Optimal resources for carotid endarterectomy

This review compares the results and costs of carotid endarterectomy (CE) done by a single surgeon over a 1-year period working at both a university hospital (UH) and a community hospital (CH). Hospital and financial records of 157 patients were reviewed, 78 at UH and 79 at CH. The patient populations were matched for age, associated illnesses, and presenting symptoms. The principles of patient management were identical at both hospitals except that shunting requirements were determined by electroencephalographic monitoring at UH. There were no differences in the complication rates, and the combined stroke/mortality rate was 0.6%. The cost of CE was 56% greater on a per patient basis at UH ($3918 versus $6126, p less than 0.001) and 23% greater on a per diem basis at UH ($611 versus $755, p less than 0.001). Patients stayed longer at UH (8.2 days versus 6.6 days at CH, p less than 0.03). These differences are largely explained by three types of delays at UH. First, patients with cardiovascular accidents at UH were kept in the hospital before surgery until maximum improvement occurred whereas patients at CH were allowed to convalesce at home before CE. Patients operated on after a cardiovascular accident spent an average of 17.6 days in UH while a similar group spent only 7.3 days in hospital at CH (p less than 0.03). Second, delays in obtaining angiograms of greater than 2 hospital days occurred in 28% of patients at UH compared with only 10% at CH (p less than 0.05). Third, delays in scheduling operating room time of greater than 2 hospital days occurred in 17% of patients at UH and in only 7% of patients at CH (p less than 0.05). When there were no delays, the cost of treating patients at each hospital was identical, $3483 at CH and $3520 at UH. UH must accept the fact that equally good results can be obtained at CH, and although the potential exists for equal costs at both types of hospitals, the CH provides the service at a lower cost. UH administrators must address these inefficiences if the UH is to compete effectively in the current marketplace.

The role of external carotid revascularization in the treatment of ocular ischemia

During the past 13 years, 16 patients with visual disturbances, ipsilateral internal carotid artery (ICA) occlusion, and external carotid artery (ECA) stenosis have had ECA reconstruction. Indications for operation included amaurosis fugax (AF) in five patients, AF and transient ischemic attacks in four patients, ischemic optic neuropathy in two patients, retinal artery occlusion in one patient, and blurry vision and scotomata in four patients. In 12 cases (75%), there were hemodynamically significant contralateral ICA lesions, including four contralateral ICA occlusions. EC endarterectomies were performed in 15 patients, whereas one patient was treated with a bypass graft. One transient neurologic event occurred in the perioperative period (6%). There were no deaths nor permanent neurologic deficits. Patients were followed up for periods of 1 to 60 months (mean 18.4 months). Two patients had AF postoperatively; in one instance, AF was associated with ECA thrombosis 53 months after operation. One patient had a transient ischemic attack when the ECA thrombosed 24 months after operation. This study demonstrates that visual symptoms can occur despite ipsilateral ICA occlusion. ECA revascularization is effective and can be performed with acceptable morbidity and mortality.

Revascularization of the distal profunda femoris artery in the reconstructive treatment of aortoiliac occlusive disease

The distal profunda femoris artery is frequently spared from atherosclerosis and can be used as a recipient vessel in the absence of a satisfactory common or superficial femoral artery. During a 15-year period 53 inflow procedures were done to the distal profunda femoris artery at a point more than 3 cm from its origin. The ankle-brachial systolic pressure index increased an average of 0.27 +/- 0.04 postoperatively. Limb salvage was achieved in 33 of 37 threatened extremities (89%) and claudication improved in 10 of 14 cases (71%). Symptomatic improvement was dependent on an open popliteal segment and a low profundapopliteal collateral index. The overall 4-year patency by life-table methods was 76%, with a patency of 100% for femoroprofunda crossover grafts, 96% for aorto- and ilioprofunda grafts but only 26% for axilloprofunda grafts. Bypass to the distal profunda femoris artery represents a viable alternative when the common and superficial femoral arteries are unsuitable for outflow, with results comparable to procedures done to a healthy common femoral artery.

Use and limitations of thrombolytic therapy in the treatment of peripheral arterial ischemia: results of a multi-institutional questionnaire

In an attempt to assess the efficacy of thrombolytic infusions for arterial ischemia, a questionnaire was distributed to 142 vascular surgeons. Data from 45 respondents who had experience with thrombolytic infusion in 623 patients were reviewed. A successful outcome was obtained in 313 of 623 patients (50.2%). Morbidity was significant, with hemorrhage requiring transfusion or operation in 125 cases (20.1%) and major amputation in 103 cases (16.5%). There were nine strokes associated with thrombolytic infusion (1.4%), six of which were fatal. Sixteen deaths were associated with thrombolytic therapy, for a mortality rate of 2.5% (16 of 623 patients). Analysis of results by grouping centers according to numbers of lytic infusions failed to show significant correlation with center experience. Furthermore, morbidity and mortality were seen in centers with both limited and extensive experience with thrombolytic infusion. The initial enthusiasm for thrombolytic infusion to treat arterial ischemia is not substantiated by our data. Carefully controlled prospective trials are needed before this method can be offered as an alternative to arterial reconstruction.

