Biomedical subjects
D Blackburn
Publications and source records attributed to D Blackburn.
An eponymous reaction to a knife wound.
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Cephalexin tolerated despite delayed aminopenicillin reactions.
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Is bilateral ultrasound scanning of the legs necessary for patients with unilateral symptoms of deep vein thrombosis?
PURPOSE: The purpose of this study was to determine the necessity of bilateral lower-extremity venous duplex ultrasound scanning in patients with unilateral symptoms of deep vein thrombosis (DVT). PATIENTS AND METHODS: A retrospective review of 1080 bilateral venous duplex scans was performed. Patients were randomly selected from a total of 7922 studied between May 1998 and May 2000. Data on patient age, sex, comorbidity, and the reason for ultrasound scan were compiled. Forty percent (435/1080) of patients presented with unilateral symptoms of lower-extremity DVT. This group was further analyzed according to their status as inpatients or outpatients. RESULTS: DVT was diagnosed in 26.9% (117/435) of the patients. Of the inpatients found to have DVT, the thrombus was confined to the symptomatic leg in 23.8% (38/159), thrombus was present just in the asymptomatic leg in 8/159 (5.0%), and thrombus was found in both legs in 8/159 (5.0%). In the outpatient group, thrombus was confined to the symptomatic leg in 21.0% (58/276) and found in both legs in 1.8% (5/276). None of the 276 outpatients had DVT isolated in the asymptomatic leg. CONCLUSION: Routine bilateral lower-extremity venous duplex studies are not necessary in outpatients presenting with unilateral symptoms. In many outpatients, a single-limb study will suffice. If a patient is found to have a DVT on the symptomatic side, then we believe that a bilateral study is indicated. We do believe that routine bilateral scanning of inpatients remains justified. This algorithm may save technician time and increase vascular laboratory efficiency.
Preparation and Certification of K-411 Glass Microspheres.
The production and characterization of NBS K-411 glass microspheres in the 2-40 µm range for certification as NIST Standard Reference Material(R) 2066 (SRM(R)) are described. Quantitative analysis and heterogeneity testing of the microspheres were done with an electron probe microanalyzer-X-ray energy dispersive spectrometry (EPMA-EDS) automated particle analysis procedure. Results for the trimmed and normalized data produced mean compositions for the elements Mg, Si, Ca, Fe, and O (calculated from stoichiometry) that are in good agreement with the certified values for the K-411 bulk glass (NBS SRM 470 Glasses for Mineral Analysis), but with uncertainties about twice as large as those for the bulk material. Differences from the bulk are attributable to microsphere geometry as well as mass and size effects.
N- and C-terminal substance P fragments: differential effects on striatal [3H]substance P binding and NK1 receptor internalization.
N- and C-terminal substance P (SP) fragments increase striatal dopamine outflow at nanomolar concentrations. This contrasts with their low affinity for NK1 receptors. To explore this discrepancy, we investigated the interaction of SP and SP fragments with NK1 sites in fresh striatal slices, the same model used in the functional studies on dopamine outflow. [3H]SP bound specifically to one site (Kd = 6.6 +/- 0.9 nM; Bmax = 12.6 +/- 0.7 fmol/mg protein). [3H]SP binding was displaced by SP (IC50 = 11.8 nM), but not by SP(1-7) or SP(5-11), up to 10 microM. In contrast, 10 nM SP(1-7) or SP(5-11) induced significant internalization of the NK1 receptor, similar to that induced by SP. We suggest that SP fragments have high affinity for an NK1 receptor conformer which is different from that labelled by [3H]SP.
Mutation analysis of the WT1 gene in sporadic childhood leukaemia.
The 10 coding exons of the WT1 gene, from 39 bp upstream of the translation initiation codon to 12 bp downstream of the stop codon, were examined for point mutations in a panel of 48 sporadic childhood acute leukaemias using the single-stranded conformational polymorphism (SSCP) assay. The panel included 33 cases of acute lymphocytic leukaemia and 15 cases of acute myeloid leukaemia. This is the first study in which sporadic childhood leukaemias have been examined for WT1 point mutations across the entire coding region of the WT1 gene, however, no tumorigenic point mutations or small deletions or insertions could be identified in these patients. A previously described polymorphism in exon 7, resulting in an A to G transition in an arginine codon, was observed at a frequency of 21.5%, equivalent to that seen in the normal population. This study suggests that point mutations in the coding regions of the WT1 occur infrequently in leukaemias of childhood.
Feasibility of transgastric ultrasonography of the abdominal aorta.
