of hypothermic intestinal ischemia and short-term reperfusion on mucosal arachidonic acid metabolism was studied in a dog model of intestinal preservation injury. Canine intestinal segments were flushed with cold Collins solution, cold stored (4 degrees C) for either 24 or 48 h, and subsequently reperfused in the donor for 1 h. Samples of intestinal mucosa obtained before ischemia, after the ischemia period, and after the reperfusion period were placed into tissue culture, and arachidonic acid metabolites were measured in the tissue incubation media. Prostaglandin E2 (PGE2) and prostacyclin (PGI2) production significantly increased after 24 h of cold ischemia and after 1 h of reperfusion, respectively. Intestines cold stored for 48 h and after 1 h of reperfusion produced significantly elevated quantities of thromboxane B2, PGI2, PGE2, and leukotriene B4, relative to the production rates from nonischemic control tissue or tissue subjected to 48 h of hypothermic ischemia without reperfusion. Mucosal production of thiol ether leukotrienes (LTC4, LTD4, LTE4) was not altered by ischemia or reperfusion at any time of cold ischemia. The synthesis of the lipoxygenase product 12-hydroxyeicosatetraenoic acid (12-HETE) was not altered by hypothermic ischemia or reperfusion, but this arachidonate metabolite was produced by small intestinal mucosa in the greatest quantities. Specifically, nanogram quantities of 12-HETE were produced by intestinal mucosa compared to picogram quantities of the other metabolites measured. Significant synthesis of the delta lactone derivative of 5-hydroxyeicosatetraenoic acid was detected by HPLC in many tissue samples undergoing 48 h of ischemia and reperfusion, relative to nonischemic tissue samples. In conclusion, significant increases in arachidonate cyclooxygenase and lipoxygenase metabolites have been identified in intestinal mucosa subjected to long-term hypothermic ischemia and short-term reperfusion. Synthesis of these products increases with the duration of cold ischemia and may play a role in intestinal preservation injury.

Femoropopliteal bypass for claudication: vein vs. PTFE

The vascular graft of choice for femoropopliteal bypass in patients with intolerable claudication is controversial. We retrospectively reviewed our experience with 239 patients suffering from claudication secondary to superficial femoral artery obstruction. Femoropopliteal reconstruction was performed with saphenous vein to the below-knee popliteal artery in 66 patients (BK-vein). Polytetrafluoroethylene (PTFE) was used in 128 patients as a bypass graft to the above-knee popliteal artery (AK-PTFE) and 45 patients had a PTFE graft to the below-knee popliteal artery (BK-PTFE). All patients were enrolled in a postoperative graft surveillance program with graft revision when appropriate. There was one perioperative death (0.4%). Primary patency at 5 years for AK-PTFE, BK-PTFE, and BK-vein was 58.0%, and 60.3%, respectively, and was not significantly different among the graft groups. Graft revision for failed/failing grafts resulted in 5-year secondary patency rates of 79.2% (AK-PTFE), 73.3% (BK-PTFE), and 74.4% (BK-vein). These secondary patency rates were not statistically different. Eventual conversion to a vein graft in patients initially treated with PTFE maximized patency in the femoropopliteal segment with 5-year patency rates of 84.6% and 93.0% for the AK-PTFE and BK-PTFE graft groups, respectively. Major leg amputation was necessary during the entire course of the study in eight (3.3%) patients. We conclude that long-term patency rates for femoropopliteal bypass in patients with intolerable claudication are similar for PTFE and autologous saphenous vein grafts.

Donor-specific transfusions have long-term beneficial effects for human renal allografts

From April, 1980 to November, 1988, 163 one or two haplotype-mismatch living related (LR) or living unrelated (LUR) potential renal transplant recipients received three 200 ml aliquots of donor specific transfusion (DST) at biweekly intervals with concomitant azathioprine (2 mg/kg/day). Following transplantation, only prednisone and azathioprine were given for immunosuppression. The results for the DST group are compared with those for HLA identical living recipients (57 patients) transplanted during this same interval (1980-1988). Comparison is also made with a group of one or two haplotype-mismatched living donor recipients (54 patients) not treated with DST but with triple drug therapy (prednisone, azathioprine, cyclosporine) and antithymocyte globulin (ATG) or OKT-3 induction. Permanent T cell crossmatch sensitization occurred in 11 of 163 patients (7%). Successful DST donor transplants were performed between 121 one HLA haplotype-mismatched, 14 two HLA haplotype-mismatched LR, and 7 two haplotype-mismatched LUR pairs. Actual one- and five-year graft survivals were 94%, 100%, 100%, and 72%, 85%, and 71%, respectively, for these three subgroups of DST treated patients. The graft survival for all DST pretreated recipients at one, five, and ten years was comparable to the HLA-identical group (94%, 79%, 64% vs. 91%, 80% and 77%). At a mean follow-up of 10 1/2 years, 54% (80 patients) of the entire group of 147 patients transplanted after DST have functioning transplants with a mean serum creatinine of 1.7 mg/dl. Fifteen percent of DST patients (21 patients) died with a functioning graft 2 to 132 months after transplantation, 26% (37 patients) rejected the DST graft after 1 to 128 months, and 6% (9 patients) were lost for nonimmunological reasons. No lymphoproliferative disease developed in the DST group and the incidence of cytomegalovirus sepsis was only 2% (3 patients). The long-term beneficial effects of DST on renal allograft survival and function and the lower incidence of the complications of nonspecific immunosuppression should encourage increased utilization of DST in renal transplantation.

