Abnormalities of lexical and semantic processing in left temporal lobe epilepsy: an fMRI study

PURPOSE

We examined the efficiency of lexical and semantic processing and associated brain activation using functional magnetic resonance imaging (fMRI) in patients with left temporal lobe epilepsy (TLE).

METHODS

Twenty patients with left TLE (10 with hippocampal sclerosis, the HS group; and 10 with nonlesional MR scans, the NL group) and 12 healthy controls underwent an event-related fMRI analysis during a lexical decision task (LDT). Lexical and semantic processing were examined by comparing behavioral and imaging data associated with words and nonwords (lexicality) or with concrete and abstract words (concreteness).

KEY FINDINGS

Although the control group showed greater activation associated with word stimuli than with nonword stimuli in a bilateral language network, both TLE groups showed greater activation for nonword stimuli than word stimuli, including greater activation of inferior frontal language areas (bilaterally in the HS group and left-lateralized in the NL group). The TLE groups also exhibited differential activation patterns during the processing of abstract and concrete words compared to controls, and compared to each other. For abstract words, in particular, the HS group showed activation of frontal areas typically associated with executive functions, whereas the NL group showed activation of more posterior semantic processing regions.

SIGNIFICANCE

These results suggest that left TLE is associated with altered functional organization of cortical networks involved in lexical and semantic processing. In addition, the organization observed varies as a function of hippocampal pathology.

Long-term follow-up of patients with asymptomatic occlusion of the internal carotid artery with good and impaired cerebral vasomotor reactivity

BACKGROUND

Cerebral hemodynamic status might be prognostic for either the symptomatic or asymptomatic course of carotid occlusive disease. It is determined by evaluating cerebral vasomotor reactivity (VMR). We assessed VMR in asymptomatic patients with total occlusion of the internal carotid artery (ICA) and followed them to evaluate the role of impaired VMR in predicting ischaemic stroke (IS).

METHODS

Thirty-five patients (21 men, mean age ± SD 68 ± 7.5 years) with unilateral asymptomatic ICA occlusion were studied by transcranial Doppler and the Diamox test (intravenous 1.0 g acetazolamide) and followed for 48 months or until reaching the end-points of IS, transient ischaemic attack, or vascular death. VMR% was evaluated by recording the percent differences in peak systolic blood flow velocities in each middle cerebral artery at baseline and after Diamox administration.

RESULTS

Based on VMR% calculations, 14 (40%) patients had good VMRs and 21 (60%) had impaired VMRs. The global annual risk of ipsilateral ischaemic events was 5.7%. The annual ipsilateral ischaemic event risk was 1.8% in patients with good VMRs, whilst it was 7.1% in patients with impaired VMRs. An impaired VMR was significantly correlated with ipsilateral IS (Kaplan-Meier log rank statistic, P = 0.04).

CONCLUSIONS

Our results support the value of VMR assessment for identifying asymptomatic patients with carotid occlusion who belong to a high-risk subgroup for IS. New trials using extracranial-to-intracranial bypass surgery in patients with asymptomatic ICA occlusion and impaired VMRs are warranted.

A germline JAK2 SNP is associated with predisposition to the development of JAK2(V617F)-positive myeloproliferative neoplasms

Polycythemia vera, essential thrombocythemia and primary myelofibrosis are myeloproliferative neoplasms (MPN) characterized by multilineage clonal hematopoiesis. Given that the identical somatic activating mutation in the JAK2 tyrosine kinase gene (JAK2(V617F)) is observed in most individuals with polycythemia vera, essential thrombocythemia and primary myelofibrosis, there likely are additional genetic events that contribute to the pathogenesis of these phenotypically distinct disorders. Moreover, family members of individuals with MPN are at higher risk for the development of MPN, consistent with the existence of MPN predisposition loci. We hypothesized that germline variation contributes to MPN predisposition and phenotypic pleiotropy. Genome-wide analysis identified an allele in the JAK2 locus (rs10974944) that predisposes to the development of JAK2(V617F)-positive MPN, as well as three previously unknown MPN modifier loci. We found that JAK2(V617F) is preferentially acquired in cis with the predisposition allele. These data suggest that germline variation is an important contributor to MPN phenotype and predisposition.