PURPOSE: Transesophageal echocardiography provides detailed images of the thoracic aorta, but imaging of the abdominal aorta and its branches does not occur routinely when the transesophageal echocardiography transducer is advanced into the stomach. Transgastric aortic ultrasonography (TAUS) was investigated as an intraoperative procedure to determine whether transgastric imaging of the abdominal aortic, mesenteric, and renal arteries could be obtained and whether pathologic lesions of these arteries could be identified. METHODS: Twelve patients with diagnoses of aortic aneurysmal or occlusive disease, chronic mesenteric ischemia, or renal artery stenosis that required operative treatment were examined. Preoperative transabdominal duplex imaging was performed in all 12 patients. Transgastric B-mode and color-flow ultrasonography of the abdominal aorta and branches was performed as an intraoperative procedure with the patients under general anesthesia. After the abdomen was opened but before the vascular reconstruction was performed, the transesophageal transducer was advanced into the stomach and directed by the surgeon's hand to obtain an image of the underlying aorta and branches. TAUS images were compared with those obtained by standard transabdominal duplex imaging. RESULTS: TAUS provided high-resolution images of both aneurysmal and occlusive aortic disease. In all 12 cases the images of the aortic lumen, plaque, and thrombus obtained with TAUS had greater detail and better resolution than those obtained with transabdominal duplex imaging. The origins of the renal arteries were seen with TAUS in 23 of 24 cases, whereas transabdominal ultrasonography obtained images of the origins in only 6 of 24 cases (p < 0.01). In the five renal arteries and the one mesenteric artery with hemodynamically significant stenoses in which transabdominal ultrasonography identified the stenoses based on velocity criteria alone, TAUS visualized the occlusive plaque at the origin of the renal and mesenteric arteries. CONCLUSION: Intraoperative TAUS is feasible and may be useful for evaluating atherosclerotic disease of the abdominal aorta and renal arteries.
Post-radical prostatectomy penile blood flow: assessment with color flow Doppler ultrasound.
Cadaveric dissections have revealed that accessory blood vessels to the penis often arise near or through the apex of the prostate. These accessory vessels may be easily injured during radical prostatectomy. Increasing attention since the 1980s has focused on preserving potency after radical prostatectomy with a nerve sparing technique. However, many patients are impotent even after a nerve sparing procedure. An arterial, venous or psychological mechanism may be involved. A prospective study was designed to assess cavernous artery diameter, peak systolic flow velocity, penile blood flow, end diastolic flow velocity and resistance index preoperatively and postoperatively in patients undergoing radical prostatectomy. Ten patients with a mean age of 60 years were evaluated, of whom 8 underwent a unilateral nerve sparing procedure, 1 bilateral nerve sparing procedure and 1 bilateral nonnerve sparing procedure. Mean penile blood flow as calculated by the formula penile blood flow = peak systolic flow velocity x pi (diameter/2)2 increased 0.33 ml. per second (+26%) on the nerve spared side, while diminishing 0.68 ml. per second (-41%) on the nonspared side. Overall penile blood flow was diminished. End diastolic flow velocity increased on spared and nonspared sides after surgery. The resistance index for all radical prostatectomy patients diminished 7% from 0.83 preoperatively to 0.77 postoperatively (p = 0.16). While these findings were not statistically significant, they suggest that arterial insufficiency and corporeal venous occlusive dysfunction may be involved in sexual dysfunction after nerve sparing radical prostatectomy.
Mitosis and histopathology in rat liver during methylclofenapate-induced hyperplasia.
Liver hyperplasia was induced in rats by daily administration of methylclofenapate (25 mg/kg by gavage). An increase in the incidence of colchicine-arrested metaphases was observed with peaks occurring at 40 h (1.3%), 64 h (6.4%) and 84 h (6.8%) after the start of treatment. This response contrasted with the much larger (21.3%) peak in arrested metaphases at 36 h after partial hepatectomy, but was still unexpectedly large in comparison with the S-phase response to methylclofenapate reported in a previous study. Progressive hypertrophic histopathological changes were apparent during the whole course of treatment.
Noninvasive evaluation of the upper extremity.
Vascular problems of the arm and hand can be assessed by a number of noninvasive modalities that are chosen on the basis of the history and physical examination. For suspected upper-extremity ischemia, we begin with SLPs and velocity-waveform analysis. The former test will define the extent and approximate location of the disease process, and subjective assessment of the waveform will further determine the degree and location of occlusive disease. When digital ischemia is suspected, the Doppler examination combined with intermittent compression of the radial and ulnar arteries is valuable for defining the variable arterial anatomy of the hand and the patency of the common and proper digital arteries. The extent of distal ischemia can be assessed by digital pressures. Duplex scanning has been found to be of value in determining the source of upper-extremity micro-emboli, in imaging suspected aneurysmal changes, and for evaluating arteriovenous fistulae and bypass grafts. Cold testing is used to confirm the diagnosis of Raynaud's disease after excluding proximal occlusive disease. When symptoms suggest intermittent arterial obstruction, arterial compression at the thoracic outlet is assessed by monitoring the arterial waveform during a series of maneuvers that change the anatomy of the outlet. Although a combination of IPG and venous Doppler examination accurately identifies venous occlusion, we routinely use duplex scanning in this setting. In addition to providing both anatomic and hemodynamic information about the subclavian vein, the jugular vein and the junction of the innominate vein can also be studied. Because of its ability to image in a coronal plane, MRI scanning is another nonivasive study that we have found useful for evaluation of venous anatomy and patency of the subclavian, jugular, and innominate veins. Venous thrombosis, often the first manifestation of subclavian vein compression at the thoracic inlet, is best evaluated using duplex scanning.
How postpartum women explain their lack of obtaining adequate prenatal care.