Clinical and technical factors influencing recurrent carotid stenosis and occlusion after endarterectomy

Carotid endarterectomy was performed in 152 patients during a 27-month period. The first 82 patients had primary closure of the arteriotomy, whereas the subsequent 70 patients underwent closure with Dacron patch angioplasty. Duplex scanning was undertaken postoperatively in 102 of these patients with a mean follow-up period of 17 months. Perioperative thrombosis occurred in two patients (1.3%), late postoperative recurrent stenosis in 14 patients (13.7%), and late postoperative occlusion in three patients (2.9%). Of the various factors investigated for their correlation with late recurrent stenosis or occlusion, only three were significant: the female sex (recurrent stenosis in 29% vs. 8%, p less than 0.05), a small (less than 4 mm) internal carotid artery (37% vs. 12%, p less than 0.05), and failure to close the arteriotomy with a patch (29% vs. 6%, p less than 0.05). The development of recurrent carotid lesions appeared independent of smoking history, antiplatelet therapy, use of a shunt, or extent of carotid plaque. These data suggest that patients with small internal carotid arteries, specifically female patients, are at greater risk for recurrent carotid stenosis. Patch angioplasty may decrease this risk and should be considered in these patients.

The position of the mental foramen: a comparison between the southern (Hong Kong) Chinese and other ethnic and racial groups

The anteroposterior position of the mental foramen in eighty-seven southern (Hong Kong) Chinese skulls was compared with that reported for other ethnic and racial groups. The average position was essentially in line with the longitudinal axis of the second premolar tooth, a result similar to that reported for other Mongoloid populations, just posterior to the position in Caucasoids and anterior to the position in Negroids. These observations do not support the statement made in the majority of textbooks on dental analgesia that the foramen is most commonly found between the apices of the premolar teeth.

Acute renal artery occlusion: when is revascularization justified?

Acute renal artery occlusion is an infrequently encountered entity, with a paucity of literature on which to form clinical decisions. During a 20-year period 35 patients were treated for acute renal artery occlusion as a result of embolism (13 patients), thrombosis of a stenosed vessel (16 patients), or trauma (six patients). Patients were treated operatively in 16 cases and nonoperatively in 19 cases. In patients with embolic occlusion, embolectomy was successful in the relief of hypertension but was ineffective in the restoration of renal function. In patients with thrombotic occlusion, thrombectomy and aortorenal bypass were successful in both the reduction of blood pressure and the retrieval of renal function. In this group, salvage was dependent on the presence of a reconstituted distal renal artery, irrespective of the operative delay. In patients with traumatic renal artery occlusion, return of renal function did not occur, despite reperfusion as early as 6 hours after injury. These data suggest that the period in which function of embolized or traumatized kidneys may be preserved has usually passed by the time the diagnosis of renal artery occlusion has been made. By contrast, operative therapy of thrombotic occlusion frequently results in return of renal function, irrespective of the delay in treatment.

Relative cariogenicity and in-vivo plaque-forming ability of the bacterium Streptococcus oralis in gnotobiotic WAG/RIJ rats

The rats, fed a high sucrose diet, were mono-infected with seven strains of Streptococcus oralis. Moderate levels of caries were induced by four strains, and three others induced low levels. Approximal lesions were induced by two strains; no buccal/lingual lesions were produced. Scanning electron microscopy showed that all strains colonized the tooth fissures, some strains producing a moderately abundant and dense plaque. The most cariogenic strains (PB178, PB180 and PB186) induced similar levels of caries to Streptococcus milleri.

Revision of failed infrainguinal bypass graft: principles of management

Our experience with 112 patients whose infrainguinal bypass grafts (IIBPGs) failed more than 30 days after insertion was reviewed. Cumulative patency rates (CPRs) after graft revision (GR) were 71% at 6 months, 62% at 12 months, 57% at 24 months, 54% at 36 months, and 46% at 48 months. CPRs of IIBPGs that failed more than 12 months after insertion were higher than those of grafts that failed earlier (60% vs. 36% at 36 months (p less than 0.05). Failure of the initial GR did not preclude a successful secondary revision. The 3-year CPR of the initial GR was 31% compared with 49% for secondary GR (p = no significance). The results of GR are significantly better when graft failure is diagnosed before graft thrombosis. Revision of the 37 hemodynamically failed but patent grafts resulted in a CPR of 89% at 12 months and 77% at 36 months compared with a CPR of 33% at 12 months and 26% at 36 months after revision of the 75 thrombosed grafts (p less than 0.01). Hemodynamically failed but patent grafts occurred in 36 of 68 patients (53%) with failed autogenous veins but only 1 of 44 patients (2%) with a failed prosthetic graft had GR before thrombosis of the graft. There is a significant improvement in early CPR when a new bypass graft is inserted as compared with original graft thrombectomy and angioplasty. The CPR for new bypass grafts at 6 and 12 months was 61% and 41%, respectively, compared with a CPR of 26% and 20% for the same time intervals with graft thrombectomy and angioplasty (p less than 0.05). The presence of thrombus in the outflow artery at the site of GR is a contraindication to anastomosis at that site even if arterial thrombectomy reestablishes backflow. When distal arterial thrombus was not present, the CPR after GR was 62% at 6 months, 42% at 12 months, and 33% at 36 months. When distal arterial thrombectomy was necessary, the CPR after GR was only 14% at 6 months and zero at 12 months (p less than 0.05).

