Dual signaling regulated by calcyon, a D1 dopamine receptor interacting protein.

The synergistic response of cells to the stimulation of multiple receptors has been ascribed to receptor cross talk; however, the specific molecules that mediate the resultant signal amplification have not been defined. Here a 24-kilodalton single transmembrane protein, designated calcyon, we functionally characterize that interacts with the D1 dopamine receptor. Calcyon localizes to dendritic spines of D1 receptor-expressing pyramidal cells in prefrontal cortex. These studies delineate a mechanism of Gq- and Gs-coupled heterotrimeric GTP-binding protein-coupled receptor cross talk by which D1 receptors can shift effector coupling to stimulate robust intracellular calcium (Ca2+i) release as a result of interaction with calcyon. The role of calcyon in potentiating Ca2+-dependent signaling should provide insight into the D1 receptor-modulated cognitive functions of prefrontal cortex.

Purification and sequence analysis of bioactive atrial peptides (atriopeptins).

Mammalian cardiac atria have several biologically active peptides that exert profound effects on sodium excretion, urine volume, and smooth muscle tone. In the present study two such peptides of low molecular weight were purified and separated from each other on the basis of differences in charge, hydrophobicity, and biological profile. The first peptide, designated atriopeptin I, exhibits natriuretic and diuretic activity and selectivity relaxes intestinal smooth muscle but not vascular smooth muscle strips. The second peptide, atriopeptin II, is a potent natriuretic and diuretic that relaxes both intestinal and vascular strips. Sequence analysis of atriopeptin I indicates that it is composed of 21 amino acids, of which serine and glycine residues predominate. The amino terminal sequence of atriopeptin II up to residue 21 is the same as that of atriopeptin I, with the addition of the Phe-Arg extension at the carboxyl terminus. Both peptides appear to be derived from a common high molecular weight precursor (designated atriopeptigen); their biological selectivity and potency may be determined by the site of carboxyl terminal cleavage.

Hypersensitive substrate for ribonucleases.

A substrate for a hypersensitive assay of ribonucleolytic activity was developed in a systematic manner. This substrate is based on the fluorescence quenching of fluorescein held in proximity to rhodamine by a single ribonucleotide embedded within a series of deoxynucleotides. When the substrate is cleaved, the fluorescence of fluorescein is manifested. The optimal substrate is a tetranucleotide with a 5',6-carboxyfluorescein label (6-FAM) and a 3',6-carboxy-tetramethylrhodamine (6-TAMRA) label: 6-FAM-dArUdAdA-6-TAMRA. The fluorescence of this substrate increases 180-fold upon cleavage. Bovine pancreatic ribonuclease A (RNase A) cleaves this substrate with a k (cat)/ K (m)of 3.6 x 10(7)M(-1)s(-1). Human angiogenin, which is a homolog of RNase A that promotes neovascularization, cleaves this substrate with a k (cat)/ K (m)of 3. 3 x 10(2)M(-1)s(-1). This value is >10-fold larger than that for other known substrates of angio-genin. With these attributes, 6-FAM-dArUdAdA-6-TAMRA is the most sensitive known substrate for detecting ribo-nucleolytic activity. This high sensitivity enables a simple protocol for the rapid determination of the inhibition constant ( K (i)) for competitive inhibitors such as uridine 3'-phosphate and adenosine 5'-diphos-phate.

Percutaneous cervical oesophageal cannulation in the dog for the performance of prolonged oesophageal pH and manometric studies.

Traditional methods for obtaining oesophageal access in experimental animals are unsuitable for prolonged (24 h) oesophageal pH evaluation, a procedure that is commonly employed in the assessment of human patients suspected of having gastroesophageal reflux disease. In the present study, we describe a six-year experience with a technique of percutaneous oesophagostomy for the performance of serial 24 h oesophageal pH and manometric studies involving 62 dogs and a total of 208 oesophageal cannula placement procedures. The results indicate a considerable improvement over previously described techniques with respect to simplicity of surgical technique, associated morbidity, oesophagostomy management, animal conditioning, and avoidance of chemical and excessive physical restraints in animals undergoing oesophageal pH and manometric evaluation.

A new class of bradykinin antagonists: synthesis and in vitro activity of bissuccinimidoalkane peptide dimers.

