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S Wallace

Publications and source records attributed to S Wallace.

At least 145 records · Page 8Linked to original sources
PubMed1994

Preparation, characterization, and evaluation of ioxilan carbonate particles for computed tomography contrast enhancement of liver.

RATIONALE AND OBJECTIVES: To prepare and characterize a new particulate contrast medium, cyclic carbonate of ioxilan (IX-C) particles, as a macrophage imaging agent for computed tomography (CT) enhancement of the liver. METHODS: Cyclic carbonate of ioxilan was synthesized from ioxilan, a nonionic water-soluble contrast agent. The IX-C particles prepared by a solvent extraction-evaporation method were characterized by size distribution, degradability, suspension stability, and median lethal dose. Pharmacokinetics of IX-C particles and their effectiveness in enhancing liver attenuation and in detecting hepatic tumors were evaluated using normal and VX2-tumor-bearing rabbits. RESULTS: The IX-C particles were biodegradable, with ioxilan and carbon dioxide as the degradation products. The particles had an average size of 1 to 2 microns and were stable in saline suspension. The median lethal dose determined for IX-C particles was 2.6 and 3.1 g/kg body weight for female and male rabbits, respectively. A dose of 200 mg iodine/kg body weight caused an increase of 38 Hounsfield units in liver attenuation. In rabbit, hepatic clearance of the contrast medium occurred in 2 days. A tumor barely visible in precontrast scans could be detected after contrast injection. CONCLUSIONS: Development of particulate contrast medium from nonionic contrast agents represents a new approach. Ioxilan carbonate particles have suitable physicochemical properties that warrant further studies before clinical evaluation.

Animals↗
PubMed1994

LATCH: a breastfeeding charting system and documentation tool.

Nurses most often use a subjective "well/fair/poor" system to assess and document breastfeeding. LATCH is a breastfeeding charting system that provides a systematic method for gathering information about individual breastfeeding sessions. The system assigns a numerical score, 0, 1, or 2, to five key components of breastfeeding. Each letter of the acronym LATCH denotes an area of assessment. "L" is for how well the infant latches onto the breast. "A" is for the amount of audible swallowing noted. "T" is for the mother's nipple type. "C" is for the mother's level of comfort. "H" is for the amount of help the mother needs to hold her infant to the breast. The system is visually represented in the same form as the Apgar scoring grid, and the numbers are handled in the same way. With the LATCH system, the nurse can assess maternal and infant variables, define areas of needed intervention, and determine priorities in providing patient care and teaching.

Breast Feeding↗
PubMed1994

Polyclonal and monoclonal antibody and PCR-amplified small-subunit rRNA identification of a microsporidian, Encephalitozoon hellem, isolated from an AIDS patient with disseminated infection.

Microsporidia are primitive, spore-forming, mitochondria-lacking, eukaryotic protozoa that are obligate intracellular parasites. They are known to parasitize almost every group of animals including humans. Recently, microsporidia have increasingly been found to infect patients with AIDS. Five genera (Encephalitozoon, Enterocytozoon, Nosema, Septata, and Pleistophora) of microsporidia are known to infect humans. Enterocytozoon organisms cause gastrointestinal disease in a majority of AIDS patients with microsporidiosis. However, a smaller, but an expanding, number of patients with AIDS are being diagnosed with ocular and disseminated infection with Encephalitozoon hellem. Although microsporidial spores can be identified in clinical samples by a staining technique such as one with Weber's chromotrope stain, identification to the species level is dependent on cumbersome and time-consuming electron microscopy. We have recently isolated and established in continuous culture several strains of E. hellem from urine, bronchoalveolar lavage, and sputum samples from AIDS patients with disseminated microsporidiosis. We developed polyclonal and monoclonal antibodies and PCR primers to a strain of E. hellem that can be used successfully to identify E. hellem from other species of microsporidia either in clinical specimens or in cultures established from clinical specimens. Since patients infected with Encephalitozoon spp. are known to respond favorably to albendazole, identification of the parasite to the species level would be invaluable in the treatment of disseminated microsporidiosis.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Pathways of nodal metastasis from pelvic tumors: CT demonstration.