Embolic lesions from the subclavian artery causing transient vertebrobasilar insufficiency

Thirteen patients with transient vertebrobasilar insufficiency caused by emboli from a proximal subclavian artery lesion were treated over a 5-year period. This group was characterized by the absence of significant carotid disease (12 of 13 patients) and equal arm pressures bilaterally in most patients (8 of 13 patients). An isolated supraclavicular bruit (12 of 13 patients) and a history of ipsilateral digital ischemia (5 of 13 patients) were common. Arch angiography demonstrated proximal subclavian lesions in 12 patients, with obvious ulcerations in 10 cases and thrombus in an old carotid-subclavian bypass graft in one case. Surgery directed at removal or exclusion of the lesion was successful in all cases. Isolated lesions in the subclavian artery can be a source of emboli into the vertebrobasilar circulation. These lesions are effectively treated by exclusion and vascular reconstruction.

Carotid endarterectomy for nonhemispheric cerebral symptoms: patient selection with ocular pneumoplethysmography

Carotid endarterectomy fails to ameliorate nonhemispheric cerebral symptoms in an unacceptably high proportion of patients, specifically those patients with minor, hemodynamically insignificant carotid lesions. Ocular pneumoplethysmography (OPG) has been shown to accurately predict the hemodynamic significance of carotid lesions, but its use has not been applied to the subset of patients with nonhemispheric symptoms. Preoperative OPG studies were obtained in 43 patients with nonhemispheric symptoms. Postoperatively, 72% of patients with OPG suggestive of hemodynamically significant carotid lesions were relieved of symptoms. By contrast, only 32% of patients with normal OPG were asymptomatic after carotid surgery (p less than 0.05, life-table methods, 24-month follow-up). These data suggest that OPG is a useful test to determine which patients with nonhemispheric cerebral symptoms will benefit from carotid revascularization.

Carotid endarterectomy in the elderly patient

Although the segment of the population at the highest risk for cerebral ischemic events is more than 75 years old, there has been hesitancy in performing carotid revascularization in these patients because of an increased risk of perioperative morbidity. Over a period of 54 months, 77 (16 per cent) of 470 carotid endarterectomies performed were upon patients more than 75 years old. There were no differences between age groups with respect to perioperative morbidity or mortality, with three strokes (3.9 per cent) and no deaths in the patients more than 75 years old and 12 strokes (3.1 per cent) and two deaths (0.5 per cent) in the patients less than 75 years old. Postoperative follow-up study ranged from 30 days to five years (a mean of 25 months) in elderly patients. The over-all three and five year survival rate was 78 and 60 per cent, respectively. No patient experienced a stroke during follow-up study. Recurrent symptoms developed in 18 per cent of the elderly patients at three years of follow-up study, and the occurrence was dependent upon the preoperative symptom category (hemispheric 10 per cent and nonhemispheric 33 per cent). We conclude that the low perioperative morbidity and mortality, and subsequent results of carotid endarterectomy in the elderly patient justify operative intervention when significant lesions are encountered.

The plastome of Citrus. Physical map, variation among Citrus cultivars and species and comparison with related genera

A physical plastome map was constructed for Citrus aurantium, and the plastomes of species and cultivars of Citrus and of two Citrus relatives were analysed by Southern blot-hybridisation of labelled total tobacco cpDNA to digests of total Citrus DNA. A resemblance was found between the plastomes of cultivars of C. limon (lemon), C. sinensis (orange), C. aurantium (sour orange), C. paradisii (grapefruit) and C. grandis (pomello). The plastomes of other Citrus types such as mandarin (C. reticulata) and citron (C. medico) differed from each other as well as from the plastomes of the aforementioned group. The plastomes of Poncirus trifoliata and Microcitrus sp. are distinct from each other as well as from the Citrus types.

Spinal cord ischemia following operations on the abdominal aorta

Spinal cord ischemia following operations on the abdominal aorta is considered an unpredictable event attributable to variations in spinal cord blood supply. Our experience with seven cases of spinal cord ischemia contradicts this hypothesis. All patients had a bifurcation graft implanted. Three patients had bilateral interruption of hypogastric circulation. Each had gluteal necrosis and two had left colon ischemia. Two patients had unilateral hypogastric ligation. In both of these patients, early postoperative hypotension preceded recognition of spinal cord ischemia. Two patients without known interruption of hypogastric flow had proximal side-to-end anastomoses placed in an atheromatous aorta. Intraoperative peripheral emboli occurred in one and postoperative visceral emboli occurred in the other patient. In the latter case spinal cord ischemia occurred late concomitantly with embolization. The surmised important details in patients' courses with spinal cord ischemia are (1) interference with pelvic blood flow (five of seven patients) severe enough in three cases to cause gluteal necrosis and (2) a high incidence of perioperative complications. Interruption of an anomalous spinal artery was probably not a factor as cord lesions were mostly distal and no case of spinal cord ischemia occurred after a cylinder graft was placed. Spinal cord ischemia is potentially preventable. Our experience reemphasizes the importance of hypogastric perfusion, the dangers of handling the atheromatous aorta, and the necessity for avoiding postoperative hypotension.