A systematic study on the dimerization of the bradykinin (BK) antagonist D-Arg0-Arg1-Pro2-Hyp3-Gly4-Phe5-Ser6-D-Phe 7-Leu8-Arg9 has been performed. The first part of this study involved compounds wherein dimerization was carried out by sequentially replacing each amino acid with cysteine and cross-linking with bismaleimidohexane. The second part of this study utilized a series of bissuccinimidoalkane dimers wherein the intervening methylene chain was varied systematically from n = 2 to n = 12 while the point of dimerization was held constant at position 6. The biological activities of these dimers were then evaluated on BK-induced smooth muscle contraction in two different isolated tissue preparations: guinea pig ileum (GPI) and rat uterus (RU). Several of the dimeric BK antagonists displayed remarkable activities and long durations of action. In addition, dimerization at position 4, 7, 8, or 9 produced dimeric analogues with markedly reduced potency. Rank order of antagonist potency as a function of dimerization position is as follows: rat uterus, 6 greater than 5 greater than 0 greater than 2 greater than 1 greater than 3 much greater than 4, 7, 8, 9; guinea pig ileum, 6 greater than 5 greater than 3 greater than 2 greater than 1 greater than 0 much greater than 4, 7, 8, 9. Evaluation of the linker length as represented by the number of methylene units indicated an optimal distance between the two monomeric peptides of six to eight methylene moieties. These studies also revealed that the carbon-chain length significantly affected the duration of action in vitro and resulted in partial agonism effects when n greater than 8. The optimum activity in vitro was achieved with dimerization at position 6 and n = 6 (designated herein as compound 25; alternatively, CP-0127). Similar effects in potency were also seen when the monomeric antagonist D-Arg0-Arg1-Pro2-Hyp3-Gly4-Phe5-Ser6-D-Phe 7-Phe8-Arg9 (NPC-567) was dimerized using similar chemistry. These results suggest that the development of BK antagonists of significant therapeutic potential may be possible using a dimerization strategy that can overcome the heretofore limiting problems of potency and in vivo duration of action found with many of the BK antagonists in the literature.

Improved technique of laparoscopic nephrectomy for multicystic dysplastic kidney.

We report removal of a multicystic dysplastic kidney with a laparoscopic technique that uses only three trocar sites. Additionally, we have found placement of a ureteral catheter and full mechanical and antibacterial bowel cleansing unnecessary. The role of this surgery in the management of multicystic dysplastic kidney is discussed.

Low insertion of hepatic segmental duct VII-VIII is an important cause of major biliary injury or misdiagnosis.

BACKGROUND: The importance of variant anatomy is only mentioned generally in most articles in this era of laparoscopic cholecystectomy. We report a series of 14 patients in whom a seemingly low insertion of hepatic segmental duct VII-VIII was clinically important. METHODS: The patients were managed at Duke University Medical Center. Two intraoperative videotapes of injury were reviewed. RESULTS: Three categories of patients were identified: 6 patients who had injury in association with another major injury to the biliary system, 7 patients who had an isolated VII-VIII system injury, and 1 patient with a Klatskin tumor in whom the unobstructed variant duct was stented. After appropriate evaluation, all patients were successfully treated. Several lawsuits resulted, even when the injury was seemingly minor. Symptoms developed in all patients who filed lawsuits, but none in those who did not. CONCLUSION: Appreciation of the VII-VIII biliary variant can lead to avoidance of injury or to a successful repair. The injury can easily occur despite "normal" cholangiography. Successful clinical outcome does not necessarily correlate with freedom from lawsuits.

Laparoscopic colectomy. Prospects and problems.

This article provides a fundamental review of laparoscopic colectomies. An overview of the physiology of laparascopic procedures is given as an introduction to the rationale of laparoscopic colectomies. A review of the current published literature including indications and an overview of laparoscopic bowel procedures for malignant diseases are presented.

Naturally occurring muscle pain during exercise: assessment and experimental evidence.

