Atrazine Transport through a Soil-Epikarst System.

Row crop and livestock production contaminate soils and groundwater of the karst aquifers within south-central Kentucky's Pennyroyal Plateau. Transport of atrazine from field application to the epikarstic drainage system beneath a field with active row-crop farming was investigated. The Crumps Cave study site is a shallow autogenic drainage system with a recharge area of ∼1 ha that contains two epikarst drains (WF-1 and WF-2) which were monitored for atrazine, deethylatrazine (DEA), and deisopropylatrazine (DIA) concentrations from January 2011 to May 2012. Atrazine concentrations in both drains did not increase above winter background levels for nearly 2 mo after application when levels suddenly spiked and reached peak concentrations for the study during an event in May 2011. Atrazine, DEA, and DIA were detected in 100% of samples, and metabolites accounted for 54 to 94% of the monthly total loads, except in May 2011. Median dealkylated metabolite/atrazine ratios (DMAR) were ∼5:1 at both sites, and seasonal DMAR patterns corresponded with changes in soil temperature. These data support the hypothesis that a combination of sorption and degradation in the soil column above the epikarst controlled the transport of atrazine and its metabolites. This resulted in delayed atrazine transport after application and prolonged transport of atrazine and its weakly sorbed metabolites to the epikarst aquifer. Management practices that reduce herbicide inputs, such as diverse crop rotations, cover crops, and use of low-rate and strong-sorbing herbicides, would improve groundwater quality in areas of the Corn Belt with intensive row cropping on karst topography.

Insulin and extremity muscle mass in overweight and obese women.

BACKGROUND: Obesity disproportionately affects women, especially those of African descent, and is associated with increases in both fat and muscle masses. OBJECTIVE: Although increased extremity muscle mass may be compensatory to fat mass load, we propose that elevated insulin levels resulting from diminished insulin sensitivity may additionally contribute to extremity muscle mass in overweight or obese women. METHODS: The following measurements were performed in 197 non-diabetic women (57% black, 35% white; age 46±11 years (mean±s.d.), body mass index (BMI) range 25.0-57.7 kg m(-2)): dual-energy X-ray absorptiometry for fat and extremity muscle masses; exercise performance by duration and peak oxygen consumption (VO2 peak) during graded treadmill exercise; fasting insulin and, in 183 subjects, insulin sensitivity index (SI) calculated from the minimal model. RESULTS: SI (range 0.5-14.1 l mU(-1 )min(-1)) was negatively, and fasting insulin (range 1.9-35.6 µU ml(-1)) positively associated with extremity muscle mass (both P<0.001), independent of age and height. Sixty-seven percent of women completed 6 months of participation in a weight loss and exercise program: we found a significant association between reduction in fasting insulin and a decrease in extremity muscle mass (P=0.038), independent of reduction in fat mass or improvement in exercise performance by VO2 peak and exercise duration, and without association with change in SI or interaction by race. CONCLUSIONS: Hyperinsulinemia in overweight or obese women is associated with increased extremity muscle mass, which is partially reversible with reduction in fasting insulin concentration, consistent with the stimulatory effects of insulin on skeletal muscle.

Surveillance for recurrent stenosis after endovascular procedures. A prospective study.

Eighty-nine endovascular procedures were performed during a 1-year period. Techniques included balloon angioplasty (n = 50), laser-assisted balloon angioplasty (n = 32), and atherectomy (n = 7). Indications were claudication (65.2%), critical ischemia (30.3%), and failing bypass (4.5%). Preoperative evaluation included a history and physical examination, segmental limb pressures, and color duplex ultrasonography. Postoperative surveillance consisted of a history and physical examination, ankle-arm indexes, and color duplex examinations at 1-week, 1-month, and then 3-month intervals. All levels of aortoiliac and infrainguinal disease were treated. Immediate technical success rate was 89.8%. Recurrence rates by life-table analysis reveal a 9-month patency rate of 45.4%. Early results of this prospective study indicate that endovascular procedures are subject to significant restenosis rates. Restraint is advised concerning general acceptance of endovascular procedures pending critical study.

Management of infrainguinal occluded vein bypasses with a combined approach of thrombolysis and surveillance. A prospective study.

