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Biomedical subjects

W O'Brien

Publications and source records attributed to W O'Brien.

At least 37 records · Page 2Linked to original sources
PubMed1991

Primary leiomyosarcoma of adrenal gland. Case report with immunohistochemical and ultrastructural study.

A primary leiomyosarcoma of the right adrenal gland is reported in a 49-year-old male who presented with progressive flank pain. This is the second case in the English language literature and the first to have documentation of malignant behavior. The tumor measured 11 cm in diameter and showed marked necrosis with prominent mitotic activity (average 15 per 10 high-power fields). Smooth muscle differentiation was apparent ultrastructurally and confirmed by positive immunostaining for muscle-specific and alpha-smooth muscle actin. Bony metastases developed; following palliative treatment with radiation and chemotherapy, the patient is alive with tumor 9 months later. Origin from smooth muscle associated with the central adrenal vein or its tributaries is proposed.

Adrenal Gland Neoplasms↗
PubMed1991

Identification of human immunodeficiency virus envelope gene sequences influencing viral entry into CD4-positive HeLa cells, T-leukemia cells, and macrophages.

Infectious recombinant viruses were constructed from three molecularly cloned human immunodeficiency virus (HIV) strains varying in cell tropism. All recombinants showed a high infectivity titer on phytohemagglutinin-stimulated normal T lymphocytes. However, a 120-bp region of the envelope gene including the area of the V3 hypervariable loop was found to influence infectivity titer on both clone 1022 CD4-positive HeLa cells and CD4-positive CEM leukemia cells. Infectivity for macrophages was more complex. All viruses replicated in macrophages to a low level, but viral sequences both inside and outside the V3 loop region influenced the efficiency of replication. Two experiments showed that the mechanism of restriction of infection of 1022 cells by HIV strain JR-CSF was related to lack of virus entry. First, productive virus infection occurred after transfection of 1022 cells with viral plasmid DNA. Second, the nonpermissive HIV strain JR-CSF could infect 1022 cells when pseudotyped with the envelope of other retroviruses, including human T-cell leukemia virus type I (HTLV-I), HTLV-II, and amphotropic murine leukemia virus. These results demonstrate the possibility that unexpected cell types might be infected with HIV in human patients coinfected with HIV and HTLV-I or HTLV-II.

Amino Acid Sequence↗
PubMed1990

Endoscopic stent configuration and bile flow rates in a variable diameter bile duct model.

Endoscopically placed biliary stents are used in the treatment of biliary strictures and obstruction. Patency of the stent is related to bile flow rate through the stent. The purpose of this study was to examine the influence of stent diameter, configuration, and common duct diameter on bile flow rates. Flow rates were examined in straight and pigtail stents, 7 Fr and 10 Fr, and in a 1 cm and 2.3 cm diameter CBD model. Bile-flow rates were greater in the straight and 10 Fr stents. Bile-duct diameter had no influence on flow rate in pigtail stents. Though flow rates decreased with straight stents in bile ducts of increasing diameter, the absolute flow rates always remained greater in the straight stents when compared to the pigtail stents. We conclude that straight stents, because of greater flow rates, are to be preferred over pigtail stents for the treatment of biliary obstruction in dilated and nondilated systems.

Bile Ducts↗
PubMed1988

Scrotal enlargement following inguinal herniorrhaphy: ultrasound evaluation.

Although sonography has become an established modality in the evaluation of acute and chronic scrotal abnormalities, its role in the post-herniorrhaphy patient with scrotal swelling has not yet been defined. We present 5 patients with immediate and delayed complications of herniorrhaphy in which sonography provided useful clinical information. Immediate complications included scrotal hematomas, scrotal wall and septal thickening, epididymitis, and testicular displacement. Delayed complications included an infected hydrocele demonstrating a fluid-debris level. The etiology of scrotal swelling in postherniorrhaphy patients can be determined with sonography.

Edema↗
PubMed1988

Intraoperative assessment of myocardial revascularisation for the relief of ischaemia using monophasic action potential recordings.

