Unenhanced helical CT using increased pitch for suspected renal colic: an effective technique for radiation dose reduction?

PURPOSE

To determine the accuracy and utility of unenhanced helical CT for suspected renal colic, using a pitch of either 2.5 or 3.0.

METHODS

59 consecutive patients underwent unenhanced helical CT. 5 mm contiguous images were obtained at a kVP of 120 and an mA of 260. Thirty-four patients were imaged at a pitch of 2.5, and 25 patients were imaged at a pitch of 3.0. Two radiologists, an attending (reader 1), and a second-year resident (reader 2), independently and retrospectively reviewed the CT images, blinded to the clinical outcome. The presence or absence of a ureteral stone was recorded and image quality was graded. A third radiologist determined accuracy for each reader. Average entrance exposure was estimated using a CT phantom at a variety of pitches.

RESULTS

Overall sensitivity, specificity, and accuracy for reader 1 were 91, 96, and 93%. For reader 2, they were 86, 93, and 90%. There was no significant difference in accuracy using a pitch of 3.0 compared with 2.5 for either reader. Readers 1 and 2 rated image quality at 2.5 pitch as excellent for 88 and 76% of scans, respectively; at 3.0 pitch the scans were rated by both readers as excellent for 40% and acceptable for 60%. Average entrance exposures were estimated at 461, 553. and 913 mR at pitches of 3.0, 2.5, and 1.5.

CONCLUSION

Increasing the pitch on unenhanced helical CT for suspected renal colic to 2.5 or 3.0 appears to be an effective method of reducing radiation dose. Although accuracy of the technique did not significantly change using a pitch of 3.0 in one group of patients, compared with a pitch of 2.5 in another group of patients, image quality did decrease.

Alternative or additional diagnoses on unenhanced helical computed tomography for suspected renal colic: experience with 1000 consecutive examinations

OBJECTIVES

To determine the incidence and spectrum of significant alternative or additional diagnoses established or suggested on unenhanced helical computed tomography (CT) in a large series of patients with suspected renal colic.

METHODS

One thousand consecutive unenhanced helical CT examinations were performed for suspected renal colic. All official CT reports were retrospectively reviewed, which was followed by review of all available relevant follow-up radiology reports. A selected image and chart review was also performed.

RESULTS

Ureteral calculi were identified on 557 examinations, findings consistent with a recently passed stone were discovered on 67 examinations, and 275 CT examinations were unremarkable. An alternative or additional diagnosis was established or suggested on 101 examinations, including in 26 patients with concurrent ureteral calculi. There were 62 genitourinary and 39 nongenitourinary tract diagnoses. Eighty-seven of the diagnoses could be confirmed on retrospective image review combined with patient follow-up. There were two false-positive diagnoses for significant, alternative pathologic findings.

CONCLUSIONS

A wide spectrum of significant, alternative, and additional genitourinary and nongenitourinary diagnoses can be reliably established or suggested on unenhanced helical CT performed for suspected renal colic. These abnormalities were identified in 10% of cases in this series of 1000 consecutive CT examinations.

Predicting sequence-dependent melting stability of short duplex DNA oligomers

Many important applications of DNA sequence-dependent hybridization reactions have recently emerged. This has sparked a renewed interest in analytical calculations of sequence-dependent melting stability of duplex DNA. In particular, for many applications it is often desirable to accurately predict the transition temperature, or tm of short duplex DNA oligomers (approximately 20 base pairs or less) from their sequence and concentration. The thermodynamic analytical method underlying these predictive calculations is based on the nearest-neighbor model. At least 11 sets of nearest-neighbor sequence-dependent thermodynamic parameters for DNA have been published. These sets are compared. Use of the nearest-neighbor sets in predicting tm from the DNA sequence is demonstrated, and the ability of the nearest-neighbor parameters to provide accurate predictions of experimental tm's of short duplex DNA oligomers is assessed.

Suspected acute appendicitis: nonenhanced helical CT in 300 consecutive patients

PURPOSE

To determine the accuracy of helical computed tomography (CT) without the oral, intravenous, or rectal administration of contrast material in confirming suspected acute appendicitis.

MATERIALS AND METHODS

Three hundred consecutive patients referred from the departments of surgery and emergency medicine were examined for suspected acute appendicitis by using thin-section nonenhanced helical CT. All transverse CT scans were obtained in a single breath hold from the upper abdomen (T12 vertebra) to the pubic symphysis with 5-mm collimation and a pitch of 1.6. All scans were obtained without oral, intravenous, or rectal contrast material. Criteria for diagnosis of acute appendicitis included an enlarged appendix (> 6 mm) and periappendiceal inflammation. CT diagnoses were recorded prospectively. Final diagnoses were established with the results of surgical or clinical follow-up or both.

RESULTS

There were 110 true-positive diagnoses, 181 true-negative diagnoses (63 of which were an alternative diagnosis correctly established prospectively), five false-negative diagnoses, and four false-positive diagnoses, which yielded a sensitivity of 96%, a specificity of 99%, and an accuracy of 97%.

CONCLUSION

Nonenhanced helical CT is a highly accurate technique for diagnosing or excluding acute appendicitis. Developing experience with the technique and understanding the subtleties of interpretation can further improve diagnostic accuracy.

