Biomedical subjects

M C Olson

Publications and source records attributed to M C Olson.

At least 19 recordsLinked to original sources

PubMed2001

An invasive cleavage assay for direct quantitation of specific RNAs.

RNA quantitation is becoming increasingly important in basic, pharmaceutical, and clinical research. For example, quantitation of viral RNAs can predict disease progression and therapeutic efficacy. Likewise, gene expression analysis of diseased versus normal, or untreated versus treated, tissue can identify relevant biological responses or assess the effects of pharmacological agents. As the focus of the Human Genome Project moves toward gene expression analysis, the field will require a flexible RNA analysis technology that can quantitatively monitor multiple forms of alternatively transcribed and/or processed RNAs (refs 3,4). We have applied the principles of invasive cleavage and engineered an improved 5'-nuclease to develop an isothermal, fluorescence resonance energy transfer (FRET)-based signal amplification method for detecting RNA in both total RNA and cell lysate samples. This detection format, termed the RNA invasive cleavage assay, obviates the need for target amplification or additional enzymatic signal enhancement. In this report, we describe the assay and present data demonstrating its capabilities for sensitive (<100 copies per reaction), specific (discrimination of 95% homologous sequences, 1 in > or =20,000), and quantitative (1.2-fold changes in RNA levels) detection of unamplified RNA in both single- and biplex-reaction formats.

Base Sequence↗

PubMed1999

Hepatic enhancement analysis in children using smart prep monitoring for 2 : 1 pitch helical scanning.

PURPOSE: To analyze hepatic enhancement by using Smart Prep protocols appropriate for children of different weight groups and 2:1 pitch helical CT imaging as the investigative tools. PATIENTS AND METHODS: A group of 55 children ranging in weight between 20 and 180 lbs underwent 67 contrast-enhanced abdominal helical CT examinations using Smart Prep (GE Medical Systems, Milwaukee, Wisc.). Of these studies, 21 (31 %) were excluded because of failure to follow the prescribed Smart Prep protocols. Smart Prep protocols were established for nine different weight groups. Scan delay, aorta and liver time to peak, and liver enhancement over baseline were recorded. RESULTS: Optimal abdominal CT studies with adequate contrast enhancement of hepatic and portal veins were obtained in 46 patients. There was no significant difference in the time between peak aortic and the liver enhancement among different weight groups (mean time 12.0 +/- 7.1 s for all children). However, the mean hepatic enhancement over baseline in children weighing < 30 lbs was below 50 Hounsfield units (HU) compared to the rest of the children who had mean hepatic enhancement of > 50 HU. CONCLUSION: Two-thirds of the Smart Prep protocols were successfully implemented, and all of these resulted in good contrast enhancement of hepatic and portal veins. Optimal mean liver enhancement (> 50 HU) was seen in children >/= 30 lbs. Children < 30 lbs had mean liver enhancement of 33 HU +/- 7.2 above the baseline likely caused by contrast dose.

Adolescent↗

PubMed1999

"The heart still beat, but the brain doesn't answer". Perception and experience of old-age dementia in the Milwaukee Hmong community.

The purpose of this exploratory and descriptive study was to examine old-age dementia in the Hmong community of Milwaukee, Wisconsin. Formal and informal Hmong leaders were interviewed to determine the prevalence of dementia in the Hmong community and how it is perceived and experienced. Interviews revealed few cases of dementia among the Hmong. Dementia was perceived as a natural part of the life cycle, rather than as a devastating disease that robs individuals of their autonomy. Treatment is not sought for dementia. Some of the common manifestations of dementia, such as wandering and combativeness, were rare or non-existent in the Hmong community. Individuals with dementia are cared for in their sons' homes. Nursing home placement in advanced dementia was only acceptable if sanctioned by the entire extended family. Further research on the Hmong perception of and experience with dementia needs to be conducted in other Hmong communities to validate the generalizability of these results.