We have been concerned with developing a method of assessing regional myocardial perfusion which is simple, quick and without hazard to the patient. Monophasic action potential (MAP) recordings provide a highly sensitive measure of localised myocardial ischaemia. We have developed a hand-held pressure contact silver/silver chloride electrode for recording MAP signals from the left ventricular epicardium. The design enables it to slide within the pericardium on the left ventricle/epicardium with minimal displacement of the heart. Three protocols were adopted providing different permutations of atrial pacing and graft occlusion. Protocol 1: after discontinuing bypass, atrial pacing was established. After 90 s, all grafts were occluded for a period of 90 s. Protocol 2: after discontinuing bypass, all grafts were occluded for 90 s in the absence of pacing. Protocol 3: atrial pacing was established for 60 s before grafting and bypass and repeated subsequent to grafting and discontinuing bypass. Our results show that the most promising method is protocol 3. The most important results were that when heart rate is taken into account, the ischaemic changes in the MAP were significantly less impressive (P less than 0.05) following grafting. With further refinement, this technique may be applicable to the assessment of individual grafts.

Action Potentials↗
PubMed1988

Monophasic action potentials at discontinuation of cardiopulmonary bypass: evidence for contraction-excitation feedback in man.

Mechanical dysfunction is the strongest predictor of sudden cardiac death due to arrhythmia. Contraction-excitation feedback whereby changes in myocardial length/tension influence the time course of repolarization and excitability would provide a possible mechanism. Such a relationship has been shown in animals but has yet to be demonstrated in man. A useful model for studying this relationship is provided by the process of weaning off cardiopulmonary bypass after routine coronary artery surgery. During this weaning period of approximately 1 min, the heart is converted from being partially empty and flaccid (i.e., a "nonworking" state) to being filled and stretched to support the circulation (i.e., a "working" state). Monophasic action potentials (MAPs) were recorded from the left ventricular epicardium as a measure of repolarization time in 16 patients at discontinuation of cardiopulmonary bypass. Systolic pressure was recorded from the radial artery line. Measurements were made at three stages that related to different dynamic states of the heart: (1) starting to come off bypass ("minimally working"), defined as the time of first appearance of an inflection on the arterial pressure trace indicating the start of left ventricular ejection and valve opening, when arterial pressures represent left ventricular pressure, (2) half off bypass ("partially working"), and (3) off bypass ("wholly working"). During the process of discontinuing bypass MAP duration shortened, while systolic pressure increased. MAP duration at 90% and 60% repolarization (MAP D90, MAP D60) decreased from 288.0 +/- 29.5 msec (mean +/- SEM) and 235.0 +/- 27.9 msec in the minimally working heart to 274.5 +/- 30.2 msec and 224.2 +/- 27.3 msec in the partially working heart (p less than .001), with a subsequent decrease to 261.0 +/- 28.8 and 214.0 +/- 28.7 when the heart was wholly working (p less than .001). Systolic pressure increased from 54.1 +/- 9.3 mm Hg in the minimally working heart to 65.9 +/- 13.8 mm Hg in the partially working heart (p less than .001) and subsequently increased to 75.5 +/- 13.3 mm Hg when the heart was wholly working (p less than .001). Mean heart rates did not change significantly. A strong correlation was obtained between absolute MAP duration and systolic pressure. Regression analysis revealed: MAP D90 vs systolic pressure (p less than .001) and MAP D60 vs systolic pressure (p less than .01).(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1987

Ultrasonic assessment of skin and wounds with the scanning laser acoustic microscope.

The aim of the present study was to test the hypothesis that ultrasonic propagation properties in skin and wound tissue would correlate with material properties such as collagen content, water content, and tensile strength of those tissues. Both ultrasonic speed and ultrasonic attenuation coefficient were directly correlated with tissue collagen content, [r = 0.80 and r = 0.56, respectively (p less than 0.001)]. In addition, ultrasonic speed and attenuation coefficient were inversely correlated with tissue water content, [r = -0.57 and r = -0.73, respectively (p less than 0.001)]. Tensile strength also correlated very significantly with ultrasonic speed (r = 0.90, p less than 0.001), and significantly with attenuation coefficient (r = 0.58, p less than 0.001). The results demonstrate the feasibility of using ultrasound for noninvasively determining the material properties of biologic tissues including healing cutaneous wounds.