Intra-arterial thrombolysis with urokinase was attempted on 23 occluded infrainguinal vein bypasses. Lesions revealed by thrombolysis included 11 anastomotic stenoses, five midbypass stenoses, five native artery stenoses, and five unusable diffusely stenotic vein conduits. Adjunctive procedures performed immediately after successful thrombolysis included 10 local surgical revisions, five balloon angioplasties, and five new vein bypasses. Three nonanastomotic vein bypass stenoses and two common iliac artery stenoses were detected using a surveillance protocol in subsequent follow-up of patients with patent bypasses. Twelve-month patency following thrombolysis (including immediate failures) was 52.4%. The use of thrombolysis in the management of occluded vein bypasses allows the identification and correction of pathological lesions. Once revised, continued vein bypass patency may be improved with a surveillance program.

Technical note: in vitro evaluation of an in-line Doppler flow-metering system for carotid artery shunts.

Carotid artery shunts are used extensively during carotid artery surgery to maintain cerebral perfusion. Blood flow through such shunts may be compromised by thrombosis, incorrect placement, or inadvertent clamping of the shunt. Currently, however, no direct method exists to detect poor shunt flow that might precipitate cerebral ischemia. A carotid artery shunt system that continuously monitors blood flow rates has been developed. This system utilizes a Doppler crystal embedded in the wall of a silicone elastomer shunt. The crystal ranges through a "liquid lens" that enables it to be placed without violation of the shunt lumen. Because the crystal is at a fixed angle (45 degrees) to the axis of blood flow and the diameter of the lumen remains constant, a linear relationship should exist between flow rates and the Doppler velocity signal. This hypothesis was tested in vitro using a pulsatile pump and both a starch-water solution and whole blood. Doppler velocity meter readings were compared to timed volume collections over a wide range of flow rates. A direct linear relationship between the Doppler flowmeter and timed volume collections existed, and the system was accurate to within 4.7%. This device may be useful in laboratory studies of carotid shunt dynamics and in clinical practice for early detection of correctable shunt flow abnormalities that could lead to cerebral injury.

Intervening in severe physical child abuse cases: mental health, legal, and social services.

OBJECTIVE: To examine the child protection process in cases of severe physical abuse, to compare characteristics of the families with risk factors previously reported in the published literature, and to develop recommendations about the use of mental health professionals in such cases. METHOD: Reviewers examined 30 case records of severely physically abused children under age 5, nominated by child protection workers and mental health providers. The reviewers recorded demographic, clinical, and case process information such as mental health and other referrals, reunification status, and frequency of criminal prosecution. A case study was described. RESULTS: The parents displayed a range of psychological characteristics (e.g., depression, anxiety, personality disorders) and life problems (e.g., domestic violence, substance abuse, abused as child). The majority of parents denied the abuse. The children were very young (more than half under 6 months old) and many had difficult births or medical problems prior to the abuse. The most common services offered were individual psychotherapy and parenting classes. More than half of the children reunified with at least one parent within I year. Forty percent of the cases involved criminal prosecution. CONCLUSIONS: Reunification occurred more quickly and more often than expected based on the severity of the injuries. The system often relies on psychotherapy to correct the abusive behavior, even when the perpetrator remains unknown and specific risks such as substance abuse or domestic violence are present. The authors advise utilizing multidisciplinary teams for recommendations regarding reunification.

An adult development study of contextual memory.

This study tested the hypothesis that there is a relatively greater decrease in memory for contextual features than in memory for target information with increasing age. Young, middle-aged, and elderly adults were presented with a number of slides, each of which contained a word centered on a background composed of either a landscape/cityscape or a border design. One third of the subjects were told to remember the words, one third were told to remember the backgrounds, and one third were told to remember the word-and-background pairs. Recognition memory for both words, backgrounds, and word-and-background pairings was tested in all subjects. The interaction between age, instruction condition, and type of information tested was not significant. Thus, there was no support for the hypothesis that older adults have a greater deficit in contextual memory than in memory for target information when compared to younger adults.

CVS-1123, a direct thrombin inhibitor, prevents occlusive arterial and venous thrombosis in a canine model of vascular injury.