Aged↗

PubMed1998

Transthoracic fine-needle aspiration cytology of inflammatory pseudotumor, fibrohistiocytic type: a case report with immunohistochemical studies.

Inflammatory pseudotumor, fibrohistiocytic type, also called benign fibrous histiocytoma, is a rare reactive entity usually found incidentally on routine chest roentgenography. We present a case of inflammatory pseudotumor, fibrohistiocytic type, initially diagnosed by fine-needle aspiration (FNA) cytology in a 39-yr-old woman with a history of breast carcinoma. Cytomorphologic characteristics were confirmed by a cell block examination and immunohistochemical findings. The differential diagnoses of the fine-needle aspiration cytology of this type of inflammatory pseudotumor are discussed.

Adult↗

PubMed1998

Normal myeloid development requires both the glutamine-rich transactivation domain and the PEST region of transcription factor PU.1 but not the potent acidic transactivation domain.

Gene targeting of transcription factor PU.1 results in an early block to fetal hematopoiesis, with no detectable lymphoid or myeloid cells produced in mouse embryos. Furthermore, PU.1(-/-) embryonic stem (ES) cells fail to differentiate into Mac-1(+) and F4/80(+) macrophages in vitro. We have previously shown that a PU.1 transgene under the control of its own promoter restores the ability of PU. 1(-/-) ES cells to differentiate into macrophages. In this study, we take advantage of our PU.1(-/-) ES cell rescue system to genetically test which previously identified PU.1 functional domains are necessary for the development of mature macrophages. PU.1 functional domains include multiple N-terminal acidic and glutamine-rich transactivation domains, a PEST domain, several serine phosphorylation sites, and a C-terminal Ets DNA binding domain, all delineated and characterized by using standard biochemical and transactivational assays. By using the production of mature macrophages as a functional readout in our assay system, we have established that the glutamine-rich transactivation domain, a portion of the PEST domain, and the DNA binding domain are required for myelopoiesis. Deletion of three acidic domains, which exhibit potent transactivation potential in vitro, had no effect on the ability of PU.1 to promote macrophage development. Furthermore, mutagenesis of four independent sites of serine phosphorylation also had no effect on myelopoiesis. Collectively, our results indicate that PU.1 interacts with important regulatory proteins during macrophage development via the glutamine-rich and PEST domains. The PU.1(-/-) ES cell rescue system represents a powerful, in vitro strategy to functionally map domains of PU.1 essential for normal hematopoiesis and the generation of mature macrophages.

3T3 Cells↗

PubMed1998

Prostate carcinoma: transrectal US after cryosurgical ablation.

PURPOSE: To characterize the transrectal ultrasound (US) morphology of the prostate after cryosurgical ablation and correlate these findings with the detection of residual tumor at transrectal US-directed biopsy. MATERIALS AND METHODS: Findings from 24 transrectal US examinations in 15 patients (age range, 63-75 years) who had undergone cryosurgical ablation of the prostate were reviewed. Prospective identification of focal lesions with transrectal US and retrospective review of US prostate morphology were correlated with clinical data and transrectal US-directed biopsy results. RESULTS: Identification of a focal lesion with transrectal US yielded a sensitivity of 13%, specificity of 69%, positive predictive value of 17%, and negative predictive value of 61% for the detection of residual carcinoma. US prostate morphology was variable and distorted in the majority of cases. CONCLUSION: Identification of focal lesions with transrectal US is not a reliable criterion for the detection of residual tumor in the prostate after cryosurgical ablation. Systematic biopsy should not be deferred owing to lack of transrectal US identification of focal abnormalities in patients with appropriate clinical indications.

Aged↗

PubMed1998

Assessing the resectability of pancreatic carcinoma: the value of reinterpreting abdominal CT performed at other institutions.

