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Biomedical subjects

J A Ryan

Publications and source records attributed to J A Ryan.

At least 19 recordsLinked to original sources
PubMed1997

Effectiveness and safety of 100 consecutive parathyroidectomies.

BACKGROUND AND METHODS: In order to evaluate the indications for operation for patients with primary hyperparathyroidism, prospective information was gathered on 100 consecutively operated patients from 1991 to 1996. A standard evaluation for outcomes and patient satisfaction was instituted. Patients consisted of 73 women and 27 men. Major symptoms existed in 48 patients, and 52 patients were referred to as "asymptomatic" because they fit the National Institutes of Health Consensus Development Conference Statement with abnormal laboratory values. The pathology was 94 single adenomas, 4 double adenomas, and 2 cases of hyperplastic multiglandular disease. RESULTS: All 100 patients had abnormal parathyroids removed, resulting in normocalcemia in 97. Three patients had persistent hypercalcemia until a second operation removed additional abnormal parathyroids, resulting in normocalcemia. No operative complications or mortality occurred. Overnight stay occurred in 88 patients. During long-term follow-up of patients, only 2 developed recurrent hyperparathyroidism. When asked whether the operation improved their health, 94% of patients with major symptoms and 72% of asymptomatic patients responded affirmatively. CONCLUSION: Parathyroidectomy is an efficient and safe operation with excellent normalization of serum calcium and a high rate of patient satisfaction.

Adolescent↗
PubMed1997

Cavernous hemangiomas of the liver: enlargement over time.

OBJECTIVE: It has been reported that cavernous hemangiomas of the liver either do not enlarge over time, or, of the very few lesions that have shown an increase in diameter on follow-up imaging studies, the increase has been minimal. The objective of this paper is to report growth of four cavernous hemangiomas that were shown to have doubled to tripled in diameter on follow-up imaging studies done between 34 months and 10.5 years after the initial diagnosis. CONCLUSION: This report indicates that hepatic hemangiomas can grow significantly in diameter, although such growth is unusual. Despite the growth of the lesion, however, if the imaging features are characteristic of hemangioma an imaging diagnosis can still be made confidently.

Adult↗
PubMed1996

Stress proteins as molecular biomarkers for environmental toxicology.

Biomarkers are increasingly being used in environmental monitoring to provide evidence that organisms have been exposed to, or affected by, xenobiotic chemicals. Usually, these biomarkers rely on biochemical, histological, morphological, and physiological changes in whole organisms; however, changes at the cellular and molecular levels of organization, especially in nucleic acids and proteins, are increasingly being used to supplement these more traditional biomarkers. This chapter starts by giving a brief overview of biomarkers and some of the basic requirements for their effective use. Then stress-inducible proteins that are potentially useful as environmental biomarkers are explored, and some examples of their application as biomarkers and methods of detecting them are presented.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Resection of malignant primary liver tumors.

BACKGROUND: Malignant primary liver tumors are an uncommon and challenging surgical problem. In spite of multimodality therapies, surgical resection remains the mainstay of treatment and the most likely chance for cure. We reviewed the 13-year resection experience of a single surgeon at our institution to evaluate the results. METHODS: A retrospective review from July 1982 to June 1995 was performed for patients presenting with a diagnosis of primary liver cancer. Those undergoing resection of their primary liver tumors form the basis of this report. RESULTS: One hundred eighty-four patients with a diagnosis of primary liver cancer were seen at our institution. Of these, 43 patients underwent 46 resections of their cancers by a single surgeon. There were 22 females (51%) and 21 males (49%). The average age was 61 years with a median age of 63 years (range, 19-85 years). Tumors resected included 27 hepatomas, 16 cholangiocellular carcinomas, 1 carcinoid tumor, 1 low grade mucinous cystadenocarcinoma, and 1 cystadenocarcinoma. Resections were as follows: 9 right trisegmentectomies, 8 right lobectomies, 1 left trisegmentectomy, 4 left lobectomies, 7 left lateral segmentectomies, and 17 partial lobectomies. Major complications occurred in 11 patients (26%). There were 3 deaths, for a 30-day perioperative death rate of 7%. Of the 43 patients, 13 had follow-up of less than 12 months and 30 had follow-up for more than 1 year. The mean survival of the 30 patients who had their tumors resected and were followed up for more than 1 year was 27.2 months and the median survival was 21 months. The median survival of patients not undergoing resection was less than 6 months. The 1-, 2-, 3-, and 5-year survival rates were 57%, 52%, 40%, and 33%, respectively. CONCLUSIONS: Primary liver cancer can be treated by resection with acceptable results. This remains the standard treatment of any liver cancer. Survival rates of patients after resection are much better than survival rates of patients who do not undergo surgery.

Adult↗
PubMed1996

Pancreatitis caused by a gastric duplication communicating with an aberrant pancreatic lobe.