Although the normal pathways of lymphatic drainage from the pelvic organs have been well described in the anatomy literature, the pathways of nodal metastasis from individual pelvic neoplasms are not well illustrated in the imaging literature. The authors retrospectively reviewed computed tomographic scans of the abdomen and pelvis in patients with various pelvic neoplasms, including those of the ovary, testis, prostate, cervix, bladder, anorectum, and other sites, to define the pathways of nodal metastasis. In most patients, pathways of nodal metastasis correlated well with the normal lymphatic pathways described in the anatomy literature, including the superficial inguinal pathway; the anterior, lateral, hypogastric, and presacral routes of the pelvic pathway; and the paraaortic pathway. However, there also were various uncommon pathways of nodal metastasis, such as metastasis along the gonadal vessels, mesenteric and mesocolic nodes, posterior iliac crest nodes, and inferior phrenic nodes. Understanding these common and uncommon lymphatic pathways of metastasis will help radiologists detect disease spread from pelvic tumors.

Humans↗
PubMed1993

A phase I-II trial of mitoxantrone by hepatic arterial infusion in patients with hepatocellular carcinoma or colorectal carcinoma metastatic to the liver.

BACKGROUND: Mitoxantrone is an anthraquinone derivative that has demonstrated encouraging preclinical and clinical activity against a variety of human carcinoma cell lines and malignancies. Three Phase II studies of systemically administered mitoxantrone in patients with colorectal carcinoma failed to demonstrate any therapeutic activity, as did four Phase II studies of intravenous mitoxantrone in hepatocellular carcinoma. Two additional trials demonstrated limited activity when administered intravenously to patients with hepatocellular carcinoma. However, because this drug exhibits a steep dose-response curve, a Phase I-II trial of mitoxantrone by hepatic arterial infusion was initiated. METHODS: Patients with hepatocellular carcinoma and metastatic colorectal carcinoma with liver only or liver-predominant disease were eligible for therapy. All patients underwent the placement of a percutaneous hepatic arterial catheter before each course of therapy, and the first cohort of patients was treated at 10 mg/m2/course on day 1 on a 28-day cycle. Dosages were escalated in increments of 2 mg/m2/course based on side effects and tolerance. RESULTS: Twenty-eight patients with bidimensionally measurable unresectable, liver-predominant disease were entered into this trial. The therapy was well tolerated, with only 5 courses of 55 being complicated by neutropenia and none associated with fever. Only one patient required a dosage reduction on the basis of toxicity (neutropenia). No complete or partial responses were observed. CONCLUSION: These data are consistent with a lack of therapeutic activity of mitoxantrone when administered by hepatic arterial infusion for the treatment of hepatocellular carcinoma or metastatic colorectal cancer.

Adult↗
PubMed1993

Intraoperative long-latency reflex activity in idiopathic scoliosis demonstrates abnormal central processing. A possible cause of idiopathic scoliosis.

Segmental reflex regulation in 37 patients with idiopathic scoliosis and 8 patients with nonidiopathic scoliosis was studied by recording evoked reflex muscle potentials from four muscle groups in each lower extremity during partial neuromuscular blockade. Effects on reflex activity mediated through descending systems arising in the brain stem were investigated by recording from proximal-distal and flexor-extensor muscles. Ipsilateral and contralateral long-latency complex polysynaptic activity was present in all 37 patients with idiopathic scoliosis. This reflex activity was absent in eight nonidiopathic scoliosis patients. Long-latency reflex activity may represent segmental disinhibition. The presence of long-latency reflex activity in patients with idiopathic scoliosis and the absence of this activity in nonidiopathic scoliosis patients with curves of equal magnitude demonstrates that the curve per se is not responsible for the activity. This would imply that abnormal reflex processing may play a role in the development of the spinal deformity in patients with idiopathic scoliosis.

Adolescent↗
PubMed1993

Durable hepatic tumor regression after arterial chemoembolization-infusion in patients with islet cell carcinoma of the pancreas metastatic to the liver.

BACKGROUND: Islet cell carcinoma of the pancreas is a neuroendocrine tumor often presenting with left upper quadrant mass and radiographic evidence of liver metastases. Because survival among these patients is determined largely by the pace of metastatic events in the liver, significant palliation may be achieved by regional hepatic therapy. METHODS: Five patients with islet cell carcinoma of the pancreas metastatic to the liver (four nonfunctional, one gastrin producing), were treated by hepatic arterial chemoembolization-infusion consisting of a mixture of polyvinyl alcohol sponge (150 mg) and cisplatin (150 mg) followed by 2-hour intraarterial infusion of vinblastine (10 mg/m2). Each patient received two such treatments, 1 month apart, requiring 3 to 6 days of hospital admission. RESULTS: Significant tumor regression (> 50%) was observed in four of five patients, lasting from 8 to 44 months. Toxicity was limited to right upper quadrant pain, paralytic ileus requiring nasogastric suction for 24 to 72 hours, transient, mild bilirubinemia and liver enzyme elevation, hypomagnesemia and hypokalemia, and occasionally, moderate, self-limiting granulocytopenia. CONCLUSIONS: This preliminary, albeit limited, experience with hepatic chemoembolization-infusion in patients with islet cell carcinoma metastatic to the liver emphasizes the high incidences of durable tumor regression that can be achieved with minimal iatrogenic intervention.