The objectives were: (i) to present a method for assessing muscle pain during exercise, (ii) to provide reliability and validity data in support of the measurement tool, (iii) to test whether leg muscle pain threshold during exercise was related to a commonly used measure of pain threshold pain during test, (iv) to examine the relationship between pain and exertion ratings, (v) to test whether leg muscle pain is related to performance, and (vi) to test whether a large dose of aspirin would delay leg muscle pain threshold and/or reduce pain ratings during exercise. In study 1, seven females and seven males completed three 1-min cycling bouts at three different randomly ordered power outputs. Pain was assessed using a 10-point pain scale. High intraclass correlations (R from 0.88 to 0.98) indicated that pain intensity could be rated reliably using the scale. In study 2, 11 college-aged males (age 21.3 +/- 1.3 yr) performed a ramped (24 W.min-1) maximal cycle ergometry test. A button was depressed when leg muscle pain threshold was reached. Pain threshold occurred near 50% of maximal capacity: 50.3 (+/- 12.9% Wmax), 48.6 (+/- 14.8% VO2max), and 55.8 (+/- 12.9% RPEmax). Pain intensity ratings obtained following pain threshold were positively accelerating function of the relative exercise intensity. Volitional exhaustion was associated with pain ratings of 8.2 (+/- 2.5), a value most closely associated with the verbal anchor "very strong pain." In study 3, participants completed the same maximal exercise test as in study 2 as well as leg cycling at 60 rpm for 8 s at four randomly ordered power outputs (100, 150, 200, and 250 W) on a separate day. Pain and RPE ratings were significantly lower during the 8-s bouts compared to those obtained at the same power outputs during the maximal cycle test. The results suggest that noxious metabolites of muscle contraction play a role in leg muscle pain during exercise. In study 4, moderately active male subjects (N = 19) completed two ramped maximal cycle ergometry tests. Subjects drank a water and Kool-Aid mixture, that either was or was not (placebo) combined with a 20 mg.kg-1 dose of powdered aspirin 60 min before exercise. Paired t-tests revealed no differences between conditions for the measures of exercise intensity at pain threshold [aspirin vs placebo mean (+/- SD)]: power output: 150 (+/- 60.3 W) versus 153.5 (+/- 64.8 W); VO2: 21.3 (+/- 8.6 mL.kg-1.min-1) versus 22.1 (+/- 10.0 mL.kg-1.min-1); and RPE: 10.9 (+/- 3.1) versus 11.4 (+/- 2.9). Repeated measures ANOVA revealed no significant condition main effect or condition by trial interaction for pain responses during recovery or during exercise at 60, 70, 80, 90, and 100% of each condition's peak power output. It is concluded that the perception of leg muscle pain intensity during cycle ergometry: (i) is reliably and validly measured using the developed 10-point pain scale, (ii) covaries as a function of objective exercise stimuli such as power output, (iii) is distinct from RPE, (iv) is unrelated to performance of the type employed here, and (v) is not altered by the ingestion of 20 mg.kg-1 acetylsalicylic acid 1 h prior to the exercise bout.

Histologic evaluation of fetal brains following maternal pneumoperitoneum.

BACKGROUND: The purpose of this study was to determine if maternal pneumoperitoneum with carbon dioxide (CO2) produces evidence of central nervous system (CNS) injury in preterm fetal guinea pigs. METHODS: Thirty pregnant guinea pigs at gestational day (GD) 45 were assigned at random to one of three treatment groups: anesthesia only, CO2 pneumoperitoneum (5 mmHg), or laparotomy. Dams were killed 3 or 5 days postprocedure and fetal brains (83 total) harvested and fixed for subsequent histopathologic evaluation. For comparative purposes, histologic features of fetal guinea pig brain injury were defined from examination of fetal brains harvested from an additional dam that underwent laparotomy with 20 min of uterine arterial occlusion. RESULTS: Carbon dioxide pneumoperitoneum did not increase maternal/fetal morbidity. No evidence of brain injury was found in fetuses from any of the treatment groups. CONCLUSION: Carbon dioxide pneumoperitoneum at 5 mmHg for 40 min in the pregnant guinea pig does not produce evidence of fetal brain injury.

Laparoscopic antireflux surgery in the lung transplant population.