Developmental anomalies of the pancreas and its ductal drainage system are an important cause of pancreatitis. Patients with such anomalies require appropriate surgical intervention. This report concerns an uncommon foregut anomaly that causes pancreatitis. A 9-year-old girl had recurrent pancreatitis secondary to a gastric duplication communicating with an aberrant pancreatic lobe. Appreciation of the relevant anatomy led to successful surgical management of the pancreatitis.

Anastomosis, Roux-en-Y↗
PubMed1995

Spectroscopic characterization of tick anticoagulant peptide.

Tick anticoagulant peptide (TAP) is a disulfide rich potent inhibitor of factor Xa. Although this peptide is of potential clinical utility, very little is known about its higher order structure. Therefore, the secondary structure of recombinant TAP (rTAP) has been examined by circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopy. Both techniques suggest that rTAP is rich in beta-sheet structure. Disulfide bonds play a significant role in the folding and structural stability of rTAP. This is apparent from the resistance of rTAP to fluorescence-detected unfolding by guanidinium chloride (Gdn-HCl), unless disulfides are first reduced. The protein's tryptophan and tyrosine residues exhibit greater solvent exposure upon reduction of the cystines as indicated by fluorescence spectra and second derivative UV spectroscopy. A considerable amount of beta-structure appears to be retained after reduction of disulfides, although the CD spectrum manifests an increased amount of disordered structure in the reduced peptide. While rTAP does not bind the hydrophobic fluorescence probe 2-p-toludinylnaphthalene-6-sulfonate (TNS) at neutral or acidic pH, the reduced peptide binds TNS at pH 2.0 but not at pH 7.0. The secondary structure of the reduced peptide at pH 2 is, however, similar to that at pH 7 as judged by CD spectroscopy. The reduced form of rTAP at acidic pH thus resembles a molten globule-like state.

Arthropod Proteins↗
PubMed1995

Hydrocephalus and shunts in children with brain tumors.

Children with brain tumors are at risk for developing hydrocephalus necessitating placement of a permanent shunt catheter. As comprehensive, interdisciplinary, multispecialty care is required for these patients, the pediatric oncology nurse must become knowledgeable about caring for children with a shunt. This article focuses on the care of the pediatric neuro-oncology patient requiring shunting for hydrocephalus, including a review of cerebrospinal fluid flow and hydrocephalus, determinants of shunt placement, complications of ventriculoperitoneal shunts, and nursing considerations.

Brain Neoplasms↗
PubMed1994

Comparison of continuous ST-segment recovery analysis with methods using static electrocardiograms for noninvasive patency assessment during acute myocardial infarction. Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) 7 Study Group.

Continuous ST-segment recovery analysis and 5 static methods using ST-segment comparison between a pre- and post-treatment electrocardiogram were compared for their ability to predict infarct-related artery patency in 82 patients with acute myocardial infarction who underwent angiography a median of 124 minutes after onset of thrombolytic treatment. Accuracy at the moment of angiography was 85% (95% confidence interval [CI] 77% to 93%) for the continuous method, and 68% (CI 57% to 78%), 78% (CI 69% to 87%), 83% (CI 74% to 91%), 82% (CI 73% to 90%), and 80% (CI 71% to 89%) for the static methods. At the moment of angiography the most accurate static method and the continuous method agreed in patency assessment in 90% of the patients (CI 84% to 97%). Agreement was reduced to 83% (CI 75% to 91%) of patients when a patency assessment was performed earlier at 90 minutes after treatment onset, and was only 77% (CI 68% to 86%), at 60 minutes. Early disagreement was mainly seen when the continuous ST recording showed ST recovery from a delayed peak ST elevation after the pretreatment static electrocardiogram or when dynamic ST changes suggesting cyclic reperfusion occurred. Continuous ST-segment recovery analysis appears to be as accurate as the most accurate static methods. Continuously updated reference points appear to give important additional information when ST recovery follows a delayed peak ST elevation or when re-elevation occurs, suggesting cyclic flow changes. Such findings appear to affect about half of patients with acute myocardial infarction treated with intravenous thrombolysis, particularly early after administration of therapy.

Aged↗
PubMed1993

Partially structured self-associating states of acidic fibroblast growth factor.

A combination of near- and far-UV circular dichroism, Fourier-transform infrared spectroscopy, tryptophan fluorescence, size-exclusion chromatography, and a fluorescent extrinsic hydrophobic probe has been employed to characterize partially structured states of human recombinant acidic fibroblast growth factor (aFGF). At low pH, the addition of specific polyanionic ligands or moderate amounts of salts induces states with high secondary but low tertiary structure content. At neutral pH, intermediate amounts of chaotropic agents impose similar partially structured conformational states which also display noncooperative unfolding transitions. Kinetic evidence indicates that similar forms of the protein exist in the first few hundred milliseconds in the refolding pathway of aFGF. The kinetics of their formation appear to be temperature-independent, implying lack of an energy barrier, which is characteristic for further slow folding into the native state. Unlike the native and fully unfolded states, these partially structured conformations exhibit very low solubility, resulting in irreversible aggregation. Potential physiological implications of the existence of such "molten globule" states with regard to the growth factor's transport and biological activity are considered.