Adenoma, Islet Cell↗
PubMed1993

Intraoperative radiographs to confirm the adequacy of lymph node resection in patients with suspicious lymphangiograms.

Between June 1991 and October 1992, we used presurgery lymphangiograms and intraoperative radiographs to identify and remove suspicious nodes in the pelvic and para-aortic chains of 19 patients with bulky pelvic cancers. Surgery comprised extraperitoneal exploration using a midline vertical or paramedian "J" incision. After grossly enlarged nodes were removed, an intraoperative anterior-posterior (AP) abdominal radiograph was obtained. The exposure field approximated the 24-hr delay AP LAG radiograph. Both films were compared in the operating room to confirm removal of abnormal nodes. Initial resection removed all suspicious nodes in 16 of 19 cases. Additional dissection resulted in successful node excision in the other 3 patients. Most of these "missed" nodes were behind or between vessels. The median number of nodes sampled was 15 (range 2-47). Bilateral sampling was performed in 15 cases. Metastatic tumor was present in 14 patients (74%) who had from 1 to 8 positive nodes. Of the 5 negative specimens, all contained lipogranulomata; two had extensive fatty replacement, 2 contained Müllerian inclusions, and 1 had reactive follicular hyperplasia which could be accountable for the radiographic abnormalities. Extracapsular extension was noted in 12 of 14 metastatic samplings. Radiotherapeutic treatment planning was then tailored to lymph node status and the location of positive nodes. Combined use of preoperative LAG and intraoperative films is useful in ensuring that complete resection of abnormal nodes has been accomplished. Whether removal of gross lymph node metastases enhances survival requires further study.

Adult↗
PubMed1993

Hepatocellular carcinoma with or without cirrhosis: a comparison of CT and angiographic presentations in the United States and Japan.

We compared the computed tomographic (CT) and angiographic presentations of hepatocellular carcinoma (HCC) with or without cirrhosis in the United States and Japan. Tumors in the United States were advanced and less frequently associated with liver cirrhosis (association of cirrhosis: United States 56.2%, Japan 91.0%. In patients with cirrhosis, the size of the tumor tended to be smaller, and nodular tumors (single or multiple) were frequent. In early stage of HCCs with cirrhosis, tumors were hypovascular without a capsule. In advanced stage, tumors were hypervascular and a capsule was frequently observed around the tumor both with CT and angiography. HCCs without cirrhosis were seen in younger patients. These tumors were large at the time of diagnosis. A massive or diffuse mass without a capsule was frequently seen. Most tumors were hypodense on precontrast CT and hypervascular on angiography. Lymph node enlargement was significantly frequent. The radiological characteristics of HCC in both countries were significantly different depending upon associated cirrhosis, as well as the time of the diagnosis.

Adult↗
PubMed1993

Thymine ring saturation and fragmentation products: lesion bypass, misinsertion and implications for mutagenesis.