Limb salvage and patency after aortic reconstruction in younger patients

PURPOSE

The purpose of this report was to compare patient characteristics, treatment, and outcome in younger and older patients with aortoiliac occlusive disease.

METHODS

The medical records of 56 patients < or = 50 years of age (Group < or = 50) were retrospectively reviewed and compared to the records of 128 patients > or = 60 years of age (Group > or = 60). All patients were examined and treated between April 1987 and April 1994. Postoperatively, they were enrolled in a vascular laboratory surveillance program to serially monitor the status of the vascular reconstruction. Follow-up averaged more than 3 years in both groups and was available on greater than 90% of patients.

RESULTS

Patients in Group < or = 50 had a higher incidence of smoking (68% versus 51%) and a lower incidence of hypertension (29% versus 50%) than patients in group > or = 60 (smoking P = 0.03, hypertension P = 0.007). No other significant differences were noted among cardiovascular risk factors. Preoperative indications for surgery were similar among patients in both groups. An aortoiliac endarterectomy was more commonly used to revascularize the lower extremities in younger patients than in their older counterparts (23% versus 7%, P = 0.002). Graft revisions were more frequently necessary after aortic reconstruction in Group < or = 50 than in Group > or = 60 (29% versus 8%, P = 0.0003); however patency rates computed by life table analysis were not significantly different. The primary patencies for Group < or = 50 and Group > or = 60 at 5 years were 64% and 67%, respectively; their secondary patency rates at 5 years were 84% and 89%, respectively. No significant difference was found in major limb amputation (8% in Group < or = 50 versus 5% in Group > or = 60, P = 0.46). We conclude that aortoiliac reconstruction for occlusive disease can be performed with similar secondary patency and amputation rates in young and old patients. However, close postoperative surveillance and frequent surgical revision are necessary to maintain patency and minimize amputation.

Beneficial effects of donor-specific transfusions on long-term renal allograft function

The induction of immunologic unresponsiveness to improve renal allograft survival was attempted in 163 patients by the pretransplant administration of donor-specific whole blood or buffy coat in conjunction with continuous Aza immunosuppression. All donor-recipient combinations were at least one-haplotype disparate, and 21 were two-haplotype disparate. Transient sensitization occurred in 2% and permanent sensitization in 7%. Over a 10-year period, the DST+Aza allograft survival rate is similar to the HLA-identical sibling transplants. The CMV sepsis rate was only 2%, and there were no lymphoproliferative neoplasms. The low rate of sensitization (7%) has permitted almost all patients to undergo eventual renal transplantation from the specific blood donor. This and the low rate of early rejection (3%) argues for a modification of the immunologic response.

Transabdominal versus retroperitoneal incision for abdominal aortic surgery: report of a prospective randomized trial

PURPOSE

The purpose of this study was to perform a randomized, prospective trial that compares the transabdominal with the retroperitoneal approach to the aorta for routine infrarenal aortic reconstruction.

METHODS

From August 1990 through November 1993, patients undergoing surgery for abdominal aortic aneurysm (AAA) disease or aortoiliac occlusive disease (AIOD) were asked to participate in a randomized trial comparing the transabdominal incision (TAI) to the retroperitoneal incision (RPI) for aortic surgery. One hundred forty-five patients were randomized, with 75 (41 with AAA and 34 with AIOD) in the TAI group and 70 (40 with AAA and 30 with AIOD) in the RPI group. There were no significant differences between the groups in terms of age, sex, postoperative pain control (epidural vs patient-controlled analgesia), or comorbid conditions, except for a higher incidence of chronic obstructive pulmonary disease in the TAI group (21 vs 8 patients).

RESULTS

The incidence of intraoperative complications was similar for both groups. After surgery, the incidence of prolonged ileus (p = 0.013) and small bowel obstruction (p = 0.05) was higher in the TAI group. Overall, the RPI group had significantly fewer complications (p < 0.0001). The overall postoperative mortality rate (two deaths) was 1.4%, with both occurring in the TAI group (p = 0.507). The RPI group also had significantly shorter stays in the intensive care unit (p = 0.006), a trend toward shorter hospitalization (p = 0.10), lower total hospital charges (p = 0.019), and lower total hospital costs (p = 0.017). There was no difference in pulmonary complications (p = 0.71). In long-term follow-up (mean 23 months), the RPI group reported more incisional pain (p = 0.056), but no difference was found in incisional hernias or bulges (p = 0.297).

CONCLUSIONS

We conclude that the RPI approach for abdominal aortic surgery is associated with fewer postoperative complications, shorter stays in the hospital and intensive care unit, and lower cost. There is, however, an increase in long-term incisional pain. Current methods of postoperative pain control seem to decrease the incidence of pulmonary complications.

Long-term effectiveness of extraanatomic renal artery revascularization

BACKGROUND

The efficacy of direct aortorenal bypass and renal artery endarterectomy are well established. The purpose of this study is to define better the results of extraanatomic renal revascularization procedures.