Melting studies of short DNA hairpins: influence of loop sequence and adjoining base pair identity on hairpin thermodynamic stability

Spectroscopic and calorimetric melting studies of 28 DNA hairpins were performed. These hairpins form by intramolecular folding of 16 base self-complementary DNA oligomer sequences. Sequence design dictated that the hairpin structures have a six base pair duplex linked by a four base loop and that the first five base pairs in the stem are the same in every molecule. Only loop sequence and identity of the duplex base pair closing the loop vary for the set of hairpins. For these DNA samples, melting studies were carried out to investigate effects of the variables on hairpin stability. Stability of the 28 oligomers was ascertained from their temperature-induced melting transitions in buffered 115 mM Na(+) solvent, monitored by ultraviolet absorbance and differential scanning calorimetry (DSC). Experiments revealed the melting temperatures of these molecules range from 32.4 to 60.5 degrees C and are concentration independent over strand concentrations of 0.5 to 260 microM; thus, as expected for hairpins, the melting transitions are apparently unimolecular. Model independent thermodynamic transition parameters, DeltaH(cal), DeltaS(cal), and DeltaG(cal), were determined from DSC measurements. Model dependent transition parameters, DeltaH(vH), DeltaS(vH), and DeltaG(vH) were estimated from a van't Hoff (two-state) analysis of optical melting transitions. Results of these studies reveal a significant sequence dependence to DNA hairpin stability. Thermodynamic parameters evaluated by either procedure reveal the transition enthalpy, DeltaH(cal) (DeltaH(vH)) can differ by as much as 20 kcal/mol depending on sequence. Similarly, values of the transition entropy DeltaS(cal) (DeltaS(vH)) can differ by as much as 60 cal/Kmol (eu) for different molecules. Differences in free energies DeltaG(cal) (DeltaG(vH)) are as large as 4 kcal/mol for hairpins with different sequences. Comparisons between the model independent calorimetric values and the thermodynamic parameters evaluated assuming a two-state model reveal that 10 of the 28 hairpins display non-two-state melting behavior. The database of sequence-dependent melting free energies obtained for the hairpins was employed to extract a set of n-n (nearest-neighbor) sequence dependent loop parameters that were able to reproduce the input data within error (with only two exceptions). Surprisingly, this suggests that the thermodynamic stability of the DNA hairpins can in large part be reasonably represented in terms of sums of appropriate nearest-neighbor loop sequence parameters.

Thermodynamic, spectroscopic, and equilibrium binding studies of DNA sequence context effects in six 22-base pair deoxyoligonucleotides

Effects of different end sequences on stability, circular dichroism spectra (CD), and enzyme binding properties were investigated for six 22-base pair, non-self-complementary duplex DNA oligomers. The center sequences of these deoxyoligonucleotides have 8-14 base pairs in common and are flanked on both sides by sequences differing in context and A-T content. Temperature-induced melting transitions monitored by differential scanning calorimetry (DSC) and ultraviolet absorbance were measured for the six duplexes in buffered 115 mM Na(+) solutions. Values of the melting transition enthalpy, DeltaH(cal), and entropy, DeltaS(cal), were obtained directly from DSC experiments. Melting transition parameters, DeltaH(vH) and DeltaS(vH), were also estimated from van't Hoff analysis of optical melting curves collected as a function of DNA concentration, assuming a two-state melting transition. Melting free energies (20 degrees C) of the six DNAs evaluated from DSC experiments ranged from -18.7 to -32.7 kcal/mol. van't Hoff estimates of the free energies ranged from -18.5 to -48.0 kcal/mol. With either method, the trends in free energy as a function of sequence were identical. Equilibrium binding by BamHI restriction endonuclease to the 22-base pair DNAs was also investigated. The central eight base pairs of all six molecules, 5'-A-GGATCC-A-3', contained a BamHI recognition sequence bounded by A-T base pairs. Magnesium free binding assays were performed by titering BamHI against a constant concentration of each of the deoxyoligonucleotide substrates and analyzing reaction products by gel retardation. Binding isotherms of the total amount of bound DNA versus protein concentration were constructed which provided semiquantitative estimates of the equilibrium dissociation constants for dissociation of BamHI from the six DNA oligomers. Dissociation constants ranged from 0.5 x 10(-)(9) to 12.0 x 10(-)(9) M with corresponding binding free energies of -12.5 to -10.6 (+/-0. 1) kcal/mol. An inverse relationship is found when binding and stability are compared.

Parathyroid localization with high-resolution ultrasound and technetium Tc 99m sestamibi

HYPOTHESIS

High-resolution ultrasound and technetium Tc 99m sestamibi scanning can be used for preoperative localization of abnormal parathyroid glands in patients with hyperparathyroidism.

DESIGN

Ultrasound and sestamibi scanning were performed in patients undergoing neck exploration for hyperparathyroidism. If the 2 scans agreed in identifying a single adenoma, and surgery confirmed the location of a single adenoma and an ipsilateral normal gland, a unilateral exploration was performed.

SETTING

University tertiary care center.

PATIENTS

Sixty-one consecutive patients undergoing surgery for hyperparathyroidism from September 1, 1994, through September 30, 1997.

INTERVENTIONS

High-resolution ultrasound was performed in 59 patients and sestamibi scanning in 58 patients; all patients underwent neck exploration by a single surgeon.

MAIN OUTCOME MEASURES

The results of preoperative ultrasound and sestamibi scanning were compared with operative and histological findings.

