Effects of feeding rations with genetically modified whole cottonseed to lactating Holstein cows.

Two experiments were conducted to evaluate dry matter intake (DMI), milk yield, and milk composition from feeding rations that contained different sources of genetically modified whole cottonseed to Argentinean Holstein dairy cows. Twenty-four lactating multiparous Argentinean Holstein dairy cows were used in 2 experiments with a replicated 4 x 4 Latin square design, with cows averaging 565 kg body weight and 53 d in milk at the beginning of the experiments. Treatments in Experiment 1 were: Bollgard cotton containing the cry1Ac gene, Bollgard II cotton containing cry1Ac and cry2Ab genes, Roundup Ready cotton containing the cp4 epsps gene, and a control nongenetically modified but genetically similar cottonseed. In Experiment 2, two commercial sources, a parental control line, and the transgenic cotton containing both cry1Ac and cp4 epsps genes were used as treatments. All cows received the same total mixed ration but with different whole cottonseed sources. Cottonseed was included to provide 2.50 kg per cow daily (dry matter [DM] basis) or about 10% of the total diet DM. The ingredient composition of the total mixed ration was 32% alfalfa hay, 28% corn silage, 22% corn grain, 17% soybean meal, and 2% minerals and vitamins. In addition, genomic DNA was extracted from a subset of milk samples and analyzed by polymerase chain reaction followed by Southern blot hybridization for small fragments of the cry1Ac transgene and an endogenous cotton gene, acp1. No sample was positive for transgenic or plant DNA fragments at the limits of detection for the assays following detailed data evaluation criteria. The DMI, milk yield, milk composition, body weight, and body condition score did not differ among treatments. Cottonseed from genetically modified varieties used in these studies yielded similar performance in lactating dairy cows when compared to non-transgenic control and reference cottonseed.

Surgical treatment of Takayasu's arteritis.

Takayasu's disease is an unusual arteritis that affects young females. Stroke is a common presenting symptom usually due to sudden occlusion of one or more thoracic aortic arch arteries. The author recommends prophylactic bypass of involved aortic arch arteries to prevent strokes. Abdominal aortic involvement causes severe claudication of the lower extremities which can be treated by bypass originating from the thoracic aorta. Involved upper extremity arteries should be bypassed for ischemic symptoms for accurate blood pressure measurement to diagnose and treat hypertension. Renal artery involvement is common and best treated by percutaneous transluminal angioplasty. Surgical results are excellent with minimal morbidity and mortality. Anastomatic complications such as false aneurysms are unusual although anastomatic stenoses do occur.

The timing of carotid endarterectomy after acute stroke.

Evidence exists that carotid artery endarterectomy prevents a second stroke in those patients who initially present with a stroke. However, the timing of the operation is controversial. Some authors advise a delay of 6 weeks, and others recommend an early endarterectomy as soon as the patient is clinically stable. The clinical studies addressing this problem are retrospective and nonrandomized, providing no definite answers. But they do provide some guidance. It is probably safe to perform early endarterectomy in clinically stable patients with negative computed tomography (CT) scans. Delay is recommended for more serious neurological events with positive CT scans. Early operation may also be indicated in patients with a significant threatening carotid arterial lesion.

Takayasu's disease and temporal arteritis.

Takayasu's disease and temporal arteritis are similar entities that predominantly affect women. There are significant differences. Takayasu's disease is a rare disorder that affects the aorta and its main branches in young women, whereas temporal arteritis is a common disorder that affects small- to medium-sized arteries of elderly women. The pathology of Takayasu's disease extends to all three arterial layers, whereas in temporal arteritis the disease affects the media and adventitia less, with giant cells more prominent. The diagnosis of Takayasu's disease depends on clinical presentation and characteristics of angiography, whereas temporal arteritis is diagnosed by clinical findings and arterial biopsy. Steroids are only palliative in Takayasu's disease with a high incidence of recurrences, whereas steroids in temporal arteritis are curative with good long-term results. Finally, surgery plays an important role in the care of patients with Takayasu's disease, but is used infrequently in those patients diagnosed with temporal arteritis.