METHODS

From April 1987 to March 1993, 124 patients underwent renal artery revascularization. Forty-eight (39%) of them (33 women, 15 men; average age, 65.9 years) underwent 49 extraanatomic renal artery bypasses. Preoperative risk factors included smoking in 30 patients (61%), history of myocardial infarction in 14 (29%), diabetes mellitus in 11 (22%), congestive heart failure in nine (18%), chronic obstructive pulmonary disease in 11 (22%), and stroke in six (12%). The average creatinine level was 2.3 mg/dl. The average number of antihypertensive medications was 2.4. Thirty iliorenal, 10 gastroduodenal-renal, seven hepatorenal, and two splenorenal bypasses were performed together with 10 contralateral nephrectomies.

RESULTS

Six major postoperative complications occurred. There were no deaths. Forty-one (85%) of patients had improvement or cure of their hypertension. Seven (15%) of patients failed to respond to treatment, and three required subsequent nephrectomy. After operation the average creatinine level was 1.7 mg/dl and the average number of medications was 1.7. Mean follow-up period has been 23.2 months (range, 1 to 79 months).

CONCLUSIONS

Extraanatomic bypass proved to be efficacious in treating hypertension and preserving renal function and has an acceptable rate of morbidity and mortality. We conclude that these procedures are an acceptable alternative to direct aortorenal artery revascularization.

The influence of anesthetic technique on perioperative complications after carotid endarterectomy

PURPOSE

This study evaluated the influence of anesthetic techniques on perioperative complications after carotid endarterectomy.

METHODS

Perioperative complications, the use of a carotid artery shunt, the duration of the operative procedure and postoperative hospital course were retrospectively compared in 584 consecutive patients undergoing 679 carotid endarterectomies with use of either general anesthesia (n = 361) or cervical block regional anesthesia (n = 318). There was no significant difference in the preoperative medical characteristics between the two anesthetic groups. Symptomatic carotid artery disease was the indication for surgery in 247 (68.4%) patients receiving general anesthetics, whereas 180 (56.6%) patients treated with a cervical block anesthetic had a symptomatic carotid artery stenosis (p = 0.02).

RESULTS

The perioperative stroke rate and stroke-death rate for the entire series was 2.4% and 3.2%, respectively, and was not significantly different between the anesthetic groups or between patients with symptomatic or asymptomatic disease. A carotid artery shunt was used in 61 (19.2%) patients receiving a cervical block anesthetic and 152 (42.1%) patients treated with a general anesthetic (p < 0.0001). Use of cervical block anesthesia was associated with a significantly shorter operative time, fewer perioperative cardiopulmonary complications, and a shorter postoperative hospitalization when compared with general anesthesia. Multivariate risk factor analysis indicated that age greater than 75 years, operative time greater than 3 hours, and the use of a carotid artery shunt were all independent risk factors for perioperative cardiopulmonary complications. When a carotid artery shunt was not analyzed as a multivariate risk factor, then general anesthesia became a significant risk factor for perioperative cardiopulmonary complications (risk ratio 2.08; p = 0.04).

CONCLUSIONS

We conclude that cervical block anesthesia is safer and results in a more efficient use of hospital resources than general anesthesia in the treatment of patients undergoing carotid endarterectomy.

An institutional experience with arterial atheroembolism

Seemingly minor blue-toe lesions resulting from atheroemboli are associated with unstable atherosclerotic plaques, which are at risk for causing recurrent emboli, tissue loss, and potentially death. At Washington University Medical Center, 62 patients (31 males and 31 females), ranging in age from 38 to 89 years (mean 62.8 +/- 11.7 years), were treated for cutaneous manifestations of atheroembolic disease. Most patients (62%) had spontaneous bouts of atheroembolism, but 13 (21%) had recently undergone an inciting invasive radiologic study, 10 (16%) were on anticoagulation therapy, and one (2%) experienced abdominal trauma. In addition to the cutaneous manifestations, 18 patients (29%) also developed coincidental deterioration in renal function and four (6%) had intestinal infarction from atheroemboli. Arteriography in nearly all patients (97%) implicated the aorta and iliac arteries most commonly (80%), with the femoral (13%), popliteal (3%), and subclavian (3%) arteries less frequently incriminated. Forty-two patients underwent bypass grafting procedures (36 anatomic and six extra-anatomic) after exclusion of the native diseased artery, 20 patients had endarterectomies (six with additional bypass grafts), and five patients had no corrective vascular procedures. The 30-day operative mortality rate was 5% in this series. Nineteen patients (31%) required minor amputations, whereas two required major leg amputations. Thus limb salvage was possible in 86 of 88 (98%) limbs. No further episodes of atheroembolism occurred in the involved limbs during follow-up (1 to 53 months, mean 20.2 months). We advocate urgent arteriography and surgical correction or bypass with exclusion of the offending lesion.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of the arachidonate 5-lipoxygenase synthesis inhibitor A-64077 in intestinal ischemia-reperfusion injury