We have used thymine glycol and dihydrothymine as representative ring saturation products resulting from free-radical interaction with DNA pyrimidines, and urea glycosides and beta-ureidoisobutyric acid (UBA) as models for pyrimidine-ring fragmentation products. We have shown that thymine glycol and the ring-fragmentation products urea and beta-ureidoisobutyric acid, as well as abasic sites, are strong blocks to DNA polymerases in vitro. In contrast, dihydrothymine is not a block to any of the polymerases tested. For thymine glycol, termination sites were observed opposite the putative lesions, whereas for the ring-fragmentation products, the termination sites were primarily one base prior to the lesion. These and other data have suggested that thymine glycol codes for an A, and that a base is stably inserted opposite the damage, whereas when a base is inserted opposite the non-coding lesions, it is removed by the 3-->5 exonuclease activity of DNA polymerase I. Despite their efficiency as blocking lesions, thymine glycol, urea and UBA can be bypassed at low frequency in certain specific sequence contexts. When the model lesions were introduced individually into single-stranded biologically active DNA, we found that thymine glycol, urea, beta-ureidoisobutyric acid, and abasic sites were all lethal lesions having an activation efficiency of 1, whereas dihydrothymine was not. Thus the in vitro studies predicted the in vivo results. When the survival of biologically active single-stranded DNA was examined in UV-induced Escherichia coli cells where the block to replication was released, no increase in survival was observed for DNA containing urea or abasic sites, suggesting inefficient bypass of these lesions. In contrast, beta-ureidoisobutyric acid survival was slightly enhanced, and transfecting DNA containing thymine glycols was significantly reactivated. When mutation induction by unique lesions was measured using f1-K12 hybrid DNA containing an E. coli target gene, thymine glycols and dihydrothymine were found to be inefficient as premutagenic lesions, suggesting that in vivo, as in vitro, they primarily code for A. In contrast, urea and beta-ureidoisobutyric acid were efficient premutagenic lesions, with beta-ureidoisobutyric acid being about 4-5-fold more effective than urea glycosides, which have approximately the same rate of mutation induction as abasic sites from purines. Sequence analysis of the mutations resulting from these ring-fragmentation products shows that the mutations produced are both lesion and sequence context dependent. The possible roles that bypass efficiency and lesion-directed misinsertion might play in mutagenesis are discussed.

Base Sequence↗
PubMed1993

An epilepsy needs document.

Services for epilepsy in the UK are poor in quality, fragmentary and poorly organized. We attempt to define and quantify the scope, content and standards of medical, paramedical and nursing services required, from primary health care to specialist centres. This document has been approved by the Joint Epilepsy Council of Great Britain and Ireland, representing all major patient organizations and care providers.

Cross-Sectional Studies↗
PubMed1993

Pharmacokinetics of single intravenous and single and multiple dose oral administration of rifampin in mares.

The disposition of rifampin in six healthy mares after single intravenous (i.v.) and oral (p.o.) doses and after seven oral doses of 10 mg/kg administered twice a day was investigated using a high performance liquid chromatographic (HPLC) method. Pharmacokinetic variables for rifampin determined using the HPLC method were comparable to variables reported from earlier studies utilizing a microbiological assay. Desascetylrifampin, a major metabolite of the parent compound, could not be detected in the serum but was detected at low concentrations in urine. Mean trough concentrations of rifampin increased from the first to the second dose of the multiple dose oral study and then remained unchanged through 72 h. At 84 h after the first dose (i.e. 12 h after the final dose) the rifampin concentration was significantly decreased (P = 0.001). The harmonic mean of the half-life of rifampin decreased significantly from 13.3 h after a single oral dose of 7.99 h after the seventh oral dose. The mean serum protein binding of rifampin over the concentration range of 2-20 micrograms/ml was 78%. Mean trough serum concentrations of unbound rifampin after multiple oral doses ranged from 0.67 micrograms/ml at 24 h to 0.40 micrograms/ml at 72 h. The mean unbound serum rifampin concentration at 84 h (i.e., 12 h after the final dose) was 0.30 micrograms/ml. Trough concentrations and the 84-h sample concentration of unbound rifampin exceeded the minimum inhibitory concentration for most gram positive bacterial isolates from horses reported in this study. All organisms with minimum inhibitory concentrations less than 0.125 micrograms/ml were considered susceptible. Based on the pharmacokinetics of rifampin after p.o. administration, we concur with the current dosage recommendation of 10 mg/kg twice a day by mouth. At this dose, most streptococci, Rhodococcus equi, and coagulase-positive staphylococci would be considered susceptible to rifampin.

Administration, Oral↗
PubMed1993

Cooperation of structural proteins during late events in the life cycle of polyomavirus.