Avoiding complications of long-term venous access.

Indwelling venous catheters are invaluable for long-term chemotherapy, antibiotics, and hyperalimentation. However, their placement and chronic use can cause serious complications. This study was done to develop guidelines for minimizing complications of long-term vascular access. Complications associated with 355 lines placed in 297 patients were recorded prospectively at the George Washington University Hospital. Single or double lumen catheters were placed via the infraclavicular subclavian approach (126), external jugular cutdown (133), internal jugular cutdown (22), and cephalic vein cutdown (42). While catheters were malpositioned in 15 cases (5.2%), route of placement did not influence this adverse outcome. Pneumothorax occurred only in the subclavian approach (5.6%). Axillary vein thrombosis was significantly more prevalent in catheters placed via the subclavian vein (10.3%) compared with the external jugular (2.3%) P < 0.05 or cephalic (2.3%) vein. Line sepsis occurred in 28 instances; this was statistically associated with an abnormal white blood count and with the use of double-lumen catheters (double-lumen catheter sepsis = 18.4%, single lumen = 4.4%, P < 0.01). The morbidity of long-term venous catheters is affected significantly by the route of placement, the number of catheter lumens, and the pre-placement white blood count. As a result of our analysis, we recommend single-lumen catheter placement using the external jugular cutdown route whenever possible.

Experience with surgical treatment of Takayasu's disease.

We reviewed 28 patients with Takayasu's disease to determine the incidence of stroke and its relationship to the involvement of the thoracic aortic arch and its branches. We describe surgical experiences with 10 of the 28 patients who required 21 vascular surgical procedures for critical thoracic aortic arch arterial stenoses, upper and lower extremity ischemia, and renal artery stenoses. Four of the 28 patients initially had a stroke caused by occlusion of one or more thoracic aortic arch arteries. Six of the 10 patients underwent 7 bypass procedures for critical thoracic arch stenoses. All have remained free of stroke for 5 or more years. Four patients had five anastomotic stenoses or graft occlusions in late follow-up; the development of these stenoses did not relate to disease activity at the time of the operative procedure. All bypass grafts originating from the subclavian axillary artery developed anastomotic stenoses; no anastomotic stenoses occurred in bypass grafts originating from the ascending aorta. In contrast to other reports, no anastomotic false aneurysms occurred. Occlusions of major aortic arch arteries in Takayasu's disease cause stroke. Bypass of critically stenoses aortic arch arteries protects against stroke and is best performed with grafts originating from the ascending aorta. Anastomotic stenoses but not anastomotic aneurysms are common. This study suggests that aggressive surgical treatment can be performed with good results.

Arteriovenous fistula simulating arteriovenous malformation.

A 36-year-old man was thought (for 20 years) to have an arteriovenous malformation that could not be excised. Repeated ligations of proximal arterial supply to the vascular lesion were only transiently beneficial and may have caused a delay in correct diagnosis because of impaired angioaccess. Once it was discovered that he had an arteriovenous fistula--probably caused by a tonsillectomy at age 6--it was possible to occlude the fistula with detachable balloons. The mass and his headaches subsequently resolved. AV fistulas are caused by trauma. Growth of AVMs is often stimulated by trauma. Both lesions have pulsatile masses associated with overlying bruits. The differential diagnosis can usually be made by arteriography, since AV fistulas are acquired lesions with a single communication between an artery and a vein, whereas AVMs are congenital lesions with multiple, large arterial feeding vessels and numerous arteriovenous communications. Proper diagnosis is important, since AVMs are aggressive lesions that tend to regrow if not completely excised. AV fistulas will be cured if the single arteriovenous communication can be obliterated. Proper treatment for AV fistula is obliteration of the single arteriovenous communication, operatively or with occlusive balloons; treatment of AVMs--when possible--is excision of the entire mass, combined (on occasion) with preoperative embolization of the tumor mass. This case report emphasizes the importance of accuracy in the differential diagnosis between arteriovenous malformations and arteriovenous fistulas; moreover, it demonstrates both the ineffectiveness and deleterious consequences of proximal arterial ligation, since collateral development is enhanced and angiographic access is compromised.