Hyperbaric oxygen, oxidative stress, NO bioavailability and ulcer oxygenation in diabetic patients

BACKGROUND

Hyperbaric oxygen therapy (HBO2) increases tissue oxygenation, thus serving as an adjunct therapy for diabetic wounds. However, in some patients there is insufficient increase in tissue O2.

AIMS

To investigate the pathophysiology of insufficient HBO2 and the possible role of N-acetylcysteine (NAC).

METHODS

Prospective, randomized, cross-over trial included 50 diabetic patients with non-healing ulcers. Each patient received two treatments with 100% oxygen/2ATA. NAC was administered i.v. at one of the two treatments. Basal and post-treatment peri-wound transcutaneous O2 (TcPO2) pressure, malondialdehyde (MDA), total anti-oxidant status (TAOS) and nitric oxide (NO) were assessed. An ulcer oxygenation increase above 200 mmHg was accepted as sufficient.

RESULTS

During HBO2, 17 patients (34%) demonstrated insufficient increase in TcPO2. Concomitantly, their TAOS and NO decreased, while MDA increased. NAC administration attenuated these parameters, thus improving the HBO2 outcome. In those affected by NAC, the cure rate was 75%. By contrast, in 66% of patients with sufficient increase in TcPO2 TAOS was increased and MDA decreased irrespective of NAC administration. The cure rate in this subgroup was 82%.

CONCLUSIONS

Insufficient increase of ulcer oxygenation during HBO2 results from exaggerated oxidative stress and decreased NO bioavailability. NAC administration-induced modulation of both parameters and may improve ulcer oxygenation during HBO2.

Traumatic transepiphyseal separation of the upper femoral epiphysis following seizures in two children with cerebral palsy

Transepiphyseal separation of the neck of the femur following grand mal seizures is described in two children with cerebral palsy. Closed reduction and percutaneous fixation was followed by a period in a hip spica. Although the incidence of avascular necrosis of the femoral head is high following such injury, this has not occurred in these patients at a follow-up of 18 months.

Treatment of idiopathic club foot using the Ponseti method. Initial experience

We report our initial experience of using the Ponseti method for the treatment of congenital idiopathic club foot. Between November 2002 and November 2004 we treated 100 feet in 66 children by this method. The standard protocol described by Ponseti was used except that, when necessary, percutaneous tenotomy of tendo Achillis were performed under general anaesthesia in the operating theatre and not under local anaesthesia in the out-patient department. The Pirani score was used for assessment and the mean follow-up time was 18 months (6 to 30). The results were also assessed in terms of the number of casts applied, the need for tenotomy of tendo Achillis and recurrence of the deformity. Tenotomy was required in 85 of the 100 feet. There was a failure to respond to the initial regimen in four feet which then required extensive soft-tissue release. Of the 96 feet which responded to initial casting, 31 (32%) had a recurrence, 16 of which were successfully treated by repeat casting and/or tenotomy and/or transfer of the tendon of tibialis anterior. The remaining 15 required extensive soft-tissue release. Poor compliance with the foot-abduction orthoses (Denis Browne splint) was thought to be the main cause of failure in these patients.

Practice management software for the equine practitioner

Practice management software benefits the equine practitioner in many ways. Ready access to patient records, rapid entry and lookup of clinical findings, easy invoicing and monitoring of revenues, inventory management, rapid search and sorting of data, reminder and recall maintenance, and integrated word processing are just some of the software functions that assist the successful practitioner. Computer use in veterinary practice may have seemed to many to be a gimmick at one time. Now that computers have become a part of our everyday life, it is clear that they can be an essential component of the modem, successful, and profitable equine practice.

Do CT scans aid assessment of distal tibial physeal fractures?

Distal tibial physeal fractures are the second most common growth plate injury and the most common cause of growth arrest and deformity. This study assesses the accuracy of pre-operative planning for placement of the screws in these fractures using either standard radiographs or CT scans. We studied 62 consecutive physeal fractures over a period of four years. An outline of a single cut of the CT scan was used for each patient. An ideal position for the screw was determined as being perpendicular to and at the midpoint of the fracture. The difference in entry point and direction of the screw between the ideal and the observers' assessments were compared using the paired Student's t-test. There was a statistically significant improvement (p < 0.0001) in the accuracy of the point of insertion and the direction of the screw on the pre-operative plan when CT scans were used rather than plain radiographs. We would, therefore, recommend that CT scans are routinely used in the pre-operative assessment and treatment of distal tibial physeal fractures.