Animals↗
PubMed1986

Use of monophasic action potential recordings during routine coronary-artery bypass surgery as an index of localised myocardial ischaemia.

In 8 patients undergoing routine coronary-artery bypass surgery, monophasic action potentials (MAPs) were measured by means of a hand-held pressure contact electrode to provide an index of local ischaemic changes. 4 patients received left internal mammary anastomoses (LIMA), and there were a total of 27 saphenous vein grafts (SVG). After completion of all grafts blood-flow to the myocardium was reduced for 90 s by means of different permutations of SVG and LIMA occlusion, either on or off bypass. In all patients MAPs indicated typical ischaemic changes. The high sensitivity of the method enables the study to be completed quickly and without hazard to the patient. The technique provides a new means to assess local ischaemia, the viability of specific areas of myocardium, and the efficiency of individual grafts during surgery.

Action Potentials↗
PubMed1986

Suppression of tumor growth by senescence in virally transformed human fibroblasts.

Normal human cells whether embryonic, neonatal, or adult are resistant to experimentally induced tumorigenesis in contrast to rodent or chicken cells. We showed previously that neither transformation with simian virus 40 DNA nor transfection with human mutant HRAS DNA immortalized FS-2 cells (diploid, neonatal human fibroblasts). Further, tumorigenicity was not induced, despite expression of the respective transforming gene products tumor (T) antigen or p21. Here we describe treatment of FS-2 and FSSV cells with baboon endogenous virus pseudotyped Kirsten murine sarcoma virus. FSSV cells were derived from individual foci of simian virus 40-transformed FS-2 cells. The retrovirus-treated FS-2 cells (called FSK) appeared heavily granulated and expressed viral p21 but senesced during passage in culture and were not tumorigenic. The retrovirus-treated FSSV-27 cells (called FSVK-27) expressed simian virus 40 tumor antigen, had elevated levels of viral p21 protein, and formed transient tumors in nude mice. Whether grown in culture or explanted from small tumors, the FSVK-27 cells senesced. The FSVK-46 cells senesced before tumor growth occurred. On the contrary, Kirsten murine sarcoma virus (baboon endogenous virus) treatment of immortalized nontumorigenic human fibroblasts expressing simian virus 40 tumor antigen (Va2 cells) led to consistent tumor formation. The results illustrate the importance of senescence in restricting the tumor-forming ability of human cells.

Animals↗
PubMed1986

Effects of two fluoride gels on fluoride uptake and phosphorus loss during artificial caries formation.

Blocks of human enamel were cycled through a demineralization--F-treatment-remineralization procedure and then analyzed for fluoride and the presence of caries-like lesions. Treatments with a sodium fluoride gel (5000 ppm F) increased the enamel fluoride concentration to 6500 ppm F, whereas a stannous fluoride gel (1000 ppm F) increased enamel fluoride to about 1200 ppm F. Although a control treatment (water) allowed caries-like lesions to form, as observed by microradiography, no lesions were found in either of the fluoride-treated groups. When the experiment was repeated with radioactive teeth, mineral loss, as determined by release of 32P, was again greatest in the water-treated control group, but some loss was observed in the fluoride treatment groups. The least loss was found in the sodium fluoride group. It was concluded that the fluoride treatments not only increased enamel resistance but also enhanced remineralization so that calcium phosphate was replaced during the subsequent remineralization phase. Because of the probability that stannous ions were deposited during the stannous fluoride treatments, some of the apparent calcium phosphate re-deposition in this group was probably stannous compounds.

Absorptiometry, Photon↗
PubMed1985

Neuropsychological impairment and behavioral limitations exhibited within an alcohol treatment program.

