RASA1: variable phenotype with capillary and arteriovenous malformations

Capillary malformation-arteriovenous malformation (CM-AVM) is a newly discovered hereditary disorder. Its defining features are atypical cutaneous multifocal capillary malformations often in association with high-flow lesions: cutaneous, subcutaneous, intramuscular, intraosseous and cerebral arteriovenous malformations and arteriovenous fistulas. Some patients have Parkes Weber syndrome - a large congenital cutaneous vascular stain in an extremity, with bony and soft tissue hypertrophy and microscopic arteriovenous shunting. In the past, arteriovenous malformations and arteriovenous fistulas had been considered non-hereditary. A classical genetic approach was used to identify the locus. Candidate gene screening pinpointed mutations in RASA1 (p120-RASGAP) - a RasGTPase. RASA1 reverts active GTP-bound Ras into inactive GDP-bound form. Murine Rasa1 knockout and tetraploid-aggregated embryos with RNA interference exhibited abnormal vascular development. Lack of RASA1 activity caused inhibition of cell motility, possibly through p190-RhoGAP. Thus, RASA1 defects probably cause abnormal angiogenic remodeling of the primary capillary plexus that cannot be compensated for by other RasGAPs: RASA2, RASAL and NF1. Signaling pathways involving RASA1 might offer novel targets for treatment of high-flow vascular anomalies.     

Skeletal changes associated with vascular malformations

Five hundred and eighty birthmarks were reviewed; 356 were hemangiomas and 224 were malformations. Bony alterations occurred in association with only 1 percent of hemangiomas, in contrast with 34 percent of patients with vascular malformations. These alterations in bone development were classified according to size, shape, and density changes. Hypertrophy and distortion were typical of lymphatic malformations. Hypoplasia and demineralization were characteristic findings in the extremity venous malformations. Destructive and intraosseous changes were more commonly noted in the arterial or high-flow lesions. Possible mechanisms of altered skeletal growth include mechanical, physiological, and developmental processes.     

Use of magnetic resonance imaging for the evaluation of vascular malformations of the lower extremity

Vascular malformations are anatomically subdivided according to the predominant channel anomaly into either capillary, arterial, venous, lymphatic, or combinations. They can be further subdivided into high- or low-flow malformations. Any lesion that has an arterial component is considered a high-flow malformation. Once the diagnosis of a vascular malformation is made, it is of paramount importance to define not only the flow characteristics but also the full range of extension, because the prognosis and appropriate treatment vary substantially for each type of anomaly. The two most useful noninvasive imaging techniques for assessing vascular malformations are magnetic resonance imaging (MRI) and ultrasonography. The aim of this review is to give surgeons involved in treating patients with vascular malformations an opportunity to gain some background on MRI scans when assessing vascular malformations. Although MRI is a powerful modality for assessing vascular malformations, we will also discuss some of the limitations of MRI. We further suggest a diagnostic flow chart developed on the basis of MRI features designed to help determine the composition of a vascular birthmark when intervention is anticipated.     

The role of magnetic resonance imaging in the management of vascular malformations of the trunk and extremities

Vascular malformations can usually be diagnosed on clinical grounds. They have a well-defined appearance on magnetic resonance imaging, which can effectively determine their tissue and flow characteristics. However, the role of cross-sectional imaging in the management of vascular malformations is not well defined. Most reviews suggest that magnetic resonance imaging should be reserved for cases in which the extent of the lesion cannot be estimated on physical examination. However, to date no group has compared the accuracy of physical examination alone to that of magnetic resonance imaging in determining this extent. A review was performed of all the patients evaluated for vascular malformations at the New York University Trunk and Extremity Vascular Anomalies Conference between July of 1994 and August of 1999. Patients who underwent magnetic resonance evaluation at other institutions and whose images were not available for review were excluded. All study patients either underwent magnetic resonance imaging examination at New York University Medical Center or had outside films reviewed at the center. The physical examination findings were compared with the magnetic resonance findings and the surgeon and radiologist made a joint decision about whether there was a correlation between the magnetic resonance and physical examination findings. Fifty-eight patients met the study criteria, 44 (76 percent) of whom were found to have more extensive disease on magnetic resonance examination than appreciated on physical examination. Of the 51 patients with low-flow vascular malformations (venous vascular malformations, lymphatic malformations, and capillary malformations), 39 (76 percent) had more extensive disease on magnetic resonance examination than on physical examination. Of the seven patients with high-flow arteriovenous malformations, five had more extensive disease on magnetic resonance. In all of the 44 patients whose magnetic resonance imaging findings did not correlate with those of the physical examination, therapeutic decision making was affected. Contrary to the conventional wisdom of published reviews, physical examination findings significantly underestimated the extent of vascular malformations in the majority of cases. Magnetic resonance imaging should be performed in all patients with vascular malformations of the trunk and extremities before therapy is planned. In an age when physicians are asked to justify their decisions, especially where the use of expensive diagnostic modalities is concerned, the situations in which these tests are indispensable must be clearly defined or else patients will be denied access to them.     