This study was designed to characterize the role of arachidonate 5-lipoxygenase metabolism during experimental intestinal ischemia-reperfusion (I/R) injury. Canines were subjected to 3 hr of intestinal ischemia followed by 1 hr of normobaric reperfusion. Intestinal ischemia followed by 1 hr of normobaric reperfusion. Intestinal mucosal leukotriene B4 and leukotriene C4 synthesis tripled after ischemia and ischemia-reperfusion, relative to non-ischemic intestinal mucosa. The flux of fluid and protein from the capillary to the lumen also increased 3-fold after I/R. The selective 5-lipoxygenase synthesis inhibitor A-64077 (Ziluten, 5 mg/kg, p.o.) abolished I/R-induced leukotriene synthesis and reduced transluminal protein flux (50%) but did not influence the lumenal accumulation of fluid after I/R. In animals treated with the leukotriene synthesis inhibitor, intestinal vascular resistance significantly declined during the imposed ischemia period and after 60 min of reperfusion. Mucosal myeloperoxidase activity, a biochemical marker for tissue neutrophils, rose significantly after I/R, and these increases were prevented with the 5-lipoxygenase synthesis inhibitor. In other experiments, the lipoxygenase inhibitor nondihydroguaretic acid produced similar results to those of A64077. In an attempt to determine the source of mucosal leukotrienes during intestinal I/R, we imposed in vitro ischemia and reperfusion on normal mucosal tissue in a blood-free environment. Mucosal tissue was incubated in Krebs buffer under oxygen for 3 hr to simulate the control condition, under nitrogen for 3 hr to simulate ischemia and under nitrogen for 2 hr followed by oxygen for 1 hr to simulate I/R.(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous surgical management of aortic and renovascular disease

The results of simultaneous elective infrarenal aortic reconstruction and renovascular surgery were retrospectively reviewed in 102 patients who consecutively underwent operation. The perioperative mortality rate (0 to 54 days) was 5% (5 of 102). Renal function had returned to baseline or was improved at discharge in 89 of 97 (92%) surviving patients. The intraoperative use of renal hypothermia was an independent predictor of improved postoperative renal function, by multivariate analysis. Twenty-five of 29 (86%) patients with severe hypertension had improvement in their blood pressure on the same or fewer medications postoperatively (p = 0.0005). A retroperitoneal incision was associated with less intraoperative crystalloid fluid administration (p = 0.03), more rapid postoperative resumption of an oral diet (p = 0.04), and better long-term survival (p = 0.02) when compared with a transperitoneal incision. We conclude that the simultaneous repair of infrarenal aortic pathology and renovascular lesions is associated with an acceptable perioperative morbidity and preserves or improves renal function in the majority of patients. The frequent use of renal hypothermia and careful consideration of the route of operative exposure will lead to optimal results.

Characterization of platelet-activating factor receptors on canine T lymphocytes

The ability of purified canine T lymphocytes to selectively bind platelet activating factor (PAF) was characterized. Authentic radiolabeled PAF rapidly and selectively bound to T lymphocytes and reached saturation within 1 min. This binding was reversible and highly selective for (R) PAF because (S) PAF, lyso-PAF, and diacyl PAF did not displace the bound (R) PAF probe. Only increasing quantities of chemically pure (R) PAF displaced the radiolabeled (R) PAF probe. The binding maximum of PAF was determined to be 35 pM per 2 x 10(6) lymphocytes. Competitive radioligand binding studies and Scatchard analysis indicated a single class of high affinity receptors with a dissociation constant of 0.077 nM and a receptor density of 6419 receptors per cell. The ability of purified canine T lymphocytes to hydrolyze PAF to the biologically inactive metabolite lyso-PAF was also studied. Over a 30-min incubation period, about 5% of PAF was metabolized to lyso PAF. This rate of PAF hydrolysis was the same as the rate observed with the media without cells, suggesting a small degree of nonenzymatic hydrolysis. The effects of varying concentrations of authentic PAF on intracellular free Ca2+ release in purified T lymphocytes was evaluated using the fluorescent probe Fura-2 and excitation-emission spectrofluorometry. PAF below the concentration of 1.0 nM did not significantly increase intracellular Ca2+ in T lymphocytes. More than 1 nM PAF, intracellular-free Ca2+ modestly, but significantly, increased in T lymphocytes. In other experiments, canine PBMC proliferated in response to Con A and in the one way MLR. These proliferative responses were abolished when the selective PAF receptor antagonist SC-47014A was added to the culture medium. In the MLR, this inhibitory effect was dependent on the length of time that the antagonist was in the culture. Specifically, inhibition of proliferation was incrementally reversed when the PAF antagonist was introduced progressively later into the 7-day MLR stimulation period, suggesting that PAF receptor blockade prevents an MLR response from occurring, but is unable to suppress an existing MLR response. Although the Con A-induced mononuclear cell proliferation was abolished with PAF receptor antagonists, the addition of authentic biologically active PAF or PAF analogs did not alter the proliferative response to Con A. In conclusion, canine T lymphocytes possess high affinity receptors for PAF. These binding sites are highly selective and reversible. PAF binding slightly increases intracellular free Ca2+ in T lymphocytes and appears to be involved in lymphocyte proliferation in response to soluble plant mitogen and alloantigen.