Clinical pharmacology of tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide, NSC 286193)

A pharmacokinetic study of tiazofurin was carried out in 13 patients treated in a phase I clinical trial of the drug and in 7 patients undergoing surgical resection of brain tumor (in conjunction with studies on penetration of drug into central nervous system tumors). Tiazofurin was found to be rapidly eliminated from the plasma and red blood cell fraction of both groups of patients with kinetics consistent with a two-compartment model of elimination. Operative conditions did not significantly change the pharmacokinetics of tiazofurin in CNS patients. Pharmacokinetics were linear over the dose range 500-2700 mg/m2. The data suggest that there is only a small degree of tissue binding of drug and that the drug is not concentrated by tissues. Uptake into RBC was rapid and elimination from RBC was essentially parallel to drug elimination from plasma. There was no evidence that RBC sequestration of drug contributes to toxicity. Much of the drug was excreted unchanged in the urine, but there was little correlation between creatinine clearance and plasma pharmacokinetics of tiazofurin, suggesting that renal tubular secretion may be a more important method of elimination than is glomerular filtration. Patients with high AUC values and low plasma clearance values were particularly prone to develop toxicity.

Chronic caffeine ingestion sensitizes the A1 adenosine receptor-adenylate cyclase system in rat cerebral cortex

Caffeine consumption causes significant physiologic effects due to its antagonism of adenosine receptors. The A1 adenosine receptor is coupled in an inhibitory manner to adenylate cyclase. To study the effects of chronic caffeine ingestion, rats were provided with 0.1% caffeine drinking solution for 28 d. The A1 adenosine receptor agonist radioligand [3H]phenylisopropyladenosine identifies two affinity states in control rat cerebral cortex membranes with a high affinity dissociation constant (KH) of 0.40 +/- 0.08 nM and low affinity dissociation constant (KL) of 13.7 +/- 3.9 nM, with 33% of the receptors in the high affinity state. In membranes from caffeine-treated animals, all of the A1 receptors are shifted to the high affinity state with a dissociation constant (KD) of 0.59 +/- 0.06 nM. Guanylyl-imidodiphosphate (10(-4) M) decreases binding by 43% in control membrane, with no change in KH or KL, while membrane binding in caffeine-treated animals decreases by 45% with a threefold shift in KD to 1.5 +/- 0.3 nM. Concomitant with the enhanced high affinity A1 receptor state and increased sensitivity to guanine nucleotides, membranes from treated animals show a 35% enhancement in (-)-N6-(R-phenylisopropyl)adenosine-mediated inhibition of adenylate cyclase compared with controls (P less than 0.03). Photoaffinity crosslinking the receptors with [125I]N6-2-(3-iodo-4-aminophenyl)ethyladenosine reveals that A1 receptors from both groups migrate as Mr 38,000 proteins. beta-adrenergic receptor binding with [125I]iodocyanopindolol shows a decrease in the number of beta-receptors from 233 +/- 7 fmol/mg protein in control membranes to 190 +/- 10 fmol/mg protein in treated membranes (P = 0.01). These data indicate that the adenosine receptor antagonist, caffeine, induces a compensatory sensitization of the A1 receptor-adenylate cyclase system and downregulation of beta-adrenergic receptors, and provides a molecular mechanism for the caffeine withdrawal syndrome.

Use of computerized cerebral tomography in selection of patients for elective and urgent carotid endarterectomy

The charts of 181 patients who underwent computerized cerebral tomography (CCT) prior to carotid endarterectomy were reviewed. Findings on cerebral tomography were correlated with clinical presentation, frequency of intraoperative changes in the electroencephalogram (EEG), and occurrence of postoperative neurologic deficits. In the elective group (154 patients), while there was a significant (p less than 0.001) increase of positive ipsilateral CCT findings in stroke patients, 36% of patients with clinical stroke had a negative CCT scan and 21% of patients who were clinically asymptomatic had a positive CCT scan. Results of CCT did not correlate with the incidence of EEG changes (p greater than 0.2) or postoperative stroke rate (3.2%) (p greater than 0.5). Results of urgent carotid endarterectomy were directly related to the findings on preoperative CCT scan. A negative CCT scan was associated with clinical improvement in 88% of patients, one case of neurologic deterioration (5.8%) and no mortality (p less than 0.05). Only 50% of patients operated on acutely with a positive CCT scan showed neurologic improvement while there was a 40% increase in neurologic morbidity and 10% mortality in this group (p less than 0.01). CCT plays a limited role in the preoperative evaluation of patients with clear-cut clinical evidence of thrombo-embolic stroke or transient cerebral ischemia. Findings on CCT scan were of no help prognostically in selecting patients for elective carotid endarterectomy. In contrast, CCT scans have been extremely helpful in planning therapy for patients with acute neurologic problems and evidence of significant extracranial vascular disease.