RESULTS

All patients were cured of hypercalcemia. Specificity of ultrasound and sestamibi scanning was 98% and 99%, respectively; however, their sensitivity was only 57% and 54%, respectively. Both imaging modalities had lower sensitivities in the setting of multigland disease. If both imaging studies were considered as a single test, sensitivity for imaging in patients with primary hyperparathyroidism reached 78%. Our localization protocol allowed a unilateral approach in 43% of patients (23 of 53).

CONCLUSIONS

These results confirm the value of preoperative localization in patients with hyperparathyroidism. A unilateral approach can be used with a high degree of success in cases when ultrasound and sestamibi scanning agree in the identification of a single adenoma confirmed by surgical exploration with the identification of a normal ipsilateral gland.

The value of strength training for older adults

Health in older adults can best be measured in terms of functional status. Skeletal muscle strength has been reported to be a determinant of functional status in older individuals. Two major contributors to the decline in muscle function as a person ages are disuse and physical inactivity. Declining muscle function through a loss of muscular strength may decrease functional independence and mobility and increase the risk for falls and injuries, physical frailty, and disability. Older individuals lacking an appropriate amount of muscular strength may not be able to perform various activities of daily living, which are important indicators of independence.

Unenhanced CT of abdominal and pelvic hemorrhage

CT performed without oral or intravenous contrast is the initial imaging study of choice in many situations for the detection of hemorrhage anywhere in the abdomen and pelvis. The presence or absence of hemorrhage can be determined rapidly, and the amount and precise location of hemorrhage can also be evaluated. This article reviews the appearances and the common and unusual etiologies of abdominal and pelvic hemorrhage on unenhanced CT. The role of intravenous contrast-enhanced CT in patients with known or suspected abdominal and pelvic hemorrhage is also examined.

Appendicitis and its mimickers

Unenhanced helical CT is an accurate technique for the evaluation of patients with suspected acute appendicitis. This non-operator-dependent examination can be performed without the risk of intravenous contrast material or the delay associated with the use of oral and rectal contrast material. This article reviews the unenhanced helical CT findings of acute appendicitis and those entities that commonly mimic acute appendicitis clinically.

Use of color and power Doppler sonography to identify feeding arteries associated with parathyroid adenomas

OBJECTIVE

The objective of our study was to determine the value of using color and power Doppler sonography to reveal extrathyroidal feeding arteries in the detection of abnormal parathyroid glands.

SUBJECTS AND METHODS

Forty-four patients with primary hyperparathyroidism were imaged prospectively with high-resolution gray-scale, color flow, and power Doppler sonography. The presence of extrathyroidal arteries supplying the adenomas was noted. All patients underwent subsequent neck exploration. The locations of the abnormal glands were recorded.

RESULTS

At surgery, 51 abnormal parathyroid glands were removed in the 44 patients. Sonography correctly revealed an adenoma in 40 of the 44 patients. Likewise, sonography revealed 42 of the 51 adenomas. Nine false-negative and two false-positive interpretations of the sonograms were made. Thus, overall sensitivity was 83%, specificity was 98%, and accuracy was 94%. Three of the false-negative interpretations were ectopic glands within the superior mediastinum. Excluding these three glands from analysis, the sensitivity for detection of adenomas within the neck was 88%, specificity was 98%, and accuracy was 95%. An extrathyroidal artery leading to a parathyroid adenoma was seen in 35 of the 42 adenomas revealed by sonography. The presence of an extrathyroidal artery leading to an adenoma was found to aid in the detection of an otherwise inconspicuous parathyroid gland in five patients, which improved sensitivity from 73% to 83%.

CONCLUSION

Prominent vessels supplying parathyroid adenomas are frequently revealed by color flow and power Doppler sonography. These vessels can serve as "road maps" to abnormal parathyroid glands.

Lipomas of the pancreas

OBJECTIVE

The purpose of this study was to describe the CT findings of pancreatic lipomas in four patients.

CONCLUSION

In all four cases, the lipoma was revealed incidentally on CT scans obtained for other reasons. CT scans were diagnostic, showing well-circumscribed masses within the pancreas composed almost entirely of fat, with a few scattered vessels or septa or both, which ranged in size from 1.4 x 2.0 cm to 4.5 x 5.3 cm in the axial plane. Pancreatic lipomas are rare, usually incidental tumors and, as with lipomas found elsewhere in the body, conservative management is often indicated.

Primary malignant pulmonary hemangiopericytoma

A primary malignant pulmonary hemangiopericytoma was diagnosed in a 45-year-old woman who complained of 10 months of cough and exertional dyspnea. One year after resection of the mass, a metastatic lesion was removed from the contralateral lung. The literature on this unusual pulmonary lesion is reviewed.

Spontaneous intramural small bowel haemorrhage: importance of non-contrast CT

The purpose of this study was to evaluate the abdominal CT findings in patients with spontaneous intramural small bowel haemorrhage. We retrospectively reviewed the abdominal CT scans of six patients with known intramural small bowel haemorrhage. All of the patients had an underlying coagulopathy. All six patients underwent CT examinations without oral or intravenous contrast media. All six non-contrast CT scans showed hyperattenuation of the involved bowel segments, with thickened and dilated proximal small bowel. Therefore, patients who are clinically at risk for intramural small bowel haemorrhage should undergo a non-contrast CT scan of the abdomen prior to the routine oral and intravenous contrast-enhanced scan. In most cases the non-contrast scan will provide definitive diagnostic information which may not be evident from the contrast-enhanced scan alone.