Characterization of platelet-activating factor receptors on canine T lymphocytes

The ability of purified canine T lymphocytes to selectively bind platelet activating factor (PAF) was characterized. Authentic radiolabeled PAF rapidly and selectively bound to T lymphocytes and reached saturation within 1 min. This binding was reversible and highly selective for (R) PAF because (S) PAF, lyso-PAF, and diacyl PAF did not displace the bound (R) PAF probe. Only increasing quantities of chemically pure (R) PAF displaced the radiolabeled (R) PAF probe. The binding maximum of PAF was determined to be 35 pM per 2 x 10(6) lymphocytes. Competitive radioligand binding studies and Scatchard analysis indicated a single class of high affinity receptors with a dissociation constant of 0.077 nM and a receptor density of 6419 receptors per cell. The ability of purified canine T lymphocytes to hydrolyze PAF to the biologically inactive metabolite lyso-PAF was also studied. Over a 30-min incubation period, about 5% of PAF was metabolized to lyso PAF. This rate of PAF hydrolysis was the same as the rate observed with the media without cells, suggesting a small degree of nonenzymatic hydrolysis. The effects of varying concentrations of authentic PAF on intracellular free Ca2+ release in purified T lymphocytes was evaluated using the fluorescent probe Fura-2 and excitation-emission spectrofluorometry. PAF below the concentration of 1.0 nM did not significantly increase intracellular Ca2+ in T lymphocytes. More than 1 nM PAF, intracellular-free Ca2+ modestly, but significantly, increased in T lymphocytes. In other experiments, canine PBMC proliferated in response to Con A and in the one way MLR. These proliferative responses were abolished when the selective PAF receptor antagonist SC-47014A was added to the culture medium. In the MLR, this inhibitory effect was dependent on the length of time that the antagonist was in the culture. Specifically, inhibition of proliferation was incrementally reversed when the PAF antagonist was introduced progressively later into the 7-day MLR stimulation period, suggesting that PAF receptor blockade prevents an MLR response from occurring, but is unable to suppress an existing MLR response. Although the Con A-induced mononuclear cell proliferation was abolished with PAF receptor antagonists, the addition of authentic biologically active PAF or PAF analogs did not alter the proliferative response to Con A. In conclusion, canine T lymphocytes possess high affinity receptors for PAF. These binding sites are highly selective and reversible. PAF binding slightly increases intracellular free Ca2+ in T lymphocytes and appears to be involved in lymphocyte proliferation in response to soluble plant mitogen and alloantigen.

Preservation of renal function in juxtarenal and suprarenal abdominal aortic aneurysm repair

PURPOSE

Deterioration in renal function is a common cause of morbidity in patients treated surgically for juxtarenal and suprarenal abdominal aortic aneurysms. We reviewed our experience over the last 8 years with 65 consecutive patients undergoing juxtarenal (n = 31) or suprarenal (n = 34) abdominal aortic aneurysm repair.

METHODS

The aneurysms were repaired with a transabdominal (n = 8), thoracoabdominal (n = 4), retroperitoneal (n = 22), or thoracoretroperitoneal (n = 31) approach. Proximal aortic clamps were placed at the suprarenal, supra-superior mesenteric artery, or supraceliac level. Renal hypothermia with cold heparinized saline solution renal artery perfusion was used to protect renal function in 38 patients with either preoperative renal insufficiency or with anticipated prolonged renal ischemia (> 30 minutes). Concomitant renal artery reconstruction was required in 30 patients.

RESULTS

Significant operative morbidity developed in 23 (35.3%) patients. There was one (1.53%) perioperative death (0 to 90 days). Temporary dialysis was necessary in two patients. Preoperative renal insufficiency was a significant risk factor on multivariate analysis for a decline in renal function during the first postoperative week. However, serum creatinine concentration had returned to baseline or improved in all patients but two (3.1%) at the time of discharge. In spite of significantly longer renal ischemia, discharge creatinine levels were, on univariate analysis, statistically less than baseline creatinine levels in patients with suprarenal aneurysms, patients requiring renal reconstruction, and patients treated with renal hypothermia. The location of the proximal aortic clamp was not a factor in postoperative morbidity. There was no significant difference between juxtarenal and suprarenal aneurysms with respect to operating room time, transfusion requirements, days intubated, resumption of oral diet, or the length of hospitalization.

CONCLUSIONS

Careful consideration of the route of exposure, location of the proximal aortic clamp, and the preservation of renal function with renal hypothermia and with the repair of significant renal artery lesions will result in minimal morbidity and mortality in patients requiring surgery for juxtarenal or suprarenal abdominal aortic aneurysms.

Long-chain acyl-coenzyme A thioesters and renal hypothermic ischemic injury: effects of glycine flush

The effects of hypothermic ischemia utilizing Euro-Collins flush on renal tissue long-chain activated fatty acid content was studied in dogs. Also, the ability of the simple amino acid glycine to complex these acyl thioesters was also investigated. Renal inner cortex was found to contain (in increasing amounts) myristoyl-, palmitoleoyl-, palmitoyl-, arachidonyl-, and oleoyl-coenzyme A throughout the 3 days of cold ischemia. Although the amounts of individual long-chain acyl-CoA compounds varied considerably, the concentrations were not found to differ significantly with increasing ischemia times. The presence of 5 mM of glycine in the flush also did not influence the amount or species of long-chain acyl-CoA esters in renal tissue during cold ischemia. Ischemic renal tissue content of most long-chain acyl-CoA compounds was reduced by about 50% when the tissue underwent in vitro reperfusion with 37 degrees C O2-saturated media. Glycine included in the flush storage solution did not alter acyl-CoA levels in tissue undergoing hypothermic ischemia and short-term in vitro reperfusion with O2-saturated buffer. In conclusion, long-chain acyl-CoA thioesters are present during hypothermic renal ischemia and the levels of most of these species are reduced during in vitro reperfusion after ischemia. The quality and production mass of these metabolites appears to be unaltered by progressive hypothermic ischemia times. Finally, the protective effects of glycine in this model of renal organ preservation injury are not associated with reductions of renal tissue long-chain activated fatty acids.