BACKGROUND: Lung transplantation has emerged as a viable therapeutic option for patients with a variety of end-stage pulmonary diseases. As immediate posttransplant surgical outcomes have improved, the greatest limitation of lung transplantation remains chronic allograft dysfunction. Gastroesophageal reflux disease (GERD) with resultant aspiration has been implicated as a potential contributing factor in allograft dysfunction. GERD is prevalent in end-stage lung disease patients, and it is even more common in patients after transplantation. We report here on the safety of laparoscopic fundoplication surgery for the treatment of GERD in lung transplant patients. METHODS: Eighteen of the 298 lung transplants performed at Duke University Medical Center underwent antireflux surgery for documented severe GERD. The safety and benefit of laparoscopic fundoplications in this population was evaluated. RESULTS: The antireflux surgeries included 13 laparoscopic Nissen fundoplications, four laparoscopic Toupets, and one open Nissen (converted secondary to extensive adhesions). Two of the 18 patients reported recurrence of symptoms (11%), and two others reported minor GI complaints postoperatively (nausea, bloating). There were no deaths from the antireflux surgery. After fundoplication surgery, 12 of the 18 patients showed measured improvement in pulmonary function (67%). CONCLUSIONS: GERD occurs commonly in the posttransplant lung population. Laparoscopic fundoplication surgery, when indicated, can be done safely with minimal morbidity and mortality. In addition to the resolution of reflux symptoms, improvement in pulmonary function may be seen in this population after fundoplication. Lung transplant patients with severe GERD should be strongly considered for antireflux surgery.

Laparoscopy and the internet. A surgeon survey.

BACKGROUND: The Internet has become an important new tool for the delivery and acquisition of medical information. METHODS: A 13-item questionnaire designed to collect information on the attitudes and practices of surgeons regarding the use of the Internet as a medical resource was posted on the World Wide Web and also sent via e-mail. RESULTS: Over a 2-month period, 459 surgeons were enrolled in this study. Most of the respondents were identified as male surgeons (96%) between the ages of 31 and 50 years (79.25%). They accessed the Internet mainly from their homes (67.10%) and offices (17%) using 56 Kbps (34.86%) and 33.6 Kbps (21.79%) modems. These participants indicated that they use the Internet to expand their knowledge of general surgery (78.87%), learn more about technologies related to the practice of surgery (74.51%), access the Medline medical database (73.20%), and locate other resources for academic purposes (68%). Approximately half of them said that they favored the use of robotic assist devices in the operating room (53%), and most supported the use of technology for telementoring purposes (78%). Almost 80% professed an interest in video streaming technology applied to surgical education. CONCLUSIONS: This study showed that the Internet is a useful and powerful real-time survey tool that can help us to assess the impact of the World Wide Web and related technologies on surgical education and practice. However, the respondents in this study belong to a biased group that is already familiar with the Internet and computer technology and thus may not be representative of the surgical community as a whole.

An institutional review of the management of choledocholithiasis in 1616 patients undergoing laparoscopic cholecystectomy.

At Georgia Baptist Medical Center, 1616 patients underwent laparoscopic cholecystectomy between December 1989 and December 1992; and 103 perioperative endoscopic retrograde cholangiopancreatography (ERCP) procedures were performed, 79 preoperative and 24 postoperative. Endoscopic sphincterotomy with stone extraction was performed in 49 patients (4.7%). Normal ERCP was noted in 46 patients (44%), four patients failed stone extraction preoperatively, and two patients failed extraction postoperatively (5.7%). Four patients had small stones (< 2 mm) managed expectantly without sphincterotomy. Ten laparoscopic common bile duct explorations and eight open common bile duct explorations were performed without retained stones after these procedures. The incidence of detected choledocholithiasis requiring intervention was 4.4 per cent, which is significantly lower than the published incidence of 8 to 15 per cent. It is assumed that a higher percentage of stones may have been detected with liberal or routine use of cholangiography. The clinical significance of these potentially missed stones have not been manifest in our series to date. The authors believe that although improved patient selection may lower the percentage of normal ERCP, this combination of minimally invasive techniques provides a satisfactory approach to choledocholithiasis.

1525 laparoscopic cholecystectomies without biliary injury: a single institution's experience.