Ocular manifestations of carotid artery atheroma

Although carotid endarterectomy (CE) is recommended in appropriate patients with bifurcation atheroma for the prevention of stroke, these patients are also at risk for visual loss, either temporary or permanent. The presentations of patients undergoing 512 consecutive CEs were reviewed to determine the preoperative frequency and risks of ocular disturbances. Visual symptoms occurred in 131 patients (25%). Temporary, monocular blindness (amaurosis fugax, AF) was reported by 99 patients (19%). Concomitant neurologic symptoms were present in 33 (33%) of the patients with AF, and carotid artery stenoses of greater than 75% diameter were documented in 82 (83%) of these patients. No visual deficits were observed following operation. Permanent visual loss ranging from scotoma to complete blindness was documented in 32 patients (6.2%). The permanent deficits were due to retinal artery occlusions (RAO) in 20 patients (4%), ischemic optic neuropathy (ION) in eight patients (1.5%), and homonymous hemianopsia (HH) in four patients (0.7%). Visual loss occurred without any warning in 27 of these 32 cases (84%). The five cases with warning had multiple episodes of AF and then sustained RAO and blindness. Neurologic symptoms occurred concomitantly but not prior to visual symptoms in 7 of the 12 patients (58%) with ION and HH. Stenoses greater than 75% were present in 22 of 32 cases (69%) and in every case of ION. Operation had no effect on the visual deficit. Permanent visual loss occurred in a significant number of patients with carotid atheroma (6.2%). Warning in the form of visual prodroma is uncommon in these patients (16%).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute thrombosis of abdominal aortic aneurysm subsequent to Heimlich maneuver: a case report

We report a case of acute thrombosis of an abdominal aortic aneurysm secondary to a correctly applied and successful Heimlich maneuver. Although the Heimlich maneuver is generally safe and effective, this possible catastrophic consequence needs to be recognized.

Benefits, shortcomings, and costs of EEG monitoring

A 5-year experience with 562 carotid endarterectomies, using electroencephalogram (EEG) monitoring and selective shunting, was reviewed. EEG changes occurred in 102 patients (18%). The frequency of EEG changes, as related to cerebral vascular symptoms, was as follows: transient ischemic attacks, seven per cent (19/259); completed strokes, 37% (36/98); vertebral basilar insufficiency, 24% (32/135); asymptomatic, 21% (15/71). Patients with contralateral carotid occlusion exhibited EEG changes in 37% (28/76) of operations. Fifteen patients suffered perioperative strokes (2.6%). Nine of the 15 were associated with a technical problem of either thrombosis of the internal carotid artery (five) or emboli (four). Technical problems were more common when shunts were used (five per cent) than when they were not (0.9%). Patients who suffered strokes prior to surgery were more at risk to develop a perioperative stroke (three per cent) than those not suffering prior strokes (0.3%). The EEG did not change in three patients who had lacunar infarcts prior to surgery and who awoke with a worsened deficit. Our series does not clearly establish the advantages of EEG monitoring, which is expensive (+375/patient) and may not detect ischemia in all areas of the brain. However, the use of shunts may introduce a risk of stroke due to technical error that is equal or greater than the risk of stroke due to hemodynamic ischemia. Since the need for protection is unpredictable by angiographic or clinical criteria, the benefit of EEG monitoring may be in reducing the incidence of shunting in those patients whose tracing remains normal after clamping. The decision to shunt, however, when there is electrical dysfunction after carotid clamping should be based not only on the EEG but also on the clinical signs and computed tomography (CT) scan. Our data does not show a net benefit in selective shunting unless the patient has sustained a stroke prior to surgery.

Use of oculopneumoplethysmography (OPG-Gee) following carotid endarterectomy

Oculopneumoplethysmography (OPG-Gee) was performed pre- and postoperatively in 100 patients undergoing carotid endarterectomy and 14 patients undergoing nonendarterectomy procedures (aortofemoral or carotid-subclavian bypass). Absolute differences in ocular systolic pressure (OSP) were determined and results were compared with previous criteria. Twelve examinations yielded abnormal findings in the endarterectomy group. Seven patients had associated neurologic deficits and six had occlusion confirmed at reexploration. Five patients were without symptoms; two with profound depressions in OSP were reexplored and thrombosis confirmed whereas three with moderate (15 to 30 mm Hg) depressions in OSP were followed up and remained asymptomatic. Values of OSP were related to the status of the contralateral carotid artery. In the nonendarterectomized patients OSP did not change with general anesthesia or carotid clamping. OPG-Gee is a useful test to screen for postoperative carotid thrombosis. It helps select symptomatic patients with occlusions who might benefit from early reexploration. In asymptomatic patients a profound drop in OSP identifies early occlusion and may be used alone or in concert with angiography to select patients for reoperation.