Transvenous retrieval of misplaced stainless steel Greenfield filters

Transvenous retrieval was attempted in five patients following surgical misplacement of stainless steel Greenfield filters. Four filters were located within the right atrium, and one was in the left hepatic vein. All retrievals were attempted within 5 days of placement. Retrieval was successful for the four filters in the right atrium and failed for the filter in the left hepatic vein. One air embolism occurred; this was the only filter- or retrieval-related complication. Transvenous retrieval is a safe and effective minimally invasive method of removing misplaced filters.

An embolizing lesion in a minimally diseased aorta

A case report of a patient with an unusual source of emboli resulting in acute limb-threatening ischemia is presented. Diagnostic angiography of the lower extremity was performed, followed by thromboembolectomy, which successfully restored normal arterial flow to the threatened leg. After surgery the patient underwent transesophageal echocardiography, which failed to identify an embolic source. Because of the high degree of clinical suspicion that the primary disease process was embolic rather than thrombotic, a thorough evaluation of the arterial tree was performed, including computed tomography and aortography. A large, mobile intravascular lesion arising from a normal descending thoracic aorta was identified and successfully treated with resection and graft placement.

Selective loss of functional antidonor cytolytic T cell precursors following donor-specific blood transfusions in long-term renal allograft recipients

Pretransplant administration of donor-specific blood transfusions prolongs the survival of HLA-disparate renal allografts to a level comparable to that of HLA-identical transplants. To test the hypothesis that DST recipients develop immunologic tolerance of their donors, we examined antidonor T cell immunity in a group of DST recipients with long-term well-functioning allografts. Limiting dilution analysis studies indicated that 5/14 long-term DST recipients exhibit a complete absence of detectable antidonor cytolytic T lymphocyte precursors (CTLp). In contrast, 4/4 long-term non-DST recipients who received conventional or cyclosporine immunosuppression exhibited significant levels of antidonor CTLp. Nonresponsive DST recipients retained the capacity to mount antidonor responses in mixed lymphocyte reactions and IL-2 production assays, and exhibited normal levels of CTLp directed to third-party antigens. Addition of exogenous IL-2 to cell-mediated lympholysis cultures did not restore antidonor CTL responses. In summary, our data suggest that the DST conditioning regimen induces a complete yet selective loss of functional antidonor CTLp in some long-term renal transplant recipients.

In situ saphenous vein for lower extremity revascularization

BACKGROUND

During a 6-year period, 349 in situ saphenous vein bypass grafts were performed for limb salvage by three surgeons.

METHODS

Outflow anastomoses were constructed to the infrageniculate popliteal (25%), posterior tibial (20%), peroneal (20%), anterior tibial (19%), and dorsal pedal arteries (7%). Mean patient age was 70 1/2 years.

RESULTS

The 30-day mortality rate was 3.2%, and 19% died during the ensuing 68-month interval. At 1, 24, and 60 months primary graft patency was 89%, 77%, and 74%, secondary graft patency was 91%, 80%, and 78%, and cumulative limb survival was 94%, 88%, and 84%, respectively. Cumulative patency rates at 60 months depending on outflow site were as follows: popliteal (85%), anterior tibial (80%), posterior tibial (70%), dorsal pedal (68%), and peroneal (60%). Patency at the peroneal position was significantly inferior to that of other infrapopliteal sites combined (p less than 0.05). Cumulative limb survival at 60 months, according to outflow site, was as follows: popliteal (95%), anterior tibial (85%), posterior tibial (78%), dorsal pedal (73%), and peroneal (67%). There was no significant difference in limb salvage among infrapopliteal outflow sites. However, patency rates and limb salvage were significantly better for the popliteal outflow site than the infrapopliteal outflow sites (p less than 0.01).

CONCLUSIONS

(1) A 5-year graft patency rate of 78% and a limb salvage rate of 84% are achievable, (2) peroneal bypass is associated with a lower rate for graft patency but not limb salvage, and (3) popliteal bypass has the best graft patency and limb salvage rates.

Selective non-operative management of pseudoaneurysms and arteriovenous fistulae complicating femoral artery catheterization

Femoral arterial pseudoaneurysms or arteriovenous fistulae may sometimes complicate percutaneous femoral artery catheterization procedures. Most surgeons recommend prompt operative repair because of the unfavorable natural history of pseudoaneurysms or arteriovenous fistulae secondary to violent or accidental arterial trauma. However, the natural history of catheterization-induced pseudoaneurysms and arteriovenous fistulae has not been well documented. Accordingly, we prospectively studied the natural history of 22 pseudoaneurysms, 8 arteriovenous fistulae, and 3 combined lesions, identified by duplex scan in 32 patients following trans-femoral cardiac, peripheral vascular, or vascular access arterial catheterization procedures. Angiographic procedures were performed with the use of 5-8F introducer sheaths. A femoral artery complication was significantly more likely to result from coronary balloon angioplasty (9/304; 3.0%) than from diagnostic cardiac catheterization (21/2476; 0.8%) (p less than 0.003; chi square). Fourteen patients (13 pseudoaneurysms, 1 combined pseudoaneurysm/fistulae) underwent surgical repair. Pain and/or enlarging hematoma resulted in repair within two days of the diagnosis in 8 patients. The need for chronic anticoagulation prompted elective repair in 2 patients. A pseudoaneurysm was repaired in one patient five days following catheterization when it became painful. In three stable patients, asymptomatic pseudoaneurysms were repaired electively during another surgical procedure. There were no operative deaths. One patients (7%) developed a wound infection postoperatively. Eighteen patients (19 arterial lesions: 9 pseudoaneurysms, 8 arteriovenous fistulae, 2 combined pseudoaneurysms/arteriovenous fistulae) with improving symptoms and stable physical signs were followed by serial clinical evaluation and duplex scans. Seventeen of 19 (89%) of these lesions resolved spontaneously within 5-90 days (mean 30.7 days).(ABSTRACT TRUNCATED AT 250 WORDS)