The present study investigated the generalizability of neuropsychological test data to behavioral problems/limitations exhibited by alcoholics within an inpatient treatment program. Ratings supplied by alcohol counselors of problematic behaviors were used to form two groups (N = 40) representing behaviorally impaired (B1) and behaviorally unimpaired (BU) alcoholics. The neuropsychological performance of BI subjects was found to be impaired, relative to BU subjects, on composite measures of motor skill, problem solving, psychomotor speed, and memory. BI subjects, relative to the BU group, were also found to have significantly longer histories of alcoholism, more frequent neurological examination abnormalities, and higher incidences of suboptimal nutrition. Taken as a whole, these data suggest that neuropsychological measures may have some potential for assisting in the generating of valid inferences regarding both underlying cerebral pathology and the behavioral consequences of such as expressed within the alcohol treatment milieu.

Adult↗
PubMed1984

Health effects associated with exposure to radioactively contaminated gold rings.

This study was designed to assess the health risks associated with exposure to radioactively contaminated gold rings. A group of 135 exposed individuals, who were identified through a statewide jewelry screening program, were studied to determine the frequency of carcinoma and other skin problems on the ring finger. Severity of skin problems increased with increasing length of wear. Forty-one of the exposures were associated with mild to severe skin problems. Nine of the individuals studied were diagnosed as having histologically confirmed squamous cell carcinomas at the site of exposure. The incidence of skin cancer on the ring finger was eleven times that expected for men and forty-five times that expected for women. These data indicate that physicians who have patients with skin lesions of the ring finger should be aware of the possibility of exposure to a radioactive gold ring.

Adult↗
PubMed1983

Roentgenographic findings during auranofin treatment.

Roentgenograms of hands and wrists from rheumatoid arthritis patients treated with auranofin for 12 and 24 months were scored for severity of erosive disease. Scores were analyzed by a method in which a calculated mean annual rate of erosion prior to treatment was compared with the annualized rate during therapy. The original films from a previous Myochrysine versus placebo study were reanalyzed in order to compare the results of different scoring methods and to provide an auranofin versus placebo comparison. Two readers found the rate of erosion during oral gold therapy to be less than that predicted by the analytical model. Interobserver differences in scoring were demonstrated. A breakdown of patient scores by duration of disease showed the greatest difference between scores observed during treatment with those predicted by the model in patients with early disease.

Adult↗
PubMed1982

Defective monocyte cytotoxicity in rheumatoid arthritis: a correlation with disease activity and reversal by levamisole.

The cytotoxic activities of human blood mononuclear cells against certain established cell lines were evaluated prospectively in 17 patients with rheumatoid arthritis before and after treatment with low (150 mg per week) and moderate doses (300 mg per week) of levamisole. Spontaneous or "natural" killer activity (NK) and antibody-dependent cellular cytotoxicity (ADCC) of plastic adherent cells ("monocytes") and lymphocytes were studied. We report a selective cytotoxic defect in monocyte NK and a correlation of this defect with severely active disease. The patients with the most severe defect responded to low-dose levamisole, but others with normal values did nor respond as well to treatment. This cytotoxic defect may be an important pathogenetic factor in rheumatoid arthritis and this new assay may be helpful in selecting candidates who are most likely to respond to levamisole.

Adult↗
PubMed1981

Influence of maternal dietary protein and fat levels on fetal growth in mice.

The influence of maternal dietary fat and protein levels during gestation on fetal growth was determined in LAF1/J mice. Dams were fed diets containing various levels of casein (ranging from 6 to 20%) and fat (either 5 or 15%). On the 18th day of gestation, all animals were sacrificed. Products of conception were examined, and maternal liver and fetal body compositional analysis was performed. It was found that low protein diets did not depress caloric intake, indicating that observed effects are due to differences in respective nutrient intakes rather than altered caloric intakes. Both the dietary protein and fat levels significantly influenced the fetal cellular growth (cell number rather than cell size) of LAF1/J mice. In addition, dietary fat influenced protein adequacy for satisfactory fetal cellular growth of these mice, probably by altering protein utilization. Optimal fetal cellular growth was obtained with the diet containing 20% casein and 15% fat as indicated by increased fetal protein, DNA, and RNA contents. Normal maternal liver lipid content in animals fed the 20% protein and 15% fat diet also indicates that this diet is optimal for gestational performance of LAF1/J mice.

Animals↗