Venous malformations of skeletal muscle

Intramuscular venous malformations are often mistaken for tumors because of a similar presentation and improper nomenclature. This is a review of 176 patients with venous malformations localized to skeletal muscle compiled from the Vascular Anomalies Center at Children's Hospital from 1980 through 1999. The female-to-male ratio was 2:1. Two-thirds of skeletal muscle venous malformations were noted at birth; the remainder manifested in childhood and adolescence. Venous malformations occurred in every muscle group, most often in the head and neck and extremities. Pain and swelling were the usual presenting complaints. Skeletal problems, such as fracture, deformation, or growth abnormalities, were rare. Hormonal exacerbation and intralesional bleeding were infrequent. Magnetic resonance imaging showed the lesions to be isointense to surrounding muscle on T1-weighted sequences and hyperintense on T2-weighted images. Characteristic tubular or serpentine components were oriented along the muscular long axis. Thrombi were hyperintense on T1-weighted and hypointense on T2-weighted sequences; phleboliths were seen as signal voids on all sequences. Gross examination of resected specimens revealed multicolored tissue with dilated vascular channels, frequently containing phleboliths. Light microscopy showed aggregates of primarily medium-sized, thin-walled vascular channels with flat endothelium and variable smooth muscle, most closely resembling dysplastic veins. Three lesions had a different histologic appearance consisting predominantly of small vessels with capillary structure and proliferative activity admixed with large feeding and draining vessels, similar to a lesion called intramuscular capillary hemangioma in the literature. The endothelium in these three lesions was negative for glucose transporter-1 by immunostaining. Eight percent of the patients, who had minor or no symptoms, were not treated. Twenty-four percent of the patients were managed conservatively (with aspirin and compressive garments); for 17 of these patients (10 percent of 176), noninvasive therapy was not successful, and they proceeded to sclerotherapy, excision, or both. A total of 31 percent of the patients had sclerotherapy, 20 percent had excision, and 27 percent had combined sclerotherapy and excision. Sclerotherapy was used for diffuse lesions, except for those with multiple intralesional thromboses, neurologic impairment, or compressive signs and symptoms. Resection was preferred for venous malformations well localized to a single muscle or muscle group, particularly if the muscles are expendable. Therapeutic outcomes were recorded in the charts or obtained by telephone interview in 122 of the patients (69 percent). Of these, compression garment and aspirin, resection, sclerotherapy, or combined excision and sclerotherapy improved symptoms in 121 patients (92 percent); no change was noted in 10 patients (8 percent). Only one patient was worse (self-reported) after intervention.     