Improved and simplified tissue extraction method for quantitating long-chain acyl-coenzyme A thioesters with picomolar detection using high-performance liquid chromatography

A method has been developed that permits rapid and easy tissue extraction of long-chain acyl-coenzyme A (acyl-CoA) thioesters with sensitive quantitation by reversed-phase high-performance liquid chromatography (RP-HPLC). Tissue homogenants are extracted using a reserve Bligh-Dyer technique, and long-chain acyl-CoA esters are harvested in the methanolic aqueous phase. Complex lipids and phospholipids are removed in the chloroform-rich organic Bligh-Dyer second phase, and long-chain acyl-CoA compounds are further purified from the methanolic aqueous Bligh-Dyer first phase on C18 extraction columns after removal of the methanol. The eluted and purified acyl-CoA esters are then quantitated by RP-HPLC using heptadecanoyl-CoA as an internal standard resulting in a detector sensitivity of about 12 pmol. Ten long-chain acyl-CoA esters from C12:0 to C20:4 were identified and separated from canine renal cortex and murine liver samples. The predominant acyl-CoA peaks from both kidney and liver were 14:0, 16:1, 16:0, 18:1, 18:2 and 20:4. Murine liver also produced 18:0 and all peaks disappeared after alkaline hydrolysis of the samples. This extraction and quantitation technique can successfully be used for tissue samples as small as 20 mg, and many samples can be processed in a short period of time. The simplicity of the extraction procedure and the sensitivity of the assay make this an attractive alternative approach to quantitating long-chain acyl-CoA thioesters from complex biological samples such as tissues.

Detection of the source of arterial emboli by transesophageal echocardiography: a case report

We report a case acute lower extremity ischemia caused by emboli in which the initial diagnostic evaluation, including standard aortoiliofemoral arteriography and routine transthoracic two-dimensional echocardiography, failed to reveal the offending source. Because of the strong clinical suspicion that the origin of the arterial occlusion was embolic, transesophageal echocardiography was performed. Transesophageal echocardiography demonstrated an aortic valvular lesion and cardiac surgery was performed on an emergency basis. The use of transesophageal echocardiography in evaluating the heart and thoracic aorta as a source of distal emboli is also discussed.

Protective effects of glycine during hypothermic renal ischemia-reperfusion injury

The objective of this investigation was to test the effects of glycine, a cytoprotectant in normothermic in vitro models of renal ischemia, in a model of hypothermic renal preservation injury. This study also probes possible physiological mechanisms of glycine protection during renal hypothermic ischemia-reperfusion injury. Canine kidneys were subjected to 48 h of hypothermic ischemia (4 degrees C) after intravascular flush with cold conventional Collins solution (G. H. Collins, M. B. Bravo-Shugarman, and P. I. Terasaki, Lancet 2: 1219-1223, 1969) and were subsequently revascularized for 1 h. After 1 h of reperfusion, glomerular filtration rate, urine production, and electrolyte excretion were dramatically higher when the Collins flush contained 5 mM glycine, compared with the 0 mM glycine controls. Renal tissue adenine nucleotides and glutathione levels progressively declined with graded cold ischemia times, and glycine had no effect on these levels. However, renal tissue ATP levels (but not glutathione) were significantly higher when kidneys were flushed with glycine, stored for 48 h, and reoxygenated in vitro for 1 h at 37 degrees C, compared with kidneys flushed without glycine. Analysis of CoA esters from ischemic renal tissue indicated altered production of only butyryl CoA after 48 and 72 h of cold ischemia, but no differences were detected in glycine or control kidneys. In conclusion, this study reports dramatic functional preservation with glycine in kidneys subjected to hypothermic ischemia and in vivo reperfusion. The mechanisms of these effects appear not to be attributable to the maintenance of cellular adenine nucleotide or glutathione levels nor to the scavenging of accumulated amphipathic acyl CoA esters.

Renal allograft platelet activating factor synthesis during acute cellular rejection