Congenital anomalies of the inferior vena cava revealed on CT in patients with deep vein thrombosis

OBJECTIVE

We describe a possible relationship between inferior vena cava anomalies and extensive thrombosis of the inferior vena cava and the iliac and femoral veins.

CONCLUSION

An anomaly of the inferior vena cava should be considered in young patients who present with deep vein thrombosis of the femoral and iliac veins. Coagulation abnormalities, frequently found in these patients, may be a contributory factor.

Delayed rupture of abdominal aortic false aneurysm following blunt trauma

Blunt injury of the abdominal aorta resulting in pseudoaneurysm formation is very rare. Such a pseudoaneurysm may rupture at any time, usually with fatal outcome. We report the case of a 32-year-old man with a clinically unsuspected ruptured abdominal aorta pseudoaneurysm, which had probably formed 3 years earlier, and emphasize the CT features.

Thromboembolic complications of central venous catheterization of the arm and neck veins

For more than 30 years central venous catheterization has provided an important means of long-term vascular access and circulatory monitoring. Thrombosis of central veins is one of the serious complications of this procedure, The reported incidence of thrombosis varies and it is often underestimated clinicaIly due to the pau city of signs and symptoms. Symptomatic subelavian vein thrombosis is estimated to occur in up to 15% of patients with indwelling venous access devices.

Ontogenetic development of energy-supplying enzymes in rat and guinea-pig heart

The purpose of the present study was to compare the ontogenetic development of the activity of myocardial energy-supplying enzymes in two mammalian species, differing significantly in their level of maturation at birth. The animals were investigated during the late prenatal period and 2, 7, 14, 21, 25, 30, 63, 120 and 730 days after birth in the rat and 2, 21, 84 and 175 days in the guinea-pig. The following enzymes were assayed in the right and left ventricular myocardium: lactate dehydrogenase (LDH, lactate uptake and/or formation), triose phosphate dehydrogenase (TPDH, carbohydrate metabolism), glycerol phosphate dehydrogenase (GPDH, glycerol-P shuttle)), hexokinase (HK, glucose phosphorylation), malate dehydrogenase (MDH, tricarboxylic cycle), citrate synthase (CS, tricarboxylic cycle) and hydroxyacyl-CoA dehydrogenase (HOADH, fatty acid breakdown). The rat heart, highly immature at birth, exhibits three different developmental patterns of energy-supplying enzymes, identical in both ventricles: (i) two mitochondrial enzymes of aerobic metabolism (CS, HOADH) and GPDH have a relatively low activity at the end of prenatal life; thereafter their activity steadily increases, approaching the adult levels between the 3rd and 4th postnatal weeks. A significant decrease was observed between the 4th and 24th months. (ii) MDH and LDH: prenatal values were significantly higher as compared with the 2nd postnatal day; after this period the activities increased up to adulthood (4 months) and decreased during senescence. (iii) The activities of HK and TPDH are characterized by only moderate changes during development. HK differs from all other enzymes by the highest prenatal values, which exceed even adult values. In contradiction to the rat heart, the developmental differences in more mature guinea-pig heart were significantly less pronounced. The only ontogenetic differences observed were the lower activities of enzymes connected with aerobic metabolism at the end of the prenatal period. Our results point to possible differences in the development of adaptive metabolic pathways in animals with different levels of maturation at birth.

Treatment of postcatheterisation false aneurysms: ultrasound-guided compression vs ultrasound-guided thrombin injection

OBJECTIVES

to compare the efficacy and cost-effectiveness of ultrasound-guided compression (UGC) with ultrasound-guided thrombin injection (UGTI) for treatment of postcatheterisation arterial false aneurysms (cFA).

DESIGN

prospective clinical study using historical controls.

MATERIALS AND METHODS

we prospectively collected data on 33 consecutive patients diagnosed with cFA larger than 1.5 cm in diameter. These were treated with UGTI. We performed a retrospective review of data on a former group of 33 consecutive historical control patients that were treated by UGC.