Iliac arterial-enteric fistulas occurring after pelvic irradiation.

Fistulas from the iliac artery to the bowel constitute a condition that is often lethal. Excluding fistulas related to vascular grafts, a review of previously reported cases shows that they are most often due to atherosclerotic iliac aneurysms. Three unusual cases of this condition that occurred after high-dose pelvic irradiation for treatment of cancer are presented; in no case was recurrent tumor evident. These cases suggest that high-dose pelvic irradiation can predispose to the formation of iliac arterial-enteric fistulas, particularly if sepsis or inflammation develops. The definitive surgical management of these fistulas entails bowel resection, arterial ligation, and extra-anatomic bypass.

Regional nerve block for femoropopliteal and tibial arterial reconstructions.

Thirteen high-risk patients underwent lower extremity revascularization anesthetized with a regional nerve block technique. The sciatic, femoral, and obturator nerves were infiltrated with 1% lidocaine and 0.25% bupivacaine. Eight femoropopliteal and five femorotibial bypasses were performed for limb salvage (11 patients), disabling claudication (one patient), and popliteal artery aneurysm (one patient). Analgesia was adequate with only one patient who needed supplemental nitrous oxide. One patient died on the sixth postoperative day of a myocardial infarction. Regional nerve block is an effective anesthetic technique that should be considered if general or spinal anesthesia is inappropriate.

Anomalies of the inferior vena cava.

The inferior vena cava is formed by a complex process of embryogenesis during the sixth to tenth week of gestation. Improper completion of the process may result in four anatomic anomalies: duplication of the inferior vena cava, transposition or left-sided inferior vena cava, retroaortic left renal vein, and circumaortic left renal vein. The first two anomalies can be diagnosed by sonography and all four anomalies can be seen on CT scan of the abdomen. Duplication and transposition of the inferior vena cava should be further delineated by preoperative phlebography. Preoperative diagnosis of the anomalies should reduce the complication rate of abdominal aortic operations.

Transperitoneal approach and right retroperitoneal dissection for abdominal aortic aneurysm.

Most abdominal aortic aneurysms can be resected through a standard transperitoneal approach. In patients with large aneurysms, supra-renal extension of the aneurysm, those requiring renal reconstructive procedures and in patients who have had previous extensive intra-abdominal operations, alternative approaches have been recommended. We exposed the abdominal aorta in ten of these difficult patients using a midline transperitoneal incision and right retroperitoneal dissection that provided excellent exposure of the suprarenal aorta. We recommend this technique for performance of complicated abdominal aortic aneurysm resections.

Lytic therapy in the treatment of axillary and subclavian vein thrombosis.

The importance of individualized treatment of patients with primary and secondary axillary-subclavian vein thrombosis is described with special emphasis on the use of thrombolytic therapy. Nine patients were treated with streptokinase or urokinase. Balloon dilation of the axillary or subclavian vein and first rib resection were also selectively used. Of the five patients with primary axillary-subclavian thrombosis, three did not have symptoms after the thrombus was lysed. Two had successful lysis of the thrombus but later suffered a rethrombosis, one of which most likely resulted from an untreated stenosis. All four of the patients with secondary thrombosis had successful thrombolysis. Patients with primary axillary-subclavian thrombosis are usually young and as many as 40% continue to have intermittent upper extremity edema or pain. For this reason we believe aggressive attempts to reestablish normal venous return through the axillary and subclavian veins are warranted. Patients with secondary axillary-subclavian thrombosis usually require prolonged venous catheterization for chemotherapy or total parenteral nutrition. Since patency of major upper extremity veins is extremely important in these patients with secondary thrombosis, we believe that vigorous attempts to restore these venous access routes are indicated and appropriate.

Timing of carotid artery endarterectomy after stroke.