The polyomavirus minor late capsid antigen, VP2, is myristylated on its N-terminal glycine, this modification being required for efficient infection of mouse cells. To study further the functions of this antigen, as well as those of the other minor late antigen, VP3, recombinant baculoviruses carrying genes for VP1, VP2, and VP3 have been constructed and the corresponding proteins have been synthesized in insect cells. A monoclonal antibody recognizing VP1, alpha-PyVP1-A, and two monoclonal antibodies against the common region of VP2 and VP3, alpha-PyVP2/3-A and alpha-PyVP2/3-B, have been generated. Reactions of antibodies with antigens were characterized by indirect immunofluorescence, immunoprecipitation, and immunoblot analysis. Immunofluorescent staining of mouse cells infected with polyomavirus showed all antigens to be localized in nuclei. When the late polyomavirus proteins were expressed separately in insect cells, however, only VP1 was efficiently transported into the nucleus; VP2 was localized discretely around the outside of the nucleus, and VP3 exhibited a diffused staining pattern in the cytoplasm. Coexpression of VP2, or VP3, with VP1 restored nuclear localization. Immunoprecipitation of infected mouse cells with either anti-VP1 or anti-VP2/3 antibodies precipitated complexes containing all three species, consistent with the notion that VP1 is necessary for efficient transport of VP2 and VP3 into the nucleus. Purified empty capsid-like particles, formed in nuclei of insect cells coinfected with all three baculoviruses, contained VP2 and VP3 proteins in amounts comparable to those found in empty capsids purified from mouse cells infected with wild-type polyomavirus. Two-dimensional gel analysis of VP1 species revealed that coexpression with VP2 affects posttranslational modification of VP1.

Amino Acid Sequence↗
PubMed1993

In vivo microscopy of hepatic tumors in animal models: a dynamic investigation of blood supply to hepatic metastases.

The dynamics of blood circulation in three experimental animal models of hepatic metastasis were investigated with in vivo microscopy. It was demonstrated that the tumor vasculature communicated with the portal venules and hepatic sinusoids that surrounded the tumors. The hepatic artery was not seen to connect to the tumors directly. However, it was demonstrated that arterial blood entered tumors through the portal venules and that the hepatic arterial flow entered the tumor without resistance, while blood from the portal vein met great resistance at the tumor border, with only small amounts entering the tumor. Interruption of either the hepatic artery or the portal vein did not result in cessation of the blood circulation in hepatic tumors. A reciprocal relationship between the hepatic arterial and portal venous supplies to hepatic tumors was suggested, and it was hypothesized that arterioportal communications play an important role in the arterial and portal venous supply of blood to hepatic tumors. A comprehensive understanding of the blood supply of hepatic tumors is important for improving clinical treatment of hepatic tumors.

Adenocarcinoma↗
PubMed1993

An anatomical study of the tarsal tunnel using low pressure compartmental infusion.

The anatomy of the tarsal tunnel is demonstrated using a low-pressure compartmental infusion technique. This is done by infusing colored radiopaque contrast material into three fresh cadaveric specimens. Thin section photography and computed tomography are then used to identify the boundaries and contents of the tarsal tunnel as it traverses the ankle, hindfoot, and midfoot. The tarsal tunnel is shown to communicate proximally with the deep posterior compartment of the leg and distally with the intermediate compartment of the forefoot. The relationships of the structures contained within the tarsal tunnel are shown in detail.

Ankle↗
PubMed1993

Lymphography for staging lymphomas: is it still a useful procedure?

OBJECTIVE: The purpose of this study was to determine the current value of lymphography in a series of previously untreated patients with Hodgkin's and non-Hodgkin's lymphoma seen at the M. D. Anderson Cancer Center over a 1-year period. MATERIALS AND METHODS: From September 1989 through August 1990, 313 previously untreated patients with lymphoma were seen at our institution. In 221 of these, lymphography and CT were performed for abdominal staging. These studies were reviewed to determine if the examinations were complementary, or if the results of one or the other changed the staging in a significant number of patients. Staging was based on clinical findings, as laparotomies are rarely performed at this time. RESULTS: Lymphograms were abnormal and CT scans were normal in two patients with Hodgkin's disease and in two with non-Hodgkin's lymphomas. Biopsy proof of nodal disease was not available for any of these, but the nodes did not change after therapy in three patients. The other patient was seropositive for HIV, and HIV disease itself can cause nodal abnormalities. In one patient with Hodgkin's disease and 12 with non-Hodgkin's lymphoma, lymphograms were normal and CT scans were abnormal, showing enlarged nodes and/or abnormal architecture. CT scans obtained after therapy showed regression of nodal and extranodal masses. CONCLUSION: It was concluded that lymphographic findings did not significantly contribute to staging in these patients. This departure from previous experience may be due to improved state-of-the-art CT. In addition, the use of a combination of chemotherapy and radiation therapy to treat the lymphomas has increased, diminishing the need for detection of subtle nodal changes.

Hodgkin Disease↗