The aim of this study was to characterize the synthesis and metabolism of platelet activating factor (PAF, 1-0-alkyl-2-0 acetyl-sn3-phosphorylcholine) by renal tissue undergoing acute cellular allograft rejection in the canine model. Kidneys were transplanted into outbred mongrel dogs and allowed to reject without immunosuppressive therapy. Five days after transplantation, all kidneys were non-functional and the tissue was assayed for the capacity to produce various molecular species of PAF and lyso-PAF using physical-chemical (GC/MS), immunologic (RIA) and biologic (platelet aggregation) assays. Renal cortical tissue obtained from rejecting allografts produced more PAF than control tissue by the following factors (GC/MS): 18-fold for C16:0 PAF; 3-fold for Lyso-C16:0 PAF; 2-fold for C18:1 PAF; and 6-fold for C18:0 PAF. The control tissue to which comparisons were made was renal cortex obtained from the native contralateral kidney. Increases in the production of various molecular species of PAF were also observed with renal medullary tissue undergoing acute rejection, although the magnitude of change was less dramatic than with renal cortex. The predominant PAF metabolite produced both by normal and allograft tissue was C16:0 Lyso-PAF. The increased PAF production by renal allograft tissue undergoing rejection was mainly attributable to C16:0 PAF and C16:0 Lyso-PAF, but increased production of both C18:0-PAF and of C18: 1-PAF was also detected. Increased renal allograft PAF production was also confirmed with a competitive binding immunoassay specific for PAF. In addition, when PAF-like material was isolated and purified from renal allograft incubation media and added to washed canine platelets, an intense aggregation response was observed that was abolished with prior alkaline methanolysis of the isolated material. Aggregation responses of similar magnitude were not obtained with PAF-like material isolated from native (non-rejection) renal tissue. In other experiment, incubation media obtained from rejecting renal allografts was found to contain factor which catalyzed hydrolysis of exogenous PAF to Lyso- PAF at twice the rate induced by media obtained from normal renal tissue. In conclusion, this study has identified dramatic increases in production of the biologically active molecular species of PAF by renal allograft tissue undergoing untreated cellular rejection. High levels of biologically inactive Lyso-PAF were also detected, and renal allograft tissue elaborates a factor which catalyzes rapid hydrolysis of PAF.

Prostanoids and hypothermic renal preservation injury

The effect of 48 hours of hypothermic renal ischemia utilizing Euro-Collins flush and short term reperfusion on renal prostaglandin synthesis was studied in dogs. Hypothermic ischemia followed by 60 minutes of reperfusion in-vivo resulted in significant elevations in renal Thromboxane B2 (TXB2) production in the outer cortex, inner cortex, and medulla, relative to non-ischemic kidneys. Prostaglandin E2 (PGE2) and 6-keto Prostaglandin F1 alpha (6-K PGF1 alpha) production were not significantly affected by ischemia and reperfusion. Enhanced TXB2 production was not seen with ischemia alone (without reperfusion) or with reperfusion with O2 saturated buffer, indicating a blood born source or stimuli. Early postreperfusion renal blood flow after hypothermic ischemia followed a biphasic pattern; blood flow increased for the first 10 minutes of reperfusion to achieve normal values, and then steadily declined over the next 20 minutes. This pattern was not altered by the cyclooxygenase inhibitors Idomethacin (5 mg/kg, P.O.) or Mefenamic acid (10 mg/kg, I.V.). Administration of the TXA2 synthesis inhibitor CGS-12970 (3 mg/kg, I.V.) or the TXA2/endoperoxide receptor antagonist SQ-29548 (80 micrograms/min, I.A.) significantly increased renal blood flow during reperfusion but neither agent altered the basic time dependent pattern observed in the control group. These data indicate that 48 hours of hypothermic renal ischemia results in dramatic changes in intrarenal TXA2 synthesis at the time of reperfusion. Enhanced TXA2 production is not dependent on reoxygenation per se, but rather requires reperfusion with blood suggesting a circulatory source.(ABSTRACT TRUNCATED AT 250 WORDS)

Vascular access in patients with arterial insufficiency. Construction of proximal bridge fistulae based on inflow from axillary branch arteries

Patients with renal failure and underlying peripheral vascular disease pose a difficult management problem in establishing long-term angioaccess for chronic hemodialysis. This report summarizes our experience with five debilitated patients who developed acute upper extremity ischemia after forearm fistula construction corrected by fistula ligation. Successful angioaccess was achieved without ischemia recurrence by construction of proximal bridge fistulae with arterial inflow based on branch arteries of the axillary artery. The relatively small size of the branch vessel was the main factor in limiting fistula flow while permitting normal distal axillary artery flow. In four patients direct fistula flow measurements ranged from 200 mL per minute to 620 mL per minute. Axillary arterial flow distal to the fistula ranged from 120 to 200 mL per minute and did not significantly change after fistula construction or during temporary occlusion of the fistula. Four of the five patients continue to dialyze uneventfully from 4 to 8.5 months. One patient died after discontinuation of dialysis 1 month after operation.

Intestinal parasites of conventionally maintained BALB/c mice and Mastomys coucha and the effects of a concomitant schistosome infection

A longitudinal study was carried out to identify the spectrum of intestinal parasites present in conventionally maintained BALB/c mice and Mastomys coucha and to determine the effects of concomitant schistosome infections on their parasite status. Six parasites were observed during the course of the study, namely the nematodes Aspiculuris tetraptera and Syphacia obvelata, Entamoeba muris and the flagellates Trichomonas muris, Spironucleus muris and Chilomastix spp. Although the 2 rodents shared common facilities, the overall prevalences of S. obvelata, T. muris and S. muris were significantly higher in M. coucha than BALB/c mice. BALB/c mice with concomitant schistosome infection had increased prevalences of E. muris, T. muris and S. muris. In M. coucha, in contrast, there were no significant increases in parasite prevalences. Infection intensities of T. muris and S. muris were significantly greater in M. coucha than BALB/c mice. Concomitant schistosome infection resulted in increased intensities of T. muris infection in BALB/c mice only. The influence of immune status in determining the susceptibilities of rodents to environmentally transmitted parasites is discussed.