Unenhanced helical CT for suspected acute appendicitis

OBJECTIVE

The purpose of this study was to determine the diagnostic accuracy of unenhanced helical CT scans in patients with a suspected acute appendicitis.

SUBJECTS AND METHODS

Over a 20-month period, 109 adult patients with suspected acute appendicitis were referred by the emergency department for an unenhanced helical CT scan. Each scan was obtained in a single breath-hold from the T12 vertebral body to the public symphysis using a 5-mm collimation and a pitch of 1.6. No patients were given oral or IV contrast media. The primary CT criteria for diagnosing acute appendicitis was the identification of an appendix with a transverse diameter larger than 6 mm with associated periappendiceal inflammatory changes. The presence of an appendicolith was considered a secondary finding as was isolated periappendiceal inflammation; however, appendicitis was not diagnosed in such patients unless an enlarged appendix was definitely identified. Final diagnoses were established by surgical or clinical follow-up and were compared with the original CT reports.

RESULTS

We found 66 true-negatives, 37 true-positives, four false-negatives, and two false-positives that yielded a sensitivity of 90%, a specificity of 97%, a positive predictive value of 95%, a negative predictive value of 95%, and an accuracy of 94%. An alternative diagnosis was established by an unenhanced helical CT scan in 24 patients (22%), which included cecal diverticulitis (seven patients), urinary tract disease (five patients), adnexal pathology (four patients), sigmoid diverticulitis (two patients), small bowel disease (three patients), right lower quadrant tumor (two patients), and an infected dialysis catheter (one patient).

CONCLUSION

Unenhanced thin-section helical CT is an accurate, effective technique for diagnosing acute appendicitis.

The thermodynamic advantage of DNA oligonucleotide 'stacking hybridization' reactions: energetics of a DNA nick

'Stacking hybridization reactions' wherein two or more short DNA oligomers hybridize in a contiguous tandem orientation onto a longer complementary DNA single strand have been employed to enhance a variety of analytical oligonucleotide hybridization schemes. If the short oligomers anneal in perfect head-to-tail register the resulting duplex contains a nick at every boundary between hybridized oligomers. Alternatively, if the short oligomers do not hybridize precisely in register, i.e. single strand regions on the longer strand are left unbound, gaps are formed between regions where short oligomers bind. The resulting gapped DNA duplexes are considerably less stable than their nicked duplex analogs. Formation of base pair stacking interactions between neighboring oligomers at the nicks that do not occur in gapped duplexes has been proposed as the source of the observed added stability. However, quantitative evidence supporting this hypothesis for DNA has not been reported. Until now, a direct comparison of the thermodynamics of DNA nicks versus DNA gaps has not been performed. In this communication we report such a comparison. Analysis of optical melting experiments in a well defined molecular context enabled quantitative evaluations of the relative thermodynamic difference between nicked and gapped DNA duplexes. Results of the analysis reveal that a nick may be energetically favored over a gap by at least 1.4 kcal/mol and perhaps as much as 2.4 kcal/mol. The presence of a 5'phosphate at a nick or gap fails to significantly affect their stabilities.

Non-contrast spiral CT for patients with suspected renal colic

Renal colic, defined as acute flank pain caused by the passage of a ureteral calculus, is a common condition, but the correct diagnosis may not be apparent clinically. For decades, intravenous urography has been the test of choice for evaluating patients with suspected renal colic. Recently, unenhanced (non-contrast) helical CT has been shown to be an accurate and highly effective examination which can be used instead of intravenous urography. In this article, the technique is reviewed in detail, including its advantages and potential pitfalls.

Optimization of thoracic spiral CT: effects of iodinated contrast medium concentration

PURPOSE

To determine the effect of varying iodine concentration on arterial enhancement and perivenous artifact during thoracic spiral computed tomographic (CT) scanning.

MATERIALS AND METHODS

One hundred thirty-eight outpatients received 15.0 g (n = 76) or 22.5 g (n = 62) of iodine (300 mg/mL iodine) while undergoing thoracic spiral CT. Patients received either undiluted contrast medium, 1:1 normal saline dilution, or 3:1 normal saline dilution. Contrast medium was injected at a flow rate determined to deliver the entire iodine dose within 40 seconds. Attenuation was measured within arteries and veins. Three blinded thoracic radiologists independently graded perivenous artifact and arterial enhancement.

RESULTS

Perivenous artifacts were statistically significantly reduced with successive iodine dilution (P < .002). Arterial enhancement was statistically significantly better with 15.0 g of iodine diluted 1:1 when compared with the same iodine dose undiluted or diluted 3:1 (P < .01). Arterial enhancement achieved with 15.0 g of iodine diluted 1:1 was not statistically significantly lower than that achieved with 22.5 g of iodine diluted 1:1 (P > .31); however, venous artifact was greater with 22.5 g of iodine (P < .004).

CONCLUSION

Reduced iodine concentration appears to diminish perivenous artifact and to result in improved arterial enhancement during thoracic spiral CT.