Autoantibody to MOG suggests two distinct clinical subtypes of NMOSD

We characterized a unique group of patients with neuromyelitis optica spectrum disorder(NMOSD) who carried autoantibodies of aquaporin-4(AQP4) and myelin-oligodendrocyte glycoprotein(MOG). Among the 125 NMOSD patients, 10(8.0%) were AQP4- and MOG-ab double positive, and 14(11.2%) were MOG-ab single positive. The double-positive patients had a multiphase disease course with a high annual relapse rate(P=0.0431), and severe residual disability(P0.0001). Of the double-positive patients, 70% had MS-like brain lesions, more severe edematous, multifocal regions on spinal magnetic resonance imaging(MRI), pronounced decreases of retinal nerve fiber layer thickness and atrophy of optic nerves. In contrast, patients with only MOG-ab had a higher ratio of monophasic disease course and mild residual disability. Spinal cord MRI illustrated multifocal cord lesions with mild edema, and brain MRIs showed more lesions around lateral ventricles. NMOSD patients carrying both autoantibodies to AQP4 and MOG existed and exhibited combined features of prototypic NMO and relapsing-remitting form of MS, whereas NMOSD with antibodies to MOG only exhibited an "intermediate" phenotype between NMOSD and MS. Our study suggests that antibodies against MOG might be pathogenic in NMOSD patients and that determination of anti-MOG antibodies maybe instructive for management of NMOSD patients.     

Compartmentalization of massive vascular malformations

A total of 18 patients with massive vascular malformations of the head and neck region were treated with compartmentalization using nonabsorbable sutures followed by injection of a sclerosant agent into each compartment. The indication for compartmentalization was either to stop potentially uncontrollable, life-threatening hemorrhage during the dissection of the lesion or to reduce its vascularity to allow a less dangerous subsequent resection. Compartmentalization was used in both high-flow and low-flow vascular malformations. In this technique, large nonabsorbable sutures are placed deeply in multiple areas within the lesion. The aim is to divide the malformation into multiple compartments by changing the direction of the suturing; in this way the sclerosing agent is provided with a more effective environment. The sclerosant used was either sodium tetradecyl sulfate 3%, absolute alcohol, or both. The total amount of infiltrate varied from 3 to 35 cc, according to the size of malformation. After compartmentalization, swelling was the most noticeable complication. With this technique, it was possible to treat what were considered untreatable malformations using standard techniques and to control the inevitable serious bleeding.     

Changes in Muscle Volume and Composition After Treatment of Hip Dysplasia with Periacetabular Osteotomy

BackgroundPeriacetabular osteotomy (PAO) is a common treatment for pre-arthritic hip dysplasia in young adults. The purpose of this study was to better understand changes in muscle volume and composition after PAO visualized using magnetic resonance imaging (MRI).MethodsA prospectively collected series of individuals that underwent PAO for hip dysplasia were reviewed to identify subjects with pre- and postoperative MRI. In our practice, MRI was obtained preoperatively and greater than 6 months after PAO for persistent hip pain. MRI sequences were selected to optimize visualization of the muscle volume, fatty infiltration, and hip joint cartilage. MRI images were selected at predetermined bony landmarks and analyzed using 3D Slicer (©2021, www.slicer.org) software to measure muscle diameter and calculate muscle cross-sectional area (CSA) in 17 individual muscles surrounding the hip. Muscle atrophy was graded using the Goutallier classification for fatty infiltration and acetabular cartilage condition was graded using the Outerbridge classification. We compared pre- and postoperative muscle area and composition as well as cartilage for each case.ResultsA series of six female patients met our inclusion criteria. Mean age was 26 years at time of surgery. All cases had MRI sequences adequate for muscle volume measurements. Fatty infiltration and cartilage changes were recorded in four subjects with appropriate MRI sequences. Separating muscle groups, external rotators underwent the largest volume increase. Hip flexors demonstrated mild volume decrease. CSA change among external rotators averaged +12%, hip flexors -9.3%, and hip abductors -9.2% after PAO. All muscles had either the same or increased fatty infiltration after surgery, with gluteus medius and iliacus undergoing the most average increase. Similarly, cartilage condition worsened by a small margin in this series.ConclusionOur results provide preliminary indication that PAO may have noticeable effects on muscle characteristics and cartilage in the early postoperative period. This was a limited case series of subjects with adequate pre- and post-operative MRI imaging.Level of Evidence: IV     

Distinguishing soft-tissue hemangiomas from vascular malformations using technetium-labeled red blood cell scintigraphy.

Soft-tissue vascular lesions in children can be classified as either hemangiomas or vascular malformations. The distinction between the two has important prognostic and therapeutic implications. Over the past 8 years, we have evaluated 64 vascular lesions with the technetium-labeled red blood cell (Tc-RBC) scan. Twenty-eight lesions imaged as hemangiomas with intense focal uniform uptake. This diagnosis was confirmed in 27 lesions, or 96 percent. Thirty-six lesions imaged as vascular malformations with abnormal vessels or diffusely increased activity. This diagnosis was confirmed in 35 lesions, or 97 percent. Overall, the Tc-RBC scan was 97 percent accurate in distinguishing hemangiomas from vascular malformations. It is particularly useful when the clinical diagnosis of the lesion may not be evident. Not only can biopsy be avoided, but parents can be reassured at an earlier age and given accurate information regarding prognosis.     

Histologic change of arteriovenous malformations of the face and scalp after free flap transfer

In three patients with long-standing vascular malformations of the face and scalp, radial forearm free flaps were transferred after a near-total excision of the lesion. All patients had typical high-flow malformations with thrill and bruit. The onset and progression of the malformations were analyzed through clinical and histologic studies. After free flap transfer, the vascular malformations were followed up grossly and histologically for between 4 and 9 years. There was no recurrence of arteriovenous malformation after free flap transfer. The portion of the residual lesion adjacent to the transferred free flap disappeared, and the remaining discoloration also vanished grossly. Histologic comparison of immediate postoperative and 4-month postoperative specimens from the margin and residual lesion using Victoria blue staining showed that the typical preoperative findings for arteriovenous malformation-an intermingling of thick-walled vessels with abundant elastic fibers and thin-walled vessels without elastic fibers-had undergone change, resulting in the disappearance of the thick-walled vessels and leaving only homogeneous, thin-walled vasculature. The highly vascularized free flap, which does not contain abnormal fistulas, impacted the histologic change of the arteriovenous malformation by blocking the vicious cycle of ischemia and anatomic replacement of disfigured skin and subcutaneous tissues.     

Chiari malformation, cervical spine anomalies, and neurologic deficits in velocardiofacial syndrome

The purpose of this investigation was to evaluate the prevalence of Chiari malformation, cervical spine anomalies, and neurologic deficits in patients with velocardio-facial syndrome. This study was a prospective evaluation of 41 consecutive patients with velocardiofacial syndrome, documented by fluorescence in situ hybridization, between March of 1994 and September of 1998. The 23 girls and 18 boys ranged in age from 0.5 to 15.2 years, with a mean age of 6.7 years. Nineteen patients were assessed with magnetic resonance imaging, 39 underwent lateral cephalometric radiography, and all patients were examined for neurologic deficits. Eight of 19 patients (42 percent) had anomalies of the craniovertebral junction, including Chiari type I malformations (n = 4), occipitalization of the atlas (n = 3), and narrowing of the foramen magnum (n = 1). One patient with Chiari malformation required suboccipital craniectomy with laminectomy and decompression. Fourteen of 41 patients (34 percent) had demonstrated neurologic deficits; 10 patients (24 percent) had velar paresis (6 unilateral and 4 bilateral). Chiari malformations, cervical spine anomalies, and neurologic deficits are common in velocardiofacial syndrome. Because these findings may influence the outcome of surgical intervention, routine assessment of patients with velocardiofacial syndrome should include careful orofacial examination, lateral cephalometric radiography, and magnetic resonance imaging of the craniovertebral junction.     

2型糖尿病患者血糖波动与心律失常和下肢血管病变的关系及其影响因素分析

目的:探讨2型糖尿病(T2DM)患者血糖波动与心律失常和下肢血管病变的关系,分析影响T2DM心律失常和下肢血管病变的因素。方法:选择2019年7月到2020年6月我院收治的82例T2DM患者,根据是否合并心律失常分为心律失常组28例和无心律失常组54例,根据是否合并下肢血管病变分为下肢血管病变组31例和无下肢血管病变组51例。所有患者均通过72 h监测血糖获得日内平均血糖波动幅度(MAGE)、日间血糖平均绝对差(MODD)、全天血糖标准差(SDBG)、全天血糖波动次数(NGE)。比较组间差异,分析影响T2DM患者心律失常和下肢血管病变的因素。结果:心律失常组MAGE、MODD、SDBG、NGE、糖化血红蛋白(HbA1c)、胰岛素抵抗指数(HOMA-IR)、T2DM病程、同型半胱氨酸(Hcy)、丙二醛(MDA)高于无心律失常组(P<0.05)。下肢血管病变组T2DM病程、Hcy、MDA、HOMA-IR、MAGE、MODD、SDBG、NGE均高于无下肢血管病变组(P<0.05)。Logistic回归分析结果显示MDA、HOMA-IR、MAGE、MODD是T2DM患者心律失常的危险因素(P<0.001),MAGE、MODD、SDBG是T2DM患者下肢血管病变的危险因素(P<0.001)。结论:T2DM患者血糖波动与心律失常和下肢血管病变均有关,血糖波动增加是T2DM心律失常和下肢血管病变的危险因素。     

Periorbital lymphatic malformation: clinical course and management in 42 patients

Lymphatic malformation in the orbital cavity and surrounding region often causes disfigurement and visual problems. To better clarify the evolution and treatment of this condition, the authors studied a retrospective cohort of 42 consecutive patients seen between 1971 and 2003 and analyzed anatomic features, complications, and management. The ratio of female to male patients was 1:1. Most periorbital lymphatic malformations were noted at birth (59 percent), presenting as either unilateral swelling (60 percent) or a periorbital mass (24 percent). Sixty-two percent of lesions were on the left side. The ipsilateral cheek, temple, and forehead also were involved in 57 percent of patients. Twenty-two percent of lesions were intraconal, 30 percent were extraconal, and 48 percent were in both spaces. Forty-five percent of children had an associated cerebral developmental venous anomaly. Periorbital lymphatic malformation caused major morbidity; 52 percent of patients had intralesional bleeding and 26 percent of patients had a history of infection. Other common complications included intermittent swelling (76 percent), blepharoptosis (52 percent), proptosis (45 percent), pain (21 percent), amblyopia (33 percent), chemosis (19 percent), astigmatism (17 percent), and strabismus (7 percent). Ultimately, 40 percent of children had diminished vision and 7 percent became blind in the affected eye. Management of periorbital lymphatic malformation involved an interdisciplinary team that included an interventional radiologist, a craniofacial surgeon, and an ophthalmologist. The two therapeutic strategies were sclerotherapy (40 percent) and resection (57 percent); most patients required several interventions. A coronal approach was used for subtotal excision of fronto-temporal-orbital lymphatic malformation in 13 patients, whereas a tarsal incision was used for lesions isolated to the eyelid (n = 14). Ocular proptosis was temporarily managed by tarsorrhaphy (n = 9), but expansion of the bony orbit was needed to correct persistent proptosis (n = 8). Orbital exenteration was necessary in two patients.     

Birdshot retinochoroidopathy

Birdshot retinochoroidopathy is a rare bilateral ocular disorder which typically affects healthy, middle-age caucasians. The typical symptoms are recent onset of bilateral floaters with decreased vision in a white and quiet eye. Minimal anterior chamber reaction, vitreous infiltration without snowballs, and multifocal depigmented lesions in the outer retina and choroid are characteristic of birdshot retinochoroidopathy. Other associated findings include retinal vasculitis, paravascular hemorrhage, vitreous hemorrhage, cystoid macular edema, cellophane maculopathy, posterior subcapsular cataract, optic disc edema, vascular attenuation and tortuosity, optic atrophy and retinal or choroidal neovascularization. Management involves Amsler grid self-assessment and routine funduscopic examinations. A recently documented case of treatment with aromatic retinoids showed improvement while many other commonly prescribed medications are equivocal in effect. Laser photoablation or panretinal photocoagulation are recommended for treatable choroidal or retinal neovascularization, respectively.     

One-stage reconstruction of composite bone and soft-tissue defects in traumatic lower extremities

Management of bone loss that occurs after severe trauma of open lower extremity fractures continues to challenge reconstructive surgeons. Sixty-one patients who had 62 traumatic open lower extremity fractures and combined bone and composite soft-tissue defects were treated with the following protocol: extensive debridement of necrotic tissues, eradication of infection, and vascularization of osteocutaneous tissue for one-stage bone and soft-tissue coverage reconstruction. The mechanism of injury included 49 motorcycle accidents (80.3 percent), five falls (8.2 percent), three crush injuries (4.9 percent), two pedestrian-automobile accidents (3.3 percent), and two motor vehicle accidents (3.3 percent). The bone defects were located in the tibia in 49 patients (79 percent; one patient had bilateral open tibial fractures), in the femur in seven patients (11.3 percent), in the calcaneus bone in four patients (6.5 percent), and in the metatarsal bones in two patients (3.2 percent). The size of soft-tissue defects ranged from 5 x 9 cm to 30 x 17 cm. The average length of the preoperative bony defect was 11.7 cm. The average duration from injury to one-stage reconstruction was 27.1 days, and the average number of previous extensive debridement procedures was 3.4. Fifty patients had vascularized fibula osteoseptocutaneous flaps, six had vascularized iliac osteocutaneous flaps, and five patients had seven combined vascularized rib transfers with serratus anterior muscle and/or latissimus dorsi muscle transfers. One patient received a second combined rib flap because the first combined rib flap failed. The rate of complete flap survival was 88.9 percent (56 of 63 flaps). Two combined vascularized rib transfers with serratus anterior muscle and latissimus dorsi muscle flaps were lost totally (3.2 percent) because of arterial thrombosis and deep infection, respectively. Partial skin flap losses were encountered in the five fibula osteoseptocutaneous flaps (7.9 percent). Postoperative infection for this one-stage reconstruction was 7.9 percent. Excluding the failed flap and the infected/amputated limb, the primary bony union rate after successful free vascularized bone grafting was 88.5 percent (54 of 61 transfers). The average primary union time was 6.9 months. The overall union rate was 96.7 percent (59 of 61 transfers). The average time to overall union was 8.5 months after surgery. Seven transferred vascularized bones had stress fractures, for a rate of 11.5 percent. Donor-site problems were noted in six fibular flaps, in two iliac flaps, and in one rib flap. The fibular donor-site problems were foot drop in one patient, superficial peroneal nerve palsy in one patient, contracture of the flexor hallucis longus muscle in two patients, and skin necrosis after split-thickness skin grafting in two patients. The iliac flap donor-site problems were temporary flank pain in one patient and lateral thigh numbness in the other. One rib flap transfer patient had pleural fibrosis. Transfer of the appropriate combination of vascularized bone and soft-tissue flap with a one-stage procedure provides complex lower extremity defects with successful functional results that are almost equal to the previously reported microsurgical staged procedures and conventional techniques.     

Angioleiomyomas of the extremities: report of a case and review of the Mayo Clinic experience

Angioleiomyomas are rare smooth-muscle tumors that occur anywhere in the body. We present the case of a 46-year-old woman with a 3-year history of a painless angioleiomyoma in the right-hand fourth web space with the typical histologic features of tortuous vascular channels and thick muscular walls. In the 39 cases of angioleiomyoma of an extremity treated at the Mayo Clinic, we found a male-to-female ratio of 1:2.2, a mean age of 52 years, and pain as the presenting symptom in 67 percent of the patients. The lesions usually were less than 1 cm in diameter, and they decreased significantly in size with increasing patient age. Simple excision was curative. Angioleiomyoma should be considered in all patients with nodular lesions of an extremity.     

Persistent splanchnic hyperemia during upright tilt in postural tachycardia syndrome

Previous investigations have allowed for stratification of patients with postural tachycardia syndrome (POTS) on the basis of peripheral blood flow. One such subset, comprising "normal-flow POTS" patients, is characterized by normal peripheral resistance and blood volume in the supine position but thoracic hypovolemia and splanchnic blood pooling in the upright position. We studied 32 consecutive 14- to 22-yr-old POTS patients comprising 13 with low-flow POTS, 14 with normal-flow POTS, and 5 with high-flow POTS and 12 comparably aged healthy volunteers. We measured changes in impedance plethysmographic (IPG) indexes of blood volume and blood flow within thoracic, splanchnic, pelvic (upper leg), and lower leg regional circulations in the supine posture and during incremental tilt to