RESULTS

the groups were similar in respect of demographic and clinical variables. Thirty patients were suitable for UGC and 33 patients were suitable for UGTI. The success rate for UGC was 26/30 (87%) compared to 33/33 (100%) for UGTI (p<0.05). Thrombosis was achieved during the first treatment session in 7/26 patients treated by UGC, compared to 26/33 in the UGTI group (p<0.0001). Four patients that failed UGC and two patients that were unsuitable for UGC required surgical repair. UGTI as compared to UGC was shorter in duration (25 vs 75 min) and required no sedation. No thromboembolic or systemic complications occurred in either group. Cost analysis revealed savings of $US 517 for each patient treated by UGTI as compared with UGC.

CONCLUSIONS

in our study, UGTI is superior to UGC, and we suggest that UGTI should become the procedure of choice for the treatment of cFA.

Epidemiology and control of diphtheria in the Republic of Moldova, 1946-1996

In 1994-1996, the Republic of Moldova was stricken with an epidemic of diphtheria after >30 years of routine diphtheria immunization and the near absence of the disease for nearly 20 years. The intensity of the epidemic gradually grew, reaching a peak in 1994-1995. The epidemiology of diphtheria in Moldova during this period is described along with laboratory findings and control measures. Pharyngeal diphtheria was the predominant clinical form of the disease (97% of cases), and it most often developed in a localized form (70%), with 20% in the toxic form. The clinical diagnosis of diphtheria was bacteriologically confirmed in 91% of cases: Of the cases tested for biotype, 91.3% were gravis, 8.5% were mitis, and 0. 2% were intermedius. Of 494 toxigenic isolates from cases and carriers at the beginning of the epidemic, 47% were nonphagotypeable strains, and 25.7% were phagotype VI strains. Aggressive population-based diphtheria control measures, a mass immunization campaign, rapid case identification, antibiotic prophylaxis and supplemental immunization of close contacts in clusters of infection, and high coverage with routine immunization rapidly controlled the epidemic within Moldova.

Strategies for safe injections

In 1998, faced with growing international concern, WHO set out an approach for achieving injection safety that encompassed all elements from patients' expectations and doctors' prescribing habits to waste disposal. This article follows that lead and describes the implications of the approach for two injection technologies: sterilizable and disposable. It argues that focusing on any single technology diverts attention from the more fundamental need for health services to develop their own comprehensive strategies for safe injections. National health authorities will only be able to ensure that injections are administered safely if they take an approach that encompasses the whole system, and choose injection technologies that fit their circumstances.

The problem of "concreteness"

"Concrete" patients manifest resistance to interpretation per se. Their apparently primitive thinking is the result of complex psychodynamics, explicable in terms of the mechanisms of wish fulfillment and a revised theory of fetishism. The general thesis is that an unconscious equation of differentiation with overwhelming tension leads to a global process of defense against the differentiating function of the analytic frame. The wider implications of this theory can be integrated with Freud's mostly unknown late attempt to generalize the theory of fetishism.

Transiently increased basilar artery flow velocity following severe head injury: a time course transcranial Doppler study

BACKGROUND AND PURPOSE

Transcranial Doppler ultrasonography has been used to study changes in cerebral hemodynamics following head injury. However, most studies evaluated the anterior circulation and little information exists on transcranial Doppler of the vertebrobasilar arteries after head injury.

METHODS

Thirty-two patients with a Glasgow Coma Scale (GCS) score between 4-8 and 11 patients with a GCS score between 9-14 were studied using transcranial Doppler ultrasonography for the first 10 days after injury. Daily variations in the mean blood flow velocities of all major cerebral arteries were recorded.

RESULTS

In patients with GCS score between 4-8, the mean blood flow velocities in the middle cerebral and basilar arteries gradually increased beginning on day 2 postinjury and peaked on the 4th-5th day after injury. Those changes were more prominent, and appeared earlier, in the basilar artery. The ratio between the mean flow velocities of the middle cerebral artery and the basilar artery during the first 4 days was significantly lower than in normal controls, indicating a particular increase of flow velocity in the basilar artery. Nineteen out of 32 patients (60%) with severe head injury showed mean blood flow velocity increased over 75 cm/sec in the basilar artery. Mean blood flow velocity >90 cm/sec in the basilar artery, compatible with vasospasm, was observed in 12 of 32 patients (37%). Spasm in the middle cerebral artery was observed in 12 (37%) of patients; 10 of them also had evidence of basilar artery spasm. On the whole, 14 of 32 (43%) patients had evidence of spasm either in the middle cerebral or basilar arteries or in both. In 5 of 11 patients (50%) with moderate head injury (GCS score 9-14), blood flow velocity in the basilar artery greater than 75 cm/sec was observed, but in only two of them it reached the values over 90 cm/sec. Vasospasm in the middle cerebral artery was noted in one patient.