OBJECTIVE: The purpose of this study was to determine the value of reinterpreting abdominal CT performed at other institutions when assessing the resectability of pancreatic carcinoma. MATERIALS AND METHODS: Fifty-three patients (30 men, 23 women; mean age, 62 years) referred to our tertiary care institution with newly diagnosed pancreatic carcinoma had formally reinterpreted abdominal CT scans and available initial reports. CT was performed at community hospitals (n = 47), university hospitals (n = 4), an outpatient clinic (n = 1), and an imaging center (n = 1); reinterpretation was performed by university radiologists with subspecialty expertise in abdominal imaging. On the basis of the initial and reinterpretation reports, the patients were categorized as having resectable or nonresectable disease. Medicare reimbursement rates were assessed. RESULTS: The initial and reinterpretation reports agreed in 36 (68%) of the 53 patients, with the disease of 16 patients considered resectable and 20 unresectable by both reports. In 17 patients (32%), we found discrepancies between the initial and the reinterpretation reports. All discrepancies involved the initial report indicating resectability and the reinterpretation report consistent with nonresectable disease. Discrepancies were resolved by findings at surgery (n = 9), percutaneous biopsy (n = 3), dedicated pancreatic CT (n = 3), dedicated liver CT (n = 1), and follow-up abdominal CT (n = 1); the reinterpretation reports were correct in 16 (94%) of 17 patients. Reimbursement for outside CT reinterpretation, repeated abdominal CT, and an exploratory laparotomy were estimated at $46.45, $414.47, and $16,996.44, respectively. CONCLUSION: Reinterpretation of outside abdominal CT was valuable for determining pancreatic carcinoma resectability and inexpensive when compared with repeating the CT examination or performing an exploratory laparotomy.

Adenocarcinoma↗

PubMed1997

PU.1 functions in a cell-autonomous manner to control the differentiation of multipotential lymphoid-myeloid progenitors.

Transcription factor PU.1 is required for the development of lymphoid and myeloid progenitors during fetal hematopoiesis. By generating chimeric animals using PU.1-/- ES cells or PU.1(-/-) hematopoietic progenitors, we demonstrate that PU.1 functions in an exclusively cell-autonomous manner to regulate the development of the lymphoid-myeloid system. Multipotential lymphoid-myeloid progenitors (AA4.1+, Lin-) are significantly reduced in PU.1(-/-) embryos and fail to differentiate into B lymphoid or myeloid cells in vitro. These results suggest that the lymphoid and myeloid lineages develop in the fetal liver from a common hematopoietic progenitor not shared with erythrocytes and megakaryocytes. Finally, the Ikaros gene is expressed in PU.1 mutant embryos, suggesting that PU.1 and Ikaros are independently required for specification of embryonic lymphoid cell fates.

Animals↗

PubMed1996

Transcription factor GATA-3 is required for development of the T-cell lineage.

THE zinc-finger transcription factor GATA-3 is expressed in haematopoietic cells and in the developing kidney and nervous system. Within the haematopoietic lineages, expression of GATA-3 is restricted to thymocytes and T cells. Functionally important GATA-3 binding sites have been identified in multiple T-cell-specific genes. Mice containing homozygous null mutations of the GATA-3 gene die on embryonic day 12, precluding a detailed assessment of the role of GATA-3 in haematopoietic development. Here we have used murine embryonic stem (ES) cells containing homozygous mutations in the GATA-3 gene (GATA-3(-/-)) in conjunction with the RAG-2(-/-) (ref. 10) and C57BL/6 complementation systems to study the role of GATA-3 in mammalian haematopoiesis. Our results show that GATA-3(-/-) ES cells can contribute to the development of the mature erythroid, myelomonocytic and B-cell lineages, but fail to give rise to thymocytes or mature peripheral T cells. The differentiation of GATA-3(-/-) T cells is blocked at or before the earliest double-negative (CD4-/CD8-) stage of thymocyte development, such that the GATA-3(-/-) ES cells are unable to contribute measurably to the double-negative thymocyte population. These findings suggest that GATA-3 is an essential and specific regulator of early thymocyte development.