Trends in mortality and health behaviors: status of white and African-American women

A substantial proportion of mortality in the United States can be attributed to three major behaviors: using tobacco, maintaining an unhealthy diet, and being physically inactive. Using data from the South Carolina mortality files and Behavioral Risk Factor Surveillance System we were able to document state trends in mortality, cigarette smoking, physical inactivity, and unhealthy dietary practices. We found that, in spite of the declines in heart disease and stroke mortality noted nationally and in the state, the risk factor profiles for most women in South Carolina did not improve. This analysis further suggests that physical inactivity and dietary issues (excess caloric intake, low fruit and vegetable consumption) would be good choices for lifestyle interventions among women in South Carolina, not only because they ultimately affect mortality, but also because they exert interim effects on morbidity, including physical functioning and independence.

Health promotion practices among physicians

Personal belief concerning both the validity of health promotion and the physician's ability to influence patient behavior may affect how much effort a physician spends on health promotion strategies. We assessed these beliefs through a mail survey to physicians practicing in a predominantly rural southern state in 1987 (n = 83) and 1991 (n = 96). Response rates in both studies exceeded 75%. The instrument was obtained from similar studies conducted in Massachusetts in 1981 and Maryland in 1983. Between 1987 and 1991 we found slight improvements in the perceived importance of many health behaviors, but significant improvement was observed in the importance of reducing intake of dietary saturated fat (66% in 1987 to 80% in 1991; P < .05). Less than 10% of the physicians thought they could be "very successful" in modifying patients' behaviors. However, in 1991 physicians perceived that their ability to be "very successful" in helping patients to modify their behavior would increase threefold (8%-24% for exercise; 4%-18% for smoking) if given appropriate support. Although the type of appropriate support was not identified, the credibility of physician's advice in promoting health changes is important. These results suggest that efforts should be made to provide support to physicians who are inclined to discuss health behavior changes with their patients. Medical Subject Headings (MeSH): dietary fats, exercise, patient education, physician's practice patterns, smoking.

Unenhanced helical CT of ureteral stones: incidence of associated urinary tract findings

OBJECTIVE

The objective of this study was to determine the incidence of urinary tract findings associated with ureteral stones on unenhanced helical CT scans of patients with acute renal colic.

MATERIALS AND METHODS

One hundred forty-one consecutive patients with suspected renal colic were referred by the emergency department for a helical CT scan that was obtained without oral or IV contrast. The CT scans of 54 of these patients were interpreted as positive for ureteral calculi, and these CT scans were reviewed retrospectively. The size and location of each ureteral calculus and of any concurrent urinary tract calculi were recorded. The presence or absence of hydronephrosis, hydroureter, perinephric edema or soft-tissue stranding, and periureteral edema was also noted.

RESULTS

We reviewed the original 5-mm axial images from the 54 CT scans. Calculi were present in the proximal, mid, and distal ureter in eight, four, and 14 patients respectively, and at the ureterovesicular junction in 28 patients. Only two patients had more than one ureteral calculus, and none had a contralateral ureteral calculus. Concurrent renal parenchymal and/or nonobstructing calculi in the renal pelvis were seen in five patients with proximal, mid, or distal ureteral stones and in 16 patients with ureterovesicular junction stones. Hydronephrosis was found in 37 patients, hydroureter in 36 patients, and perinephric soft-tissue changes in 35 patients. Periureteral edema could not be evaluated in the 28 patients with ureterovesicular junction calculi because of the adjacent bladder, but periureteral edema was clearly seen immediately adjacent to the ureteral stone in 17 of the other 26 patients. Only two of the 54 patients had no evidence of hydronephrosis, hydroureter, or perinephric soft-tissue changes.

CONCLUSION

In patients with ureteral calculi imaged with unenhanced CT for acute renal colic, associated findings included hydronephrosis, hydroureter, perinephric soft-tissue changes, and periureteral edema. These common findings provided supportive evidence that an acute obstructive process was present.

Diagnosis of pancreatic injury after blunt abdominal trauma

Expeditious diagnosis and treatment of pancreatic injury continues to elude the trauma surgeon and radiologist. Missed or underestimated pancreatic injury is responsible for a high level of morbidity and mortality after blunt or penetrating trauma. Unfortunately, inappropriate therapy can lead to devastating consequences such as severe endocrine or exocrine insufficiency. Abdominal CT is currently the imaging method of choice for evaluating patients with blunt trauma. This article reviews the constellation of CT findings that the radiologist must rely on to establish the diagnosis of pancreatic injury.

Increased detection of hepatitis C virus infection in commercial plasma donors by a third-generation screening assay

BACKGROUND

Routine screening of blood donations with second-generation hepatitis hepatitis C virus (HCV) assays has substantially reduced the occurrence of posttransfusion hepatitis. However, following the development of third-generation assays, several studies indicated that these assays may identify HCV-infected individuals who are not identified by second-generation assays.

STUDY DESIGN AND METHODS

The sensitivity of a third-generation HCV enzyme-linked immunosorbent assay (ELISA-3) was compared with a second-generation ELISA (ELISA-2) in a side-by-side study of 9936 commercial blood donors. ELISA-reactive specimens were subjected to supplemental analysis by third-generation recombinant immunoblot assay and polymerase chain reaction.