Isolation and point of action of a factor from Escherichia coli required to reconstruct translation

To study the mechanism of translation we have attempted to reconstruct the process from purified components. Protein synthesis was programmed by the RNAs of wild-type or amber mutants of bacteriophages f2 or MS2. Translation programmed by MS2 or f2am3 RNA does not occur using ribosomes, precharged aminoacyl-tRNAs, and the sum of the purified proteins involved in initiation (initiation factors; IF-1, IF-2, and IF-3), propagation (elongation factors; EF-Tu, EF-Ts, and EF-G) and termination (release factors; RF-1 or RF-2) of protein synthesis. The requirement for a protein called W was demonstrated. Protein W was purified free of all translation factors, activating enzymes, and other proteins such as the RR, "rescue," and EF-P implicated in translation. The stimulation of propagation by W depended on the position of the amino acid residue to be added in the synthesis of the NH2-terminal hexapeptide of the coat protein. In the reconstructed system, with the sum of all translation factors but in the absence of W, only dipeptides and smaller quantities of tripeptides were synthesized under the direction of f2am3 RNA. W stimulated the synthesis of the hexapeptide, fMet-Ala-Ser-AspNH2-Phe-Thr directed by this RNA. In addition, W stimulated ejection of non-cognate tRNAs that bind to ribosomal particles.

Relationship of adhesion in vitro and cariogenicity of oral Streptococcus species in germ-free rats

Thirty-two strains of Streptococcus spp., of known cariogenicity in the gnotobiotic WAG/RIJ rat, were tested for their in vitro adhesion properties. Computerized image analysis measured percentage coverage by, and clump size of, cells adhering to saliva-coated glass. An analysis of variance revealed significant differences for percentage coverage for the majority of species-pairs. There were fewer significant differences for mean clump size between species-pairs. Within the Strep. mutans group there was a highly-significant difference between Strep. mutans/Strep. cricetus (p less than 0.01) with respect to mean clump size. There was a significant correlation between cariogenicity and percentage coverage (p = 0.05) but not clump size (p = 0.359) for pooled strains of Strep. mitis and Strep. sanguis combined.

The comparative cariogenicity and plaque-forming ability in vivo of four species of the bacterium Actinomyces in gnotobiotic rats

Gnotobiotic WAG/RIJ rats on a high sucrose diet were monoinfected with 12 strains of Actinomyces spp. Moderate levels of caries were induced by a single strain of Actinomyces naeslundii and low levels by two strains of Actinomyces viscosus, three strains of A. naeslundii and one strain of Actinomyces israelii. No caries was induced by single strains of A. viscosus and A. israelii or by three Actinomyces odontolyticus strains. Only fissure caries was observed. Scanning electron microscopy showed that all strains colonized the fissures and most colonized the lingual surface of the teeth, but to a limited extent. Production of abundant and dense plaque was not always accompanied by caries.

The cariogenicity of sucrose, glucose and maize starch in gnotobiotic rats mono-infected with strains of the bacteria Streptococcus mutans, Streptococcus salivarius and Streptococcus milleri

Twenty-one-day-old weanling gnotobiotic WAG/RIJ rats were mono-infected with Streptococcus mutans NCTC 10832, Streptococcus salivarius JMB or Streptococcus milleri NCTC 11169, and maintained on a high carbohydrate diet containing sucrose, glucose or maize starch for 21-days. Fissure caries developed with all combinations of streptococcal strain and carbohydrate except maize starch/Streptococcus salivarius JMB. Caries incidence was highest with Streptococcus mutans NCTC 10832. For all species, the ranking of carbohydrates by cariogenic potential was sucrose greater than glucose greater than maize starch.

Abdominal aortic aneurysm: the case for elective resection

Abdominal aortic aneurysms are one of the more common problems faced by the vascular surgeon. A review of 898 aneurysms resected at the University of Rochester from 1955 to 1982 revealed a sequential decrease in mortality for elective surgery from 13% in 1955 to 1965, to 8.4% from 1966 to 1973, and 5.6% in the last 8 years. Mortality for resection of ruptured aneurysms remained high (70%). The incidence of ruptured aneurysms has not changed significantly in the last 16 years. For 1980 and 1981 we calculated the hospital costs of surgical treatment of abdominal aortic aneurysms. The mean total cost after elective resection was +10,114 compared with +18,223 after rupture. Increased costs after rupture reflected both a longer stay and more intensive and expensive medical care. Using discharge data from U.S. hospitals in 1979, we extrapolated our cost and mortality data to a national level. Assuming a mortality rate for elective resection of 5% and a mortality rate for resection after rupture of 50%, we estimated that in 1979 +50 million and over 2000 lives could have been saved if patients with abdominal aortic aneurysms had been identified and subjected to elective resection. The incidence of ruptured abdominal aortic aneurysms remains unacceptably high. Mortality from this disease can best be reduced by increased physician awareness and prompt surgical referral.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute acalculous cholecystitis complicating abdominal aortic aneurysm resection

Acute acalculous cholecystitis developed in six patients recovering from repair of an abdominal aortic aneurysm. All patients were men with significant concurrent medical illnesses, and three patients had undergone operation for a ruptured aneurysm. Symptoms appeared at a mean of 3 weeks postoperatively and consisted of right upper quadrant pain, fever, leukocytosis, and slight elevation of liver function test results. Treatment consisted of cholecystostomy (three patients) or cholecystectomy (three patients), with an overall mortality rate of 50%. When cholecystitis is suspected after aortic aneurysm repair, early confirmation of the diagnosis should be obtained with ultrasound or a technetium hepatobiliary scan and cholecystostomy or cholecystectomy undertaken if the patient does not rapidly improve with medical management.