Animals↗

PubMed1996

Evaluation of image quality using 1 : 1 pitch and 1.5 : 1 pitch helical CT in children: a comparative study.

OBJECTIVE: The objective of this study was to compare the quality of 1 : 1 and 1.5 : 1 pitch helical contrast-enhanced thoracic and abdominal CT images in children who cannot cooperate for breath holding. MATERIALS AND METHODS: This is a retrospective study of 33 contrast-enhanced CT examinations in 11 children of 0-4 years of age. All children had an initial CT study using 1 : 1 pitch helical scanning followed over the next 6-36 months by one to four CT examinations with 1.5 : 1 pitch. Radiation dose with the two techniques was measured with a pencil ionization chamber. RESULTS: The two techniques provided comparable overall image quality. There was 33 % less radiation dose with 1.5 : 1 pitch helical scanning. CONCLUSION: The 1.5 : 1 pitch helical CT provides comparable quality images and a smaller radiation dose than 1 : 1 pitch in examining children aged 0-4 years.

Child↗

PubMed1996

Assessment of a technology that permits individualized scan delays on helical hepatic CT: a technique to improve efficiency in use of contrast material.

OBJECTIVE: We performed this study to assess the usefulness of a computer automated scan technology (CAST) for individualizing scan delay during helical CT to improve the efficiency of hepatic enhancement. SUBJECTS AND METHODS: We prospectively evaluated 183 patients who were randomized into five groups. Control patients received 100 or 150 ml of contrast material (320 mg I/ml) with a 60-sec delay between contrast injection at 3 ml/sec and scanning. CAST patients received 100, 125, or 150 ml. In our latter groups we used an hepatic enhancement threshold of 50 H over baseline to determine the optimum delay between contrast injection and scanning. For the intergroup comparisons, we measured the liver on baseline and enhanced helical CT scans at the upper, mid, and lower levels of the liver. RESULTS: The mean enhancement in patients who received 150 ml of contrast material was 70.7 +/- 19.4 H for the control group and 81.0 +/- 17.5 H for the CAST group (p < .05). Hepatic enhancement above 50 H was achieved in 84% of the control subjects compared with 100% of CAST subjects; more than 60 H hepatic enhancement was achieved in 73% of control subjects and in 89% of CAST subjects. The use of CAST software with 125-ml contrast doses provided enhancement equivalent to that of control subjects who received 150 ml of contrast material (mean enhancement in CAST subjects, 70.3 +/- 15.4 H). Enhancement above 50 H was reached in 98% of CAST and 84% of control patients. With 100 ml of contrast material, 24% of patients failed to initiate CAST, resulting in enhancement similar to control patients (CAST, 54.2 +/- 11.4 H; controls, 56.9 +/- 15.2 H). CONCLUSION: Using a contrast dose of 150 ml, CAST provided significantly increased hepatic enhancement than that achieved in control subjects with less variability. For equivalent hepatic enhancement, contrast doses could be decreased by 25 ml using CAST technology because it provides individualized scan delays.

Adult↗

PubMed1996

Helical computed tomography at 1.5:1 pitch reconstructed at 15-mm and 7-mm intervals for examination of patients with suspected metastatic disease.

OBJECTIVE: To document the need for overlapped reconstruction when using helical computed tomography (CT) software that reconstructs 10-mm-collimation, 1.5:1-pitch images at 15-mm intervals in follow-up examination of patients with suspected metastatic disease. PATIENTS AND METHODS: Forty consecutive patients with known or suspected metastatic disease were examined with helical CT at 10-mm collimation and 1.5:1 pitch. The studies were examinations of the chest, abdomen and pelvis; the chest and abdomen; or the abdomen and pelvis. Two image sets, one prospectively reconstructed at 15-mm intervals and the other retrospectively reconstructed at 7-mm intervals, were independently reviewed by three radiologists, and the number, size and location of lesions were documented. Differences in interpretation were resolved by consensus. The lesions detected on the two sets of images were classified according to lesion size and location, and the results were analysed by multivariate analysis of variance with repeated measures. RESULTS: Images reconstructed at 7-mm intervals revealed a total of 436 lesions, 127 (41%) more than were revealed by images reconstructed at 15-mm intervals. The number of lesions less than 1 cm in diameter that were visible in the two sets of images was significantly different (p = 0.018). However, there was no significant difference between the two sets of images in terms of lesion location. CONCLUSION: Metastatic lesions may be missed by helical CT at 1.5:1 pitch if overlapped reconstruction is not performed.

Abdominal Neoplasms↗

PubMed1995

The variation of inguinal lymph node depth in adult women and its importance in planning elective irradiation for vulvar cancer.

BACKGROUND: The Gynecologic Oncology Group (GOG) protocol #88 reported an 18.5% failure in inguinal lymph nodes of patients with vulvar cancer whose groins were treated with radiation alone. This high failure rate may be due to the study design. METHODS: In this study, the depths of inguinal lymph nodes were evaluated with computed tomography (CT) scans in 100 adult women without inguinal adenopathy or prior inguinal surgery. The dose that would have been delivered to the inguinal lymph nodes of these patients was determined using isodose curves constructed according to the guidelines in GOG protocol #88. RESULTS: Only 18% of women had all inguinal lymph nodes measured at a depth of 3 cm or less. CONCLUSIONS: More than one-half of all women in this study would have received less than 60% of the prescribed radiation dose because their inguinal lymph nodes were deeper than 5 cm, if the depth of their inguinal lymph nodes had not been measured before therapy.

Adult↗

PubMed1995

PU. 1 is not essential for early myeloid gene expression but is required for terminal myeloid differentiation.

We have previously shown using gene targeting that PU.1 is essential for the development of lymphoid and myeloid lineages during fetal liver hematopoiesis. We now show that PU.1 is required for the maturation of yolk sac-derived myeloid progenitors and for the differentiation of ES cells into macrophages. The role of PU.1 in regulating target genes, thought to be critical in the development of monocytes and granulocytes, has been analyzed. Early genes such as GM-CSFR, G-CSFR, and myeloperoxidase are expressed in PU.1-/- embryos and differentiated PU.1-/- ES cells. However, the expression of genes associated with terminal myeloid differentiation (CD11b, CD64, and M-CSFR) is eliminated in differentiated PU.1-/- ES cells. Development of macrophages is restored with the introduction of a PU.1 cDNA regulated by its own promoter. The PU.1-/- ES cells represent an important model for analyzing myeloid cell development.

Animals↗

PubMed1995

Sonography of the umbilical cord.

Knowledge of the development, normal sonographic appearance, and potential abnormalities of the umbilical cord is important in fetal assessment. The umbilical cord can be visualized throughout most of gestation and is detectable sonographically soon after visualization of the fetal pole. The normal umbilical cord is 50-60 cm long and may coil as many as 40 times, usually to the left. Abnormalities in umbilical cord size, degree of coiling, attachment, and position can have important implications for the outcome of the pregnancy. Structural abnormalities of the umbilical cord such as single umbilical artery, knots, cysts, and tumors may be associated with fetal distress or malformations. Color Doppler ultrasound (US) is useful in the identification and evaluation of structural abnormalities of the cord. By allowing measurement of blood flow velocity in the umbilical artery, duplex Doppler US may provide additional information in the evaluation of intrauterine growth retardation and twin-twin transfusion syndrome.

Blood Flow Velocity↗

PubMed1995

Urologic applications of multiplanar and three-dimensional computed tomography.

The introduction of helical computed tomography (CT) has resulted in improved quality of multiplanar reformations and three-dimensional reconstructions in the chest and abdomen and has made CT angiography a clinical reality. These imaging techniques are useful for evaluating the urinary tract, adding a new dimension to its display, resulting in improved diagnosis of renal and perirenal disease. This article reviews the indications and techniques utilized for multiplanar and three-dimensional CT for urology. The advantages and limitations are discussed, and normal and pathologic findings in the urinary tract illustrated.

Angiography↗

PubMed1994

The persistent computed tomography nephrogram: its significance in the diagnosis of contrast-associated nephrotoxicity.

A study was undertaken to find out if there is a quantitative relationship between the development of contrast-associated nephrotoxicity (CAN) and the mean renal cortical attenuation (RCA) as seen on computed tomography (CT) examination of the kidneys 24 hours after injection of contrast medium. 96 patients undergoing aortography were selected, who were considered "high risk" either because of the presence of a baseline serum creatinine (Cr) of 123.76 mumol l-1 (1.4 mg dl-1) or higher, or who were 73 or older with or without elevated creatinine levels. A CT study of the kidneys at approximately 24 h was correlated with baseline serum creatinine as well as 24 h Cr (48-72 h Cr when available). Medical history and medications were recorded. Eight of 96 patients had RCA of 108-236 HU at 24 h CT and all developed significant CAN of varying degree; 3/96 had RCA ranging from 48 to 67 HU and had transient CAN; two other patients with RCA of 67-90 HU developed CAN; and there was increased incidence of CAN in patients: (a) with pre-existing renal insufficiency; (b) with diabetes with renal insufficiency; (c) on diuretics; (d) who were older; and (e) had a unilateral atrophic kidney. It was concluded that a 24 h CT study evaluating the RCA had better predictive value for the development of CAN than a 24 h creatinine level.

Age Factors↗

PubMed1994

CT of the chest and abdomen in patients on mechanical pulmonary ventilators: quality of images made at 0.6 vs 1.0 sec.

OBJECTIVE: Chest and abdominal CT scans using 1.0-sec scan times are often limited by motion in patients who are unable to hold their breath. With our scanner we can obtain images in 0.6 sec (partial scan) that use data from 225 degrees instead of the 360 degrees used for 1.0-sec scans. The purpose of this study was to assess whether the quality of images of the chest and abdomen in patients on mechanical pulmonary ventilators who could not breath-hold could be improved if images were taken using a scan time of 0.6 sec rather than 1.0 sec. MATERIALS AND METHODS: Thirty patients who were being treated with mechanical pulmonary ventilation with indications for chest or abdominal CT or both were scanned with a scan time of 1.0 sec. At the end of the examination, additional 0.6-sec images were taken at three or four levels. Images obtained with these two scan times were filmed at similar levels and windows, and anatomically matched levels were compared. The images were masked and independently evaluated by three radiologists for motion, noise, artifact, and overall image quality. Each parameter was rated using a scale of 1 to 4. Using Kendall's tau correlation, there was no significant difference between the radiologists in the grading of individual parameters or of overall image quality. Therefore, the average of the scores of the three radiologists was used. Statistical analysis was done using repeated measures multivariate analysis of variance. RESULTS: Images obtained in 0.6 sec had significantly less motion (p < .001) but more noise (p < .001) than those obtained in 1.0 sec. We found no statistically significant difference in artifacts between the two scan times. Overall image quality was judged to be significantly better on scans obtained in 0.6 sec than on scans obtained at 1.0 sec (p < .001), in spite of the greater noise on 0.6-sec images. The higher quality of 0.6-sec images was most noticeable for lung window settings. CONCLUSION: Our results indicate that scans taken in 0.6 sec (partial scans) provide better quality images than those obtained in 1.0 sec in patients being treated with mechanical pulmonary ventilation who cannot breath-hold. This technique may be useful not only in this population but in all patients who are unable to cooperate with breath-holding instructions.

Contrast Media↗