RESULTS

ELISA-3 demonstrated greater sensitivity than ELISA-2, detecting 1 additional recombinant immunoblot assay-positive specimen per 2000 tested. ELISA-3 also detected 1 additional HCV-infectious polymerase chain reaction-positive unit among approximately 10,000 units screened.

CONCLUSION

The incremental sensitivity achieved with ELISA-3 can be expected to eliminate approximately 20 infectious donations per week among those made by commercial donors in the United States. In accordance with previous studies, most of the improved sensitivity of ELISA-3 derives from its increased detection of anti-c33c (NS3), rather than from the inclusion of HCV antigen NS5.

Predictors of adopting leisure-time physical activity among a biracial community cohort

Literature on the correlates and predictors of leisure-time physical activity among African-American population is sparse. This cohort study assessed correlates of leisure-time physical activity (specific large muscle activities during the past month at least three times a week) in a biracial population in 1987 and predictors for the adoption of this behavior 4 years later among those initially inactive. Random digit dialing methods were used to identify residents of two South Carolina communities in 1987. In 1991, 3,223 of these residents were resurveyed (62% response rate). In general, the correlates of leisure-time physical activity (education, > or = 12 years; nonsmoking; weight loss behaviors; and physician advice) were similar for each sex and race group. In 1987, the definition of leisure-time physical activity was not met by 831 (54% of 1,542) white women, 374 (76% of 489) African-American women, 586 (59% of 991) white men, and 126 (63% of 201) African-American men. Among those who were inactive in 1987, 22-24% of white adults and African-American men and 14% of African-American women adopted physical activity 4 years later. Twelve years or more of education was a predictor among white women (risk ratio = 1.7, 95% confidence interval 1.2-2.6) and African-American women (risk ratio = 3.1, 95% confidence interval 1.4-6.9), but not among men. Having a physician discuss physical activity was a predictor among white women (risk ratio = 1.9, 95% confidence interval 1.3-2.7), African-American women (risk ratio = 1.7, 95% confidence interval 0.9-3.2), white men (risk ratio = 2.0, 95% confidence interval 1.3-3.1), and African-American men (risk ratio = 2.7, 95% confidence interval 1.0-7.6). These results highlight the strong effect of educational attainment on adoption of healthy behaviors and support the involvement of physicians to promote physical activity among all race and sex groups.

Regional localization of the putative cell surface receptor for HTLV-I to human chromosome 17q23.2-17q25.3

The gene for the cell surface receptor for HTLV-I, the etiologic agent of adult T-cell leukemia and HTLV-I-associated myelopathy, has been localized to distal human chromosome 17q. A panel of somatic cell hybrids containing fragments of human 17q as the only human genetic component was mapped with a set of 10 chromosome 17 probes and utilized to regionally localize the gene. When compared to the murine fibroblast fusion partner, L-M(TK-), and a hybrid cell line containing human chromosome 20, human 17q-containing hybrid cells bound high levels of both HTLV-I virions and the monoclonal antibody, Mab 34-23, which may be directed against the putative HTLV-I receptor. Additional experiments revealed that the human 17q-containing hybrids could also be more efficiently infected by cell-free HTLV-I virions than could the control cell lines. Western blot analyses of cell lysates showed that recombinant HTLV-I envelope gp46 protein and Mab 34-23 both bound to proteins of approximate MW 30 and 31 kDa which were found only in the hybrid cell lines which contained human chromosome 17q. The data suggest that the gene for the HTLV-I receptor is located on the distal region of human chromosome 17q demarcated by the tk-1 locus (17q23.2-17q25.3).

The validity of self-reported hypertension and correlates of hypertension awareness among blacks and whites within the stroke belt

Hypertension surveillance activities increasingly are relying on information obtained by self-report. However, limited information is available concerning the validity of such data, especially among populations residing within the stroke belt. We used interview information and blood pressure measurements from the South Carolina Cardiovascular Disease Prevention Project to determine the validity of self-reported hypertension and the correlates of hypertension awareness among 2,210 whites and 704 blacks who participated in the program in 1987. The sensitivity, specificity, positive predictive value, and negative predictive value of self-reported hypertension were 79%, 91%, 76%, and 93% among white women; 82%, 88%, 79%, and 89% among black women; 62%, 91%, 75%, and 85% among white men; and 72%, 89%, 78%, and 85% among black men, respectively. Groups with highest sensitivity included women, persons older than age 39 years, and those who had seen a physician for preventive care within the last year. Correlates of hypertension awareness included an older age, visit to a physician for preventive care, and a family history of high blood pressure. Among hypertensive blacks, overweight persons were substantially more likely than nonoverweight persons to be aware of their hypertension (odds ratio [OR] = 4.6, 95% confidence intervals [CI] = 1.9, 10.7 in black women and OR = 4.4, 95% CI = 1.0, 17.9 in black men). The validity of self-reported hypertension was relatively high in all race-sex groups. There is a need to increase hypertension awareness among hypertensive blacks who are not overweight.

The association between alcohol use and health behaviors related to the risk of cardiovascular disease: the South Carolina Cardiovascular Disease Prevention Project

OBJECTIVE

This study examines the relationship between alcohol use and health behaviors related to the risk of cardiovascular disease (CVD). In particular, we examined the relationship between alcohol use and leisure time physical activity, participation in community physical activity programs and behaviors used for weight loss. Numerous studies have found a "protective" effect of moderate alcohol consumption on the risk of CVD. However, most of these studies have not adequately controlled for potential confounding by health behaviors associated with alcohol use.