The quality of life for infants and children is often dependent on the adequacy of the prenatal care pregnant women receive. From July through to December 1985, 15% of pregnant women in one Midwestern county were identified as having inadequate prenatal care. The purposes of the study were to identify and analyse the reasons women in that county gave for not obtaining adequate prenatal care. In addition, chi-square was used to determine the relationship between the reasons given and the three variables, age, time between knowledge of pregnancy and making an appointment for care, and source of payment. A convenience sample (n = 44) was used in a study over a 5-month period at three locations. The Health Belief Model was the conceptual framework for this study. Insufficient money to pay for care was the primary reason given for not obtaining adequate prenatal care (81%). Other reasons included motivational issues (45%) and access or lack of transportation (19%). There was a significant relationship (P = 0.05) with four reasons to the variable of age and with three reasons to both the variables of time and source of payment. The following recommendations were identified as a result of this research: the need for subsidized prenatal care and the need for a community-wide education campaign regarding the need for adequate prenatal care and the consequences of inadequate care. Prenatal care is sometimes not available to all in the United States in spite of the relationship of infant mortality and the quality of life for infants and children to adequate prenatal care.
Upper extremity arterial injury in athletes.
Between 1983 and 1986, 23 athletes were evaluated for arm and hand complaints. Eleven players had symptoms of thoracic outlet compression. Severe arm fatigue (eight patients) and finger ischemia (three patients) were the presenting symptoms. In the remaining 12 athletes, symptoms of hand ischemia were predominant. Noninvasive testing with Doppler ultrasonography and duplex scanning (positional testing and finger systolic pressure recording) and cold immersion were used to aid in diagnosis. In the 11 athletes with thoracic outlet compression, arteriography confirmed the finding with compression of the subclavian artery in five, the axillary artery in one, both subclavian and axillary arteries in two, posterior humeral circumflex artery in one, and subclavian aneurysm in two. Compression of the suprascapular artery was identified in four, the subscapular artery in two, and the posterior humeral circumflex artery in one. Thrombosis of a first baseman's ulnar artery and occlusion of the palmar arch in a frisbee player were documented by arteriography. Decompression of the thoracic outlet consisted of anterior scalenectomy in five, pectoralis minor muscle division in one, and resection of both muscles in two. Removal of cervical rib with interposed vein graft was performed in the two players with arterial aneurysm. Hand ischemia in the remaining athletes was treated conservatively with Dextran-heparin infusion for acute ischemia. Repeat noninvasive study of all players demonstrated absence of compression in their playing position, and all have resumed their playing careers. Hand ischemia in athletes can be evaluated noninvasively and treated conservatively. Resection of hypertrophied muscles to decompress the thoracic outlet together with release of branch artery compression in selected athletes promotes perfusion to arm and shoulder muscles and helps to avoid the catastrophic complication of repetitive trauma leading to sudden arterial thrombosis.
Metabolism of the antihypertensive agent 1,4-dihydro-2,6-dimethyl-4-(2-trifluoromethylphenyl)-3,5-pyridinedicarboxylic acid diethyl ester.
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Linen standardization is first step in shared laundry planning.
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Human immunodeficiency virus seroprevalence and risk assessment of a homeless population in Denver.
OBJECTIVE: TO determine the prevalence of human immunodeficiency virus (HIV) infection among the homeless of Denver and to describe behaviors in the homeless that may be associated with HIV infection. DESIGN: A cross-sectional cohort study. METHODS: From July 1990 through June 1994, the authors conducted an unlinked survey collecting demographic and risk exposure data, and from August 1990 through June 1992, a more detailed risk behavior survey was completed on persons who attended the largest homeless clinic in Denver. RESULTS: For the combined survey years, the overall seroprevalence rate in the unlinked survey was 0.9%. Men were more likely to be seropositive than women (1.3% versus 0.1%) (P < 0.001). Black and Hispanic men had higher seroprevalence rates than white men (3.1% and 2.2% versus 0.5%) (P < 0.001). Gay and bisexual men, men who were injection drug users, and men with partners at risk had a nearly fivefold higher seroprevalence rate compared to other risk groups (3.1% versus 0.7%, P < 0.001). During the 4 study years, 14% of homeless persons tested positive for tuberculosis. In the risk behavior survey, 41% of the clients reported previous injection drug use (since 1978), and 22% reported recent use (past 12 months); of this 22%, 16% reported sharing their works (needles and paraphernalia). Seventy percent of the study participants stated that they changed their sexual behavior, and 39% reported using condoms in the past 12 months. CONCLUSIONS: In this homeless Denver population, there is a low seroprevalence of HIV but a high rate of HIV risk behavior. Certain groups of homeless persons are at high risk for HIV infection, and targeted interventions are necessary.
Hyperoxaluria: an underestimated cause of rapidly progressive renal failure.
Hyperoxaluria is rarely considered as a cause of rapidly progressive renal failure. A case is reported of a patient in whom rapidly renal failure developed after subtotal small bowel resection. A diagnosis of calcium oxalate deposits nephropathy was confirmed by renal biopsy. This cause of renal failure may be underestimated and should be systematically searched for in all patients with malabsorption.