CONCLUSIONS

A significant number of patients develop increased flow velocities compatible with vasospasm in the basilar artery after severe head injury. This phenomenon may represent an additional factor that contributes to the poor outcome of severely head-injured patients.

Lateral venous ulcer and short saphenous vein insufficiency

PURPOSE

The objective of this report is to emphasize the importance of saphenopopliteal junction (SPJ) reflux in the genesis of lateral leg ulcers and to suggest a proper diagnostic and therapeutic approach.

METHODS

Twenty legs with isolated lateral perimalleolar ulcers from the basis for this report. None had medial ankle ulcers, and most showed no hyperpigmentation or lipodermatosclerosis. Fifteen had been treated with a nonvenous diagnosis. Reflux at the SPJ was detected by handheld continuous wave Doppler and was confirmed with duplex scans. No other abnormalities were found. Brief conservative treatment and duplex localization of the SPJ preceded its ligation and division.

RESULTS

All ulcers healed within 12 weeks, but one in a radiated leg recurred at 9 months. Other complications included two hematomas and one each of ankle edema, superficial wound infection, and sural neuropathy.

CONCLUSIONS

Even isolated lateral leg and ankle ulcers with minimal accessory venous stigmata can be of venous reflux origin. Detection with the continuous wave Doppler and confirmation of reflux and localization of the SPJ allow surgical correction to proceed swiftly with an expectation of satisfactory results.

Closure of the abdomen by mesh for planned re-laparotomy. A technical modification

Temporary closure of the abdomen with a synthetic mesh and multiple planned relaparotomies are the essentials of the modern strategy for treating severe intra-abdominal sepsis or pancreatic necrosis. One of the complications associated with mesh closure of the abdomen is facial necrosis at the wound edges leading to evisceration. Tension of the strictures between mesh and facia called local ischemia, which combined with infection leads to the facial disintegration and separation of the mesh from the abdominal wall. A modified technique of suturing the mesh was developed in our department and its technical details are presented. Twenty-four patients treated with the "open abdominal technique and planned relaparotomies" are presented. The new technique was used in 9 patients for closure of evisceration after mesh separation.

Vascular complications of total abdominal perfusion and aortic stop-flow infusion

During a 2 year period (1992-1993), 149 patients with advanced abdominal cancer underwent total abdominal ischemic perfusion (TAP) and stop-flow infusion (SFI) 159 times in an attempt to achieve palliation. These procedures and aortic stop-flow infusion require insertion of balloon catheters into the abdominal aorta and inferior vena cava by a transfemoral approach. Flow is arrested for 15 minutes, during which time chemotherapeutic agents are infused into the aorta, distal to the balloon occlusion. Femoral access is by a surgical incision. The passage of the catheters is guided by fluoroscopy. Some tumor response was observed in 35% of the patients. Ten patients had major vascular complications; two iliac artery aneurysms were lacerated and required emergency repair. There were two femoral artery false aneurysms that required surgical correction, one early and one late. Aortic dissection was detected in four patients, but these did not require surgical intervention. Two patients had thrombosis distal to the occluded vessel, both required surgical intervention. To reduce the incidence of these vascular complications we recommend: (1) a clinical and vascular laboratory evaluation before the procedure, and (2) angiography of normal flow in patients with underlying vascular disease.

Two cases of acetabular fractures sustained during competitive cycling

This paper reports two cases of posterior acetabular fracture obtained in an almost identical way in competitive cycling and presents potential diagnostic difficulties.

A software toolkit for hierarchical task analysis

This paper describes a prototype software tool that offers support to the human factors specialist using hierarchical task analysis (HTA). The tool provides a direct manipulation diagram editor for HTA and provides high-quality output of analyses, in both graphic and automatically generated tabular form. The tool is implemented in Smalltalk-80 and currently runs on Macintosh computers.

Aspects of urethrality in women

It has long been noticed that women experience direct sexual stimulation from urethral practices that men do not. However, this empirical finding remains to be integrated with the general theory of female psychosexual development. An attempt is made to begin such an integration, with a focus on urethral perversions or perverse trends.