Laparoscopic Cholecystectomy (LC) has become the preferred treatment of gallbladder disease. The indications for LC remain unchanged from those for open cholecystectomy (OC). A total of 1525 patients underwent LC at Georgia Baptist Medical Center between December 1989 and December 1992. The procedure was completed in 1,492 patients (97.8%) and required conversion to OC in 33 patients (2.2%). Selective intraoperative cholangiography was used in 165 patients (10.8%). Overall morbidity was 4.06%, and there were four deaths not operatively related, for a 0.26% mortality rate. There have been no biliary ductal injuries. The average hospital stay was 0.82 days, with 37.4% of the patients going home as true outpatients and 44.5% going home on postop Day one. Most published series on LC report a small incidence of biliary injury. We feel that with meticulous dissection of the cystic duct and use of selective intraoperative cholangiography to define unsure anatomy, biliary injury can be minimized.

Design and application of a rapid screening technique for isolation of selenite reduction-deficient mutants of Shewanella putrefaciens.

A rapid screening technique for isolation of selenite (Se(IV)) reduction-deficient (Ser) mutants was developed and used to identify four Ser mutants of Shewanella putrefaciens. Two Ser mutants were unable to grow anaerobically on fumarate, nitrate or nitrite. Two other Ser mutants were unable to grow anaerobically on all compounds tested as sole terminal electron acceptor. Previously isolated Mn(IV) reduction-deficient mutants displayed Ser-positive phenotypes and reduced Se(IV) at wild-type rates, while two of nine Fe(III) reduction-deficient mutants displayed Ser-negative phenotypes and reduced Se(IV) at low rates. This study provides the first reported method for isolation of Ser mutants and demonstrates that Se(IV) reduction by S. putrefaciens is respiratory chain-linked.

Videoendoscopic endotracheal intubation of the rat.

Mechanical ventilation is essential to the proper maintenance of anaesthesia in research animals undergoing laparoscopic research investigations with prolonged pneumoperitoneum. Ventilatory assistance is greatly aided by endotracheal intubation, which in rats can be a challenging procedure with a substantial risk of complication. The difficulty of the procedure arises primarily from the limited exposure and access to the laryngeal opening. We describe a simple and safe technique for endotracheal intubation in the rat that permits the introduction of a large-bore tube under direct visualization using equipment commonly found in the endosurgical research setting.

Endoscopic surgery of the upper extremity.

Endoscopic techniques for surgery of the upper extremity show great promise based on recent discoveries of anatomic tissue planes. These planes can be dissected using new technology consisting of endoscopic balloons that create optical cavities that permit "incisionless" surgery. This article contains a review of the anatomic principles, new surgical technology, and development of endoscopic tools, as well as an example of endoscopic tissue expansion placement for soft-tissue augmentation in the upper extremity. Endoscopic techniques as they relate to fractures, synovectomy, and peripheral nerve decompression are discussed.

Atriopeptins: bioactive peptides derived from mammalian cardiac atria.

Mammalian atria possess bioactive peptides that are natriuretic-diuretic and potent relaxants of vascular and nonvascular smooth muscle. Characterization of the biological activity of rat atrial extracts indicates two major peaks, having apparent molecular weight of 20,000-30,000 (atriopeptigen) and less than 10,000 (atriopeptins). The amino acid sequence of atriopeptins I, II and III have been determined, and it has been found that their structures are only slightly different. Atriopeptin I (twenty-one amino acid residues); ser-ser-cys-phe-gly-gly-arg-ile-asp-arg-ile-gly-ala-gln-ser-gly-leu-gly- cys- asn-ser) relaxes intestinal but not vascular smooth muscle strips, and is natriuretic. Atriopeptins II and III (23 and 24 residues; the 21-sequence of I with the addition of phe-arg or phe-arg-tyr at the C-terminus, respectively) relax intestinal and vascular smooth muscle strips and are potent natriuretics. Since atriopeptigen and the atriopeptins exhibit similar biological effects the possibility of a precursor-product relationship was tested. Mild proteolytic digestion (1IU/ml trypsin) of atriopeptigen activates this peptide and reduces its apparent molecular weight. Examination of whether the atria of Krebs perfused isolated hearts released the bioactive atrial peptides revealed the presence in the cardiac effluent of a trypsin-labile substance that was natriuretic-diuretic and a smooth muscle relaxant. To determine which form of the atrial peptide (e.g. atriopeptigen or atriopeptin) is released by the atria the cardiac effluents were concentrated and partially purified. The cardiac effluent contained a substance(s) similar to atriopeptin, but did not appear to possess the less-active high molecular weight peptide, atriopeptigen.(ABSTRACT TRUNCATED AT 250 WORDS)