Carotid endarterectomy for nonhemispheric symptoms: predictors of success

Over a 4-year period 335 patients underwent 402 carotid endarterectomies: 227 (56%) for carotid territory symptoms, 107 (27%) for nonhemispheric symptoms, and 68 (17%) for asymptomatic lesions. In 317 four-vessel arteriograms, proximal subclavian and/or vertebral lesions were found more frequently in the nonhemispheric group (80 of 97, or 82%) than in the carotid territory group (110 of 220, or 50%; p less than 0.05). EEG changes after carotid clamping occurred more often in the nonhemispheric group (15 of 65, or 23%) than in the carotid territory group (16 of 140, or 11%; p less than 0.001). The perioperative stroke rate was independent of whether nonhemispheric or carotid territory symptoms were present preoperatively (2.8% vs. 3.5%). Follow-up ranged from 1 month to 4 years. Carotid endarterectomy was successful in ameliorating symptoms in patients meeting the criteria for "classic" vertebrobasilar insufficiency more often than in patients not meeting these criteria (73% vs 43% asymptomatic at 24 months). Carotid endarterectomy was successful in patients with carotid stenoses of greater than 60% diameter reduction more often than in patients with smaller stenoses (77% vs. 36% asymptomatic at 24 months). Carotid endarterectomy appears justified in patients with nonhemispheric symptoms when classic vertebrobasilar insufficiency and/or hemodynamically significant carotid stenoses are present.

Blunt trauma to the carotid artery with transient deficit and early repair

Blunt trauma to the carotid artery is an uncommon but easily overlooked source of neurological deficit. The prompt diagnosis and angiographic definition of carotid-artery injuries can allow early operative intervention in these potentially devastating lesions. We describe a case report of blunt trauma with transient deficit in a patient who underwent direct repair via Dacron-patch angioplasty.

In-vivo dental plaque-forming ability and relative cariogenicity of the bacteria Streptococcus mitis and Streptococcus sanguis I and II in mono-infected gnotobiotic rats

Sixteen strains of Streptococcus mitis, Streptococcus sanguis I and Strep. sanguis II were tested for cariogenic potential and in-vivo plaque-forming ability in a gnotobiotic WAG/RIJ rat test system. All strains produced far less fissure plaque in vivo than strains of Streptococcus milleri or Streptococcus mutans. There was less extracellular matrix around cells of Strep. mitis or Strep. sanguis than around Strep. mutans, in the fissures. Dense sheets of cells were observed only with Strep. mutans. Some localized colonization of exposed smooth surfaces occurred with most strains. Strep. mitis produced no caries in three tests, low-caries scores in two tests and high-caries scores in one test. A single strain of Strep. mitis produced a highly-cariogenic variant able to ferment raffinose. Strep. sanguis I induced low-levels of caries in 12 tests; one test of NCTC 7865 produced moderate levels of caries, and another test of 311 produced no caries. Strep. sanguis 311 was dextran-negative. Strep. sanguis II strains induced no caries in three tests, low caries scores in six tests and moderate levels of caries with Strep. sanguis 402. No strain of Strep. mitis or Strep. sanguis was able to induce smooth-surface lesions.

The production of dental plaque and caries by the bacterium Streptococcus salivarius in gnotobiotic WAG/RIJ rats

The abilities of ten strains of Streptococcus salivarius to colonize rat molars and to induce caries were determined using mono-infected germ-free rats. Scanning electron microscopy revealed the production of micro-colonies and spheroids by Strep. salivarius on exposed surfaces of molar teeth, and abundant dense plaque formation in fissures. Most strains colonized fissures and smooth surfaces as effectively as Streptococcus mutans NCTC 10832, yet produced no buccal or lingual lesions. The four K- strains of Strep. salivarius produced more approximal lesions than the K+ strains but fewer lesions than Strep. mutans. All but one Strep. salivarius strain fell into the high-caries category, together with Strep. mutans. They were all more cariogenic than either Streptococcus milleri NCTC 11169 or Streptococcus faecalis 47.

Is routine angiography necessary prior to carotid endarterectomy?

The records of 111 consecutive patients undergoing evaluation for possible carotid endarterectomy at the University of Rochester were reviewed. All patients had noninvasive evaluation (oculoplethysmography-Gee and direct, continuous-wave Doppler ultrasonography) as well as selective carotid angiography. Patients were grouped by clinical presentation to ascertain the relative importance of angiography in determining the need for surgery. Arteriography added nothing to clinical and noninvasive evaluation in over two thirds of patients with hemispheric cerebral symptoms or asymptomatic carotid bruits. In contrast, we found that almost all patients with nonhemispheric symptoms required angiography for adequate evaluation prior to surgery. The implication of these findings on preoperative evaluation of patients with carotid surgery is discussed.