Chromatography, Gel↗
PubMed1993

Structure of synthetic peptide analogues of an eggshell protein of Schistosoma mansoni.

The peptide (Gly-L-Tyr-L-Asp-L-Lys-L-Tyr)6, referred to as F4-6, was synthesized as a model for a schistosome eggshell protein in which the Gly-Tyr-Asp-Lys-Tyr consensus sequence is repeated over 40 times. Analysis by CD, Fourier transform infrared spectroscopy, potentiometric and spectrophotomertric titrations, NMR, and molecular modeling suggests that F4-6 forms some type of left-handed structure. A likely possibility appears to be a left-handed alpha-helix stabilized by Lysi-Aspi +4 salt bridges and possibly Aspi-Tyri +4 hydrogen bonding and Tyr-Tyr interactions. Spectroscopic studies of a number of F4-6 analogues support this conclusion. For example, substitution of D-Ala for Gly produces a peptide with enhanced left-handed helical spectral characteristics, whereas an L-Ala substitution results in a peptide with minimal structure. These studies suggest that the F4 protein from Schistosoma mansoni may be the first example of a naturally occurring protein devoid of proline and carbohydrate that forms a left-handed helix composed of L-amino acids, although alternative forms of other left-handed structures have yet to be rigorously excluded.

Amino Acid Sequence↗
PubMed1993

Development of monoclonal antibodies for the detection of Mycoplasma pneumoniae.

Mycoplasma pneumoniae-specific monoclonal antibodies were constructed for the purpose of developing reagents for clinical diagnostics. The monoclonal antibodies, designated Mp2B12 and Mp3A11, recognize surface exposed antigens of 28 kDa and 170 kDa, respectively. Mp3A11 recognizes an epitope on a cytadhesin molecule, P1, which is not shared on the analogous cytadhesin of M. genitalium. Both monoclonal antibodies are capable of detecting 1 x 10(5) M. pneumoniae in a standard ELISA test.

Antibodies, Bacterial↗
PubMed1993

Endoscopic retrograde cholangiopancreatography after laparoscopic cholecystectomy.

We assessed the use of endoscopic retrograde cholangiopancreatography (ERCP) after laparoscopic cholecystectomy (LC) at our hepatobiliary referral center. This assessment included patients from outside institutions with post-LC problems. Between May 1990 and September 1992, we performed 522 LCs and 1,723 ERCP examinations. There were 78 patients who underwent 143 ERCP examinations after LC, 65% of whom were referred. ERCP findings were categorized as follows: normal results (8%), problems inherent to stone disease (65%), and iatrogenic injury (27%). The types of inherent problems were common bile duct (CBD) stones, pancreatitis, and papillary stenosis/microlithiasis. Within the CBD stone group, 5 of 26 patients also had papillary stenosis, and, within the pancreatitis group, 9 of 11 patients also had papillary stenosis, making papillary stenosis the most frequent observation (55%). Almost all of these patients (96%) required endoscopic papillotomy for successful treatment. The iatrogenic injury group was comprised of 21 patients, 16% of whom had cystic duct leak and 84% of whom had CBD injury. These patients required a variety of endoscopic procedures including endoscopic papillotomy (67%), CBD endoscopic stenting (76%), percutaneous drainage of biloma (29%), and percutaneous transhepatic biliary drainage (24%). Open surgical procedures after endoscopic assessment or treatment were required in only three patients in the iatrogenic group and in none in the inherent group. At this time, long-term follow-up is not possible with regard to biliary stricture. We conclude that the majority of problems after LC are either due to papillary stenosis/microlithiasis with or without CBD stones or to biliary injury. Both can be successfully diagnosed and treated with endoscopic techniques.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1993

Diagnosis and staging of pancreatic adenocarcinoma with dynamic computed tomography.

We assessed the accuracy of dynamic contrast-enhanced computed tomography (CT) in the diagnosis and staging of 213 patients with pancreatic carcinoma and compared it with the accuracy of angiography and surgery. A correct CT diagnosis of pancreatic carcinoma was made in 207 of 213 (97%) patients. Tumors were located in the pancreatic head in 64%, the body in 22%, and the tail in 10%, and enlarged the pancreas diffusely in 4%. CT staged 25 (12%) patients as having potentially resectable tumors and 188 (88%) as having unresectable tumors on the basis of local extension (72%), contiguous organ invasion (43%), vascular invasion (82%), and distant metastases (50%). Compared with angiography in 60 patients, CT detected vascular invasion missed on angiography in 20%, and angiography detected invasion missed by CT in 5%. In these latter cases, other CT criteria of unresectability were present, and angiography provided no significant staging information. Compared with surgery in 71 patients, CT accurately predicted unresectable tumors in 100% of patients and resectable tumors in 72% of patients. Eleven of the patients with CT-resectable tumors underwent resection. Median survival was 22.7 months, with four patients alive at a median of 15.5 months postoperatively. Palliative resections were performed in six patients, and median survival was 14.4 months.

Adenocarcinoma↗