METHOD

We used descriptive and logistic regression analyses to examine cross-sectional survey data from 2,072 participants in the South Carolina Cardiovascular Disease Prevention Project.

RESULTS

After controlling for age, race, education and preexisting CVD, moderate and heavy drinkers who do not smoke were more likely than nondrinkers to report engaging in regular leisure time physical activity. The relationship between other health behaviors and alcohol consumption was less clear. Among men, moderate and heavy drinkers were no more likely than nondrinkers to participate in community physical activity programs; among women, moderate and heavy drinkers were more likely than nondrinkers to report this activity. Moderate drinkers were more likely than nondrinkers to report that they were attempting to lose weight, however this difference was not statistically significant.

CONCLUSIONS

These data suggest that at least some of the apparent protective effect of moderate alcohol consumption found in other studies may be due to differences between nondrinkers and drinkers with respect to physical activity and other health practices.

CT diagnosis of blunt pancreatic trauma: importance of detecting fluid between the pancreas and the splenic vein

OBJECTIVE

The purpose of this study was to determine the value of detecting fluid between the splenic vein and the pancreas on CT scans in the diagnosis of pancreatic injury after blunt abdominal trauma.

MATERIALS AND METHODS

We retrospectively reviewed the abdominal CT scans of 10 patients with surgical- or autopsy-proved pancreatic injury after blunt abdominal trauma. The finding of fluid interdigitating between the pancreas and the splenic vein was then studied along with the reported CT features of pancreatic injury. These included intraperitoneal fluid, fluid in the lesser sac, extraperitoneal fluid, pancreatic edema or hematoma, and thickening of the anterior renal fascia.

RESULTS

The CT scans of all 10 patients reviewed showed abnormalities suggesting pancreatic injury. Only 40% of patients showed all of the findings reported in the literature. Fluid interdigitating between the splenic vein and the pancreatic parenchyma was seen on CT scans in 90%.

CONCLUSION

Our experience suggests that fluid between the splenic vein and the pancreas is a helpful CT finding for the diagnosis of pancreatic injury after blunt abdominal trauma. This finding was easy to recognize and in the proper clinical setting directs attention to additional subtle findings of pancreatic injury.

Identification of a putative cellular receptor for HTLV-I by a monoclonal antibody, Mab 34-23

The ability of HTLV-I to infect cells is presumed to be dependent, in some part, on the attachment of the virus to a target cell via a specific cell surface receptor which is, as yet, unknown. Here we present evidence that a monoclonal antibody, Mab 34-23, inhibits the binding of HTLV-I to IL-2 and phytohemagglutinin-activated peripheral blood mononuclear cells and also inhibits virus entry into these cells. Analysis of a variety of target cells, including a human:mouse somatic hybrid which contains only human chromosome 17q, indicates that the binding of Mab 34-23 correlates with HTLV-I adsorption and entry. SDS-PAGE and Western blot analysis show that Mab 34-23 binds to four major proteins of MW 31, 45, 55, and 70 kDa and this binding can be inhibited by HTLV-I and not HIV proteins. HTLV-I virions bind to proteins of similar molecular weight and virus-binding to these proteins can be inhibited by preincubation with Mab 34-23. These data suggest that Mab 34-23 may identify a specific cell surface receptor(s) for HTLV-I.

Gilvocarcin V exhibits both equilibrium DNA binding and UV light induced DNA adduct formation which is sequence context dependent

The relative degree of both equilibrium binding and of ultraviolet light induced adduct formation for the antitumor antibiotic gilvocarin V with two hexaecamer DNA sequence isomers, d[ATATATAGCTATATAT]2 and d[AAAAAAAGCTTTTTTT]2, was assessed. The experiments reveal that gilvocarin V binds, under equilibrium conditions, and reacts, in the presence of exogenously applied UV light, more efficiently with the alternating purine:pyrimidine sequence hexadecamer than the homopurine:homopyrimidine duplex at identical gilvocarcin V to DNA duplex ratios. DNAse I digests of adduct containing duplexes derived from the d[AAAAAAAGCTTTTTTT]2 duplex, identified and isolated using gel shift assays employing denaturing polyacrylamide gels, confirm that gilvocarcin V adducts can be formed with thymine residues but suggest that adduct formation with either adenine or guanine residues is also possible.

Infection of peripheral blood mononuclear cells and cell lines by cell-free human T-cell lymphoma/leukemia virus type I

Previous studies of in vitro infection by human T-cell lymphoma/leukemia virus type I (HTLV-I) have required cocultivation of target cells with HTLV-I cell lines or vesicular stomatitis virus pseudotypes containing HTLV-I envelope proteins. We report here the development of a cell-free infection assay for HTLV-I. Target cells were incubated with purified, DNase-treated HTLV-I virions for 4 h at 37 degrees C. Target cell DNA was then analyzed for the presence of newly synthesized HTLV-I proviral DNA by the highly sensitive polymerase chain reaction. Using this assay system, we have been able to consistently detect in vitro infection of a variety of cellular targets by different HTLV-I isolates. Optimal infection required the presence of 10 micrograms of DEAE-dextran per ml. The assay was dose dependent with respect to virus input. In general, the amount of proviral DNA detected correlated with the level of HTLV-I receptors present on the surface of the target cells, as measured by fluorochrome-labelled HTLV-I binding. Finally, the specificity of the assay was confirmed by demonstrating that the cell line, L1q, a somatic cell hybrid containing human chromosome 17q, to which the gene for the HTLV-I receptor has been mapped, was susceptible to infection by HTLV-I, while the parental mouse cell line from which it was derived, LMTK-, which lacks human chromosome 17q, was not.

Variation in genomic Alu repeat density as a basis for rapid construction of low resolution physical maps of human chromosomes

Human DNA restriction fragments containing high numbers of Alu repeat sequences can be preferentially detected in the presence of other human DNA restriction fragments in DNA from human: rodent somatic cell hybrids when the DNA is fragmented with enzymes that cleave mammalian DNA infrequently. This ability to lower the observed human DNA complexity allowed us to develop an approach to order rapidly somatic hybrid cell lines retaining overlapping human genomic domains. The ordering process also generates a relative physical map of the human fragments detected with Alu probe DNA. This process can generate physical mapping information for human genomic domains as large as an entire chromosome (100,000 kb). The strategy is demonstrated by ordering Alu-detected NotI fragments in a panel of mouse: human hybrid cells that span the entire long arm of human chromosome 17.

Double-minute chromosomes as megabase cloning vehicles

Radiation-reduced chromosomes provide valuable reagents for cloning and mapping genes, but they require multiple rounds of x-ray deletion mutagenesis to excise unwanted chromosomal DNA while maintaining physical attachment of the desired DNA to functional host centromere and telomere sequences. This requirement for chromosomal rearrangements can result in undesirable x-ray induced chromosome chimeras where multiple non-contiguous chromosomal fragments are fused. We have developed a cloning system for maintaining large donor subchromosomal fragments of mammalian DNA in the megabase size range as acentric chromosome fragments (double-minutes) in cultured mouse cells. This strategy relies on randomly inserted selectable markers for donor fragment maintenance. As a test case, we have cloned random segments of Chinese hamster ovary (CHO) chromosomal DNA in mouse EMT-6 cells. This was done by cotransfecting plasmids pZIPNeo and pSV2dhfr into DHFR-CHO cells followed by isolation of a Neo + DHFR + CHO donor colony and radiation-fusion-hybridization (RFH) to EMT-6 cells. We then selected for initial resistance to G418 and then to increasing levels of methotrexate (MTX). Southern analysis of pulsed-field gel electrophoresis of rare-cutting restriction endonuclease digestions of DNA from five RFH isolates indicated that all five contain at least 600 kb of unrearranged CHO DNA. In situ hybridization with the plasmids pZIPNeo and pSV2dhfr to metaphase chromosomes of MTX-resistant hybrid EMT-6 lines indicated that these markers reside on double-minute chromosomes.

Antroduodenal manometry. Usefulness and limitations as an outpatient study

We performed fasting and postprandial recordings of antroduodenal manometry in 21 normal volunteers, 13 patients with insulin-dependent diabetes mellitus and gastrointestinal symptoms, and 11 patients with the irritable bowel syndrome. None of the patients or volunteers had previously undergone an intestinal intubation study. Recordings could not be obtained from four of the diabetic patients due to failure to intubate the pylorus. Catheter migration led to incomplete antral data in a further 21% of all recordings. Due to the wide variations demonstrated by the normal volunteers, parameters of either the migrating motor complex (MMC) or the fed response could not differentiate between either of the patient groups and/or the controls. Similarly, while abnormal patterns of either fasting or postprandial motility were common in the diabetic patients, manometry had a sensitivity of only 67% in comparison to the less invasive radionuclide gastric emptying study. Furthermore, manometry failed to identify any diagnostic abnormality in irritable bowel patients; in particular, the incidence of "clustered" contractions was similar in all three groups. We conclude that short duration antroduodenal manometry is of limited diagnostic usefulness due to the difficulties in pyloric intubation in the presence of a dilated stomach and the intrinsic variability in normal motor patterns, perhaps excerbated by the stressful effects of the procedure itself in tube-naive subjects.

An efficient technique for obtaining sequences flanking inserted retroviruses

Genomic mapping studies frequently employ retrovirus-mediated transfer of dominant selectable markers to specific target chromosomes. DNA probes containing sequences adjacent to inserted proviruses are valuable mapping tools in such studies. We have implemented a strategy for amplification of chromosomal sequences flanking the 5' LTR of MoMuLV-based vectors. Probes derived from these amplification products successfully differentiated murine versus human proviral localization in retrovirus-infected mouse-human chromosome 17q hybrid cells.

Actinomycin D induced DNase I hypersensitivity and asymmetric structure transmission in a DNA hexadecamer

DNase I cleavage rates and nmr chemical shifts are shown to change for DNA sequences distal to an intercalated actinomycin D molecule in a duplex hexadecamer upon drug binding. Both sets of observations suggest that the source of these changes is a DNA-mediated structural response. The nmr results imply the response is transmitted preferentially in a 5'-to-3' direction from the drug binding site. An inequivalent response of the two strands to a ligand-induced conformational change immediately suggests a mechanism for distinguishing the sense and antisense strands of DNA.

Specific cleavage of the yeast genome at 5'-ATCGATCGAT-3'

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Plasmid multimers as high resolution molecular weight standards for pulsed field gel electrophoresis

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