Pseudoocclusion of femoropopliteal bypass grafts

Pseudoocclusion has occurred when a patent graft is mistaken for a thrombosed graft, often because of reduced inflow. We reviewed 13 patients with pseudoocclusion of 14 grafts to analyze the surprising patency of certain grafts in spite of low flow. Two iliopopliteal and 12 femoropopliteal saphenous vein grafts developed pseudoocclusion 6 months to 6 years (mean 2.6 years) after the original procedure. Ten limbs presented with claudication, two with rest pain, and two with nonviable tissue. Femoral pulses were decreased in 13 limbs and distal pulses were absent in all limbs. Graft thrombosis was suspected in all cases. Occlusion proximal to the graft, either iliac (n = 11) or femoral (n = 2), was found in all 13 limbs studied angiographically. Ten limbs had one- or two-vessel runoff, and only three limbs had three-vessel runoff. Pseudoocclusions were corrected with a variety of inflow procedures, with return of pulses and resolution of symptoms in 13 limbs. One failure resulted in major amputation. We concluded that certain grafts will remain patent in spite of greatly reduced inflow and that recurrence of symptoms does not always signify graft thrombosis. Patency in spite of low flow could not be related to runoff, and autogenous vein appeared to be the graft material most tolerant of low flow.

Effects of aspirin and dipyridamole on expanded polytetrafluoroethylene graft patency

A randomized, double-blind clinical trial was designed to assess the effect of aspirin (ASA) alone or in combination with dipyridamole (DIP) on the patency rates of expanded PTFE grafts placed in the infrainguinal position. Forty-nine patients were randomized into three groups who received three times daily either two placebos (17 patients), 325 mg ASA and placebo (16 patients), or 325 mg ASA and 75 mg DIP (16 patients). The patients were seen at 3-month intervals for 1 year, and coded medication bottles were dispensed and returned pills counted to assess patient compliance. Treatment failure was defined as the first graft occlusion. The data were analyzed using the Breslow statistic for progressively censored survival type data. The 1-year cumulative patency rate for the entire series was 59%. The rates for above-knee grafts in the ASA group (100%) and the ASA/DIP group (100%) were significantly higher than the rates for the placebo group (50%) (P = 0.05). The 1-year cumulative patency rates for patients with below-knee grafts were not statistically different among the groups, although the patients who received ASA alone had a higher rate than did the other two groups (65% versus 21% for placebo and 19% for ASA/DIP). There were fewer occlusions in the above-knee grafts as compared to below-knee grafts in all groups, but the differences were statistically significant only in the ASA/DIP group. There were no statistical differences between the two active treatment groups.

Segmental thrombotic occlusion of infrarenal abdominal aorta

Five patients had segmental atherosclerotic occlusive disease confined to the midportion of the infrarenal abdominal aorta. Four of five patients had claudication, and in addition, four had evidence of peripheral microembolization and ischemic toes. Local endarterectomy or thrombectomy resulted in satisfactory restoration of distal blood flow in three patients. Two patients required replacement with a prosthetic tube graft. four of five patients have maintained good pedal pulses and have been asymptomatic for up to 14 years. These five cases were compared and contrasted with other series with similar lesions. Several causal factors are involved in segmental aortic occlusions.

Doppler evaluation of the pedal arch

The association of a patent pedal arch with early distal bypass patency has recently been emphasized. Unfortunately, in many patients information about the pedal arch can only be obtained with intraoperative angiography. An 8 mHz Doppler probe was used to noninvasively evaluate the pedal arch in 62 patients with various degrees of vascular disease. The probe was placed in the first metatarsal space, and the presence of a Doppler signal was taken as evidence of a patent pedal arch. Digital pressure was then applied over each tibial artery at the malleolar level to determine each vessel's communication with the pedal arch. Fifty-two patients were found to have patent pedal arches, while 10 did not. Preoperative hyperemic angiography or intraoperative arteriography was used to study the pedal arch in 22 of these patients. The arteriographic and Doppler findings were the same in 21 of 22 cases (96 percent accuracy). In the one case in which the results conflicted, the Doppler examination also gave information about which calf vessel contributed the most flow to the pedal arch. Preoperative Doppler evaluation of the foot combined with arteriography allows better selection of patients for distal bypass grafts.

Pediatric vascular injuries

The literature on the treatment of pediatric vascular injuries was reviewed. Aggressive treatment of arterial ischemia is clearly indicated, since children with uncorrelated arterial thrombosis are almost certain to develop a growth abnormality in the affected extremity. Alternatives to operative treatment have not been well described. Operative treatment is technically difficult and results are strongly influenced by age. To emphasize this relationship, we combined 10 cases of arterial thrombosis treated operatively in children under age 2 years complied form the literature with five similar cases reviewed retrospectively in our hospital. In these 15 patients the etiology was iatrogenic in 100%. Sixty-seven percent (10 of 15) were treated with simple thrombectomy, and only one patient (7%) received a graft. At up to 8 years of follow-up, only 26% (3 of 15) were normal, 47% (7 of 15) had thrombosis, 20% (3 of 15) had suffered tissue loss, and there had been one perioperative death. We conclude that operative treatment of an ischemic although viable limb in a small child might best be deferred if simple thrombectomy has failed or if a more complex procedure would be required at the outset, with the hope that any growth abnormality that developed could be reversed by definitive reconstruction when the child is larger.