Exteriorized chronic aorto-caval arteriovenous access shunts in the baboon (Papio cynocephalus)

A chronic arteriovenous (AV) blood access shunt has been developed in baboons. It is composed of silicone rubber tubing extensions bonded to vascular graft polytetrafluoroethylene (ePTFE) cuffs, for creating anastomoses with the distal aorta and inferior vena cava. Following surgical implantation, shunts remain patent for months (X = 9 +/- 2.5 months) and provides long-term ex vivo access to non-anticoagulated blood (Mean Blood Flow = 312 +/- 69 mL/min).

Interruption of vascular thrombus formation and vascular lesion formation by dietary n-3 fatty acids in fish oil in nonhuman primates

BACKGROUND

Because of discrepant claims regarding the relative biological effects of n-3 fatty acids (n-3FAs), we have concurrently measured the effects of dietary n-3FAs on blood and vascular lipid composition, hemostatic function, blood thrombotic responses, vascular thrombus formation, and vascular lesion formation in baboons.

METHODS AND RESULTS

Dietary n-3FAs displaced n-6FAs in plasma, platelets, blood vessels, and corresponding urinary eicosanoid metabolites (p < 0.01 in all cases) within weeks after initiation of a semipurified diet containing 1 g/kg per day n-3FA-ethyl ester concentrate (composed of two thirds eicosapentanoic acid and one third docosahexanoic acid). Coincidentally, platelet hemostatic function became minimally impaired (template bleeding times prolonged from 4.3 +/- 0.5 minutes to 7.6 +/- 1.3 minutes, p = 0.039); concentrations of collagen producing half-maximal platelet aggregation increased (from 6.4 +/- 2.1 to 8.5 +/- 2.5 micrograms/mL, p = 0.045); and tissue factor expression by endotoxin-stimulated blood monocytes fell (from 6.5 +/- 1.2 to 1.7 +/- 0.14 mU/10(6) cells, p < 0.005). Dietary n-3FAs decreased deposition of platelets onto thrombogenic segments of Dacron vascular graft incorporated into chronic exteriorized femoral arteriovenous (AV) shunts, a thrombotic process resistant to the effects of both aspirin and heparin (111In-labeled platelet deposition decreased from 14.1 +/- 1.4 x 10(9) platelets/5-cm segment at 40-60 minutes with occlusion to 7.5 +/- 0.8 x 10(9) platelets/5-cm segment without occlusion; p < 0.001). Platelet deposition onto segments of endarterectomized homologous normal aorta in the AV shunts of n-3FA-treated animals was similarly reduced (from 4.4 +/- 0.9 to 1.8 +/- 0.4 x 10(9) platelets; p < 0.01). Dietary n-3FAs interrupted vascular thrombus formation at sites of surgical carotid endarterectomy (platelet deposition, 1.5 +/- 0.4 versus 4.4 +/- 1.0 x 10(9) platelets in untreated controls; p < 0.001). Moreover, endarterectomized aortic segments (EASs) from n-3FA-treated donors exhibited little capacity to induce thrombus formation when tested in the AV shunts of control recipient animals (0.24 +/- 0.10 versus 4.4 +/- 0.90 x 10(9) platelets). However, in the converse crossover experiments, EASs from control animals actively accumulated platelets when studied in the AV shunts of n-3FA-treated animals (1.8 +/- 0.4 x 10(9) platelets; p < 0.01 versus n-3FA-treated EASs in shunts of normal animals). Dietary n-3FAs also abolished vascular lesion formation at sites of carotid endarterectomy 6 weeks after surgery (cross-sectional area of neointima 0.048 +/- 0.031 mm2 compared with 0.428 +/- 0.104 mm2 in control arteries; p = 0.010).

CONCLUSIONS

In nonhuman primates, dietary n-3FAs in high doses eliminate both vascular thrombus formation and vascular lesion formation after mechanical vascular injury while largely sparing hemostatic function and modestly reducing blood thrombotic responses. These effects are attributed to selective n-3FA-dependent alterations in cellular membrane functions.

Interruption of vascular thrombosis by bolus anti-platelet glycoprotein IIb/IIIa monoclonal antibodies in baboons

PURPOSE

Because the platelet membrane receptor glycoprotein IIb/IIIa plays a central role in the recruitment of platelets into forming thrombus, therapeutic inhibition of this receptor complex may be particularly useful to prevent thrombosis after small vessel arterial manipulation.

METHODS

The relative hemostatic safety and antithrombotic efficacy for thrombus formation at sites of endarterectomy and implanted prosthetic vascular graft of a murine monoclonal antibody (LJ-CP8) against platelet glycoprotein IIb/IIIa have been determined in baboons after bolus injections in doses (10 mg/kg) that block platelet receptor function for fibrinogen and other adhesive glycoproteins (absent platelet aggregation and bleeding times > 30 minutes without affecting circulating platelet counts).

RESULTS

Thrombus formation was eliminated by LJ-CP8 at sites of surgical endarterectomy in fresh segments of homologous aorta incorporated into chronic exteriorized arteriovenous femoral shunts (accumulation of indium 111-labeled platelets fell from 4.40 +/- 0.89 x 10(9) platelets/cm in control animals [n = 6] to 0.23 +/- 0.01 x 10(9) platelets/cm in treated animals [n = 4]; p < 0.005). The formation of thrombus was also abolished by LJ-CP8 at sites of 1 cm prosthetic vascular grafts (4 mm inner diameter polytetrafluoroethylene grafts) interposed into common carotid arteries (deposition of indium 111-labeled platelets decreased from 2.57 +/- 0.43 x 10(9) platelets/cm [n = 5] to 0.16 +/- 0.06 x 10(9) platelets/cm, [n = 4]; p = 0.004). However, LJ-CP8 injections produced substantial bleeding in the surgical wound during the first few hours after operation. Thirty days after operation all four graft implants were patent in JJ-CP8-treated animals compared with two of five in control animals (p = 0.06).

CONCLUSIONS

We conclude that profound inhibition of platelet glycoprotein IIb/IIIa receptor function by single bolus injection of LJ-CP8 monoclonal antibody transiently abolishes platelet hemostatic function, eliminates acute thrombus formation at sites of endarterectomy and prosthetic vascular graft implants, and may improve vascular patency.

Percutaneous transluminal aortic angioplasty: early and late results

Percutaneous transluminal angioplasty of the infrarenal abdominal aorta (13 patients) and its bifurcation (15 patients) was performed in 28 patients with a total of 32 dilatation procedures. The group consisted of 16 female and 12 male patients and initial successful dilatation was achieved in all. Recurrence within 1 month requiring bypass surgery occurred in 1 patient. Three patients were lost to follow-up. Long-term follow-up in the remaining 24 patients ranged from 1 to 9 years with a mean of 4.5 years. During the follow-up period, repeat angioplasty of the original stenosis was performed in 3 patients and another patient underwent dilatation of a new lesion which developed in the aorta. According to clinical and noninvasive studies, these 4 patients, as well as the other 20, have maintained patency of the treated lesions and are symptom free. No immediate complications requiring surgery occurred. We conclude that angioplasty is the initial treatment of choice in focal lesions of the distal abdominal aorta and its bifurcation.

Laser Doppler flowmetry in lower extremity ischemia: application and interpretation

The present study was undertaken in order to develop numerical criteria for the parameters of laser Doppler flowmetry-skin blood flow velocity and pulse wave amplitude in the evaluation of lower extremity ischemia. Fifty limbs of young healthy volunteers were examined in order to obtain baseline normal values. Patient population was divided into moderately ischemic (52 limbs) and severely ischemic (22 limbs), based on patients' complaints, physical examination, ankle-brachial indices, pulse volume recordings and arteriographies. Univariate comparison between the three groups of skin blood flow velocity and pulse wave amplitude at each time point were done by analysis of variance. Power of discrimination between degrees of ischemia was evaluated by computing sensitivity and specificity, based on skin blood flow velocity and pulse wave amplitude values at time points best for predicting the severity of disease by multiple regression analysis. Using cutoff points of < 31 for skin blood flow velocity and < 9 for pulse wave amplitude, a 96% sensitivity and 96% specificity were obtained in separating normal from ischemic limbs. Cutoff points of < 9 for skin blood flow velocity and < 4 for pulse wave amplitude discriminated with a 100% sensitivity and specificity between the moderately and severely ischemic limbs. We propose the use of laser Doppler flowmetry with local heating and reactive hyperemia, and the cutoff points stated above as an additional tool to evaluate lower extremity ischemia through assessment of cutaneous microcirculation.

Antihemostatic and antithrombotic effects of monoclonal antibodies against von Willebrand factor in nonhuman primates

BACKGROUND

Because the adhesive glycoprotein von Willebrand Factor (vWF) mediates initial platelet attachment at sites of vascular injury and may also contribute to shear-dependent platelet thrombus formation, we have determined in vivo the relative antithrombotic efficacy and hemostatic safety of infusing murine monoclonal antibodies against vWF.

METHODS

In baboons with chronic arteriovenous shunts, thrombus formation was initiated by interposition of thrombogenic Dacron vascular grafts (VG) and endarterectomized baboon aortic segments (EAS). Thrombus formation on VG and EAS was assessed by use of real-time scintillation camera imaging of indium 111-labeled platelet deposition. In control and treated animals (anti-vWF antibody) platelet hemostatic competence was evaluated by means of serial measurements of platelet count, bleeding time, and ex vivo platelet aggregation in response to adenosine diphosphate and ristocetin.

RESULTS

Although bolus antibody infusions did not affect circulating platelet counts, bleeding times were immediately prolonged to 28 +/- 4 minutes (vs 4.7 +/- 0.4 minutes before treatment, p = 0.01). Bleeding times normalized within 24 hours after antibody administration. Platelet aggregation in response to adenosine diphosphate was unchanged by antibody therapy, whereas ristocetin-induced platelet aggregation was abolished acutely and remained impaired for 24 hours. Platelet deposition on VG after 60 minutes of exposure to flowing blood was 2.95 +/- 0.74 x 10(9) platelets/cm in six control animals as compared to 1.86 +/- 0.16 x 10(9) platelets/cm in five treated animals (p = 0.04). Similarly, platelet deposition on EAS averaged 4.40 +/- 0.89 x 10(9) platelets/cm in control studies and was reduced significantly by antibody therapy (1.52 +/- 0.50 x 10(9) platelets/cm, p = 0.02).

CONCLUSIONS

Despite profound interruption of platelet hemostatic functions, therapeutic targeting of vWF modestly inhibits platelet-dependent thrombosis.

Autoimmune mechanisms in thromboangiitis obliterans (Buerger's disease): the role of tobacco antigen and the major histocompatibility complex

This study is a continuation of our previous work that showed that patients with thromboangiitis obliterans (TAO; Buerger's disease) demonstrate a cell-mediated immune response to human artery type-specific collagens. To investigate the role of cigarette smoking in patients with TAO, cellular and humoral sensitivity was tested to a tobacco glycoprotein (TGP) antigen in 13 patients with Buerger's disease, 16 healthy smokers, and 12 nonsmoking healthy young male subjects. In this study, patients with Buerger's disease and healthy smokers had the same rate of cellular response to TGP, whereas nonsmokers did not respond. All three groups had a 30% to 40% measurable antibody response to TGP. If TGP has an immunologic role in the pathogenesis of TAO, an additional factor (or factors) may be operative. A specific genetic makeup may be one such factor, although at this stage other pathogenic mechanisms cannot be ruled out. Eleven patients with Buerger's disease and two control groups of 10 young healthy smoking male subjects and 12 young nonsmokers underwent histocompatibility leukocyte antigen (HLA) typing. Patients with Buerger's disease had a statistically significantly higher frequency of HLA-DR4 and a significantly lower frequency of the HLA-DRW6 antigen than had both control groups. Because similar findings have been reported in other autoimmune diseases, this observation may serve as further evidence that an autoimmune mechanism is involved in Buerger's disease.

Dimorphic male brains and alternative reproductive tactics in a vocalizing fish

Brains and types of behavior among sexually mature vertebrates are portrayed as having two phenotypic states: male and female. However, mating systems and the behavioral tactics employed by the two sexes are far more diverse than conveyed by this simple intersexual dichotomy. For example, in many species, sexually mature males may practice one of two alternative mating tactics. Recent studies of a sound-producing teleost fish now show that intrasexual dimorphism of vocal motor phenotypes among males accompanies the intrasexual divergence of types of reproductive behavior. Thus, one group of males, like females and juveniles, lacks the behavioral, neurophysiological and morphological traits typical of the sexually differentiated vocal motor pathway of the second group. The results are an explicit demonstration that for any one species: (1) alternative mating tactics can be paralleled by alternative phenotypes for the neurons that determine tactic-specific types of behavior, and (2) reproductive maturation is not obligatorily linked to the expression of neuronal secondary sex characteristics.