Carotid endarterectomy has been advocated to prevent further neurologic deterioration in patients who have had a stroke. Previous reports have shown that endarterectomy within 2 weeks of a stroke is associated with high morbidity and mortality rates presumably from hemorrhagic complications in the brain. Some recommend a 2- to 6-week waiting period after a stroke, but the safety of operation in the interval of time beyond 2 weeks has not been documented in the literature. The present study investigated the morbidity and mortality rates of 352 consecutive carotid endarterectomies. Three hundred three endarterectomies were performed on patients with symptoms other than stroke. Forty-nine endarterectomies were performed on patients with a deficit lasting more than 24 hours. Of these, 27 carotid endarterectomies were performed in an interval less than 5 weeks after initial stroke (early interval) and 22 operations were performed in a 5- to 20-week interval after stroke (late interval). Five strokes occurred in the 27 patients operated on within 5 weeks, an incidence of 18.5%; none of the patients operated on after 5 weeks exhibited worsening of their preoperative neurologic status. With the use of Fisher's exact test to compare these two intervals, the results were found to be significant (p less than 0.05). The cause of stroke in those operated on in the early interval was investigated by postoperative CT scans; in only one instance was there a hemorrhagic infarct of the ipsilateral hemisphere. The literature suggests that a variety of intracerebral vascular changes render the brain more susceptible to reinfarction soon after stroke. This study suggests an unstable situation in the 5-week interval following stroke that contraindicates carotid endarterectomy.

Vascular malformations.

Fourteen patients with hemangiomas or arteriovenous malformations treated with operative management are described. Particular emphasis is placed on the definition of terms and the methods of differentiating arteriovenous fistulas, hemangiomas, and arteriovenous malformations. Arteriovenous fistulas are acquired lesions consisting of a single communication. Hemangiomas are congential lesions that rarely pulsate or have an associated bruit; moreover by angiography they have multiple small feeding arterial vessels and histologically are composed of numerous thin-walled, but normal-appearing, blood vessels. Arteriovenous malformations are also congenital but they pulsate and have associated bruits; furthermore on angiography they have a number of larger arterial feeding vessels and histologically are composed of abnormal dysplastic vessels. Operative management of all lesions should be carefully planned and executed. Arteriovenous malformations and skeletal muscle hemangiomas will have a tendency to recur if not completely excised.

Priority of revascularization in patients with graft enteric fistulas, infected arteries, or infected arterial prostheses.

Patients with arterial infections, infected arterial prostheses, or graft enteric erosions or fistulas have high amputation and mortality rates after treatment. An unresolved therapeutic question is whether remote ("extra-anatomic") bypass should precede or follow removal of the infected artery or prosthesis. None of the ten patients reported here who had a remote bypass inserted first developed distal limb ischemia or infection of the remote bypass. Literature review of patients with aortic prosthetic infections revealed a mortality of 71% (10/14) if infected graft removal preceded remote bypass and 26% (6/23) if remote bypass was first. Patients with graft enteric erosions or fistulas had a mortality of 53% (40/75) if graft removal was first and 17% (5/29) if remote bypass was first. Subsequent infection of the remote bypass was rare. Therefore, when possible, remote bypass with a prosthetic graft should precede removal of an infected artery, an infected arterial prosthesis, a graft enteric erosion, or a graft enteric fistula.

The use of fluoroscopy with the C arm for femoral arterial embolectomy and cannulation of the popliteal trifurcation vessels.

Fluoroscopy with the C arm allows for the immediate assessment of distal arterial circulation following embolectomy. With the use of two embolectomy catheters, each one of the trifurcation vessels can be separately cannulated to remove additional thrombus. The technique described is not difficult and adds little time to the operative procedure.

Delayed arterial embolectomy.

Eight instances of delayed or late embolectomy are presented with a review of 241 additional patients from the literature. The time interval from clinical onset to embolectomy ranged from three days to eight weeks in our series and two days to seven weeks in the additional 12 series surveyed. One amputation and seven successful restorations of arterial pulses occurred in our series. One hundred and seventy-two viable extremities, 48 amputations and 30 deaths were reviewed among the additional series. Intraoperative arteriography and a direct operative approach to the distal arterial tree would improve the results for those patients who require a delayed embolectomy.