CVS-1123, low-molecular-weight, direct thrombin inhibitor was studied in an anesthetized canine model of arterial and venous thrombosis to determine whether thrombin inhibition could reduce the incidence of occlusive thrombosis in response to vessel-wall injury. The left carotid artery (LCA) and right jugular vein (RJV) were instrumented with a flow probe, intraluminal electrode, and critical stenosis. Either saline (n = 9), or CVS-1123 (n = 12) was administered in a loading dose of 2 mg/kg i.v., followed by an infusion (2.46 mg/kg/h for 180 min). Vessel-wall injury was initiated by applying a 300-microA anodal current to the intimal surface of the LCA and RJV. Platelet aggregation in response to gamma-thrombin remained inhibited by CVS-1123 for 8 h. The activated partial thromboplastin time (aPTT) was increased and remained elevated for the duration of the protocol. The prothrombin time (PT) showed an initial increase and then a rapid decrease after the infusion was discontinued. There was a twofold increase in the bleeding time (BT) at 2 h. The time to occlusion of the LCA was prolonged (380 +/- 22 min in the CVS-1123 group vs. 152 +/- 18 min in the saline group) with seven of 12 patent arteries at 8 h. Similarly, the time to occlusion for RJV was prolonged (415 +/- 16 min in the CVS-1123 group vs. 99 +/- 8 min in the saline group) with eight of 12 veins remaining patent at 8 h. CVS-1123 administration was associated with a decrease in the thrombus weights in both the LCA and RJV as compared with the saline-treated animals. In summary, CVS-1123 modifies the thrombogenic response to deep vessel-wall injury in both the arterial and venous circulations. The results suggest that CVS-1123 is an effective antithrombin and may offer a therapeutic alternative to current antithrombins in the management of arterial and venous thrombosis.

Correlation of experimental rCBF determinations in goats with flow measurements from a Doppler-modified carotid artery shunt.

A carotid artery shunt system has been developed that continuously monitors blood flow rates by embedding a Doppler crystal in the shunt wall. The crystal ranges through a "liquid lens" that enables it to be placed without violation of the shunt lumen. Because the crystal is at a fixed angle (45 degrees) to the axis of blood flow and the diameter of the lumen remains constant, a linear relationship exists between flow rates and the Doppler velocity signal. This shunt system was previously tested in vitro using a pulsatile pump and was found to be accurate to within 4.7% of the actual flow rate. In the present study, animal (goat) experiments were performed consisting of simultaneous carotid shunt flow and bilateral rCBF measurements by the radiolabeled microsphere technique to determine in vivo the accuracy of this Doppler modified shunt and to ascertain the ability of shunt flow to increase in the face of acute contralateral carotid occlusion. Data from five animals show that in vivo shunt flow can be recorded to within 13% of control rCBF and that shunt flow increases nearly 50% under conditions of distal demand (contralateral carotid occlusion). This device may prove useful in laboratory studies of carotid shunt dynamics and in clinical practice to quickly detect correctable shunt flow abnormalities.

A prospective study of the incidence and natural history of femoral vascular complications after percutaneous transluminal coronary angioplasty.

Over a 14-month period patients undergoing 144 percutaneous transluminal coronary angioplasty procedures were evaluated for the presence of complications at the femoral puncture site. After percutaneous transluminal coronary angioplasty each patient was examined by a surgeon, and then a color-flow duplex scan of the groin was obtained. On the initial scan eight pseudoaneurysms, three arteriovenous fistulas, one combined arteriovenous fistula-pseudoaneurysm, and one thrombosed superficial femoral artery were detected for a major vascular complication rate of 9%. Pseudoaneurysm formation was associated with the use of heparin after removal of the arterial sheath. Seven pseudoaneurysms (initial extravascular cavity size range 1.3 to 3.5 cm) were followed with weekly duplex scans, and all thrombosed spontaneously within 4 weeks of detection. The three patients with isolated arteriovenous fistulas were each followed for at least 8 weeks, and the arteriovenous fistulas persisted. Early surgical intervention for postcatheterization femoral pseudoaneurysms is usually unnecessary as thrombosis often occurs spontaneously. We would advocate an operative approach for pseudoaneurysms that are symptomatic, expanding, or associated with large hematomas. Iatrogenic femoral arteriovenous fistulas should be considered for elective repair, but this may be delayed for several weeks without adverse sequelae.

Endovascular canine anastomotic stenting.

The healing characteristics and morphological features of a trans-anastomotic endovascular multifilament flexible metallic stent (Wallstent, Schneider) were investigated in a canine end-to-end arterial model. Both femoral arteries of 12 conditioned mongrel dogs were exposed, then transversely divided and reanastomosed. One anastomosis was randomly chosen for stent placement. Stents were chosen to match the diameter of the femoral arteries and were 25 mm in unconstrained length. Animals were sacrificed at intervals of 3, 6, 9, and 12 weeks. The anastomotic segments were pressure perfusion fixed and sectioned. The cross-sectional luminal, intimal, and medial areas were calculated from computer digitized images of the individual sections. Data were analyzed by univariate repeated measures analysis of variance. Stented anastomoses had an increased luminal area as compared with the anastomosis of non stented sections (P < 0.002). However, stended segments had a significantly increased intimal area when compared to control segments in the same animal (P < 0.001). Stented anastomoses had a significantly increased lumen area over controls despite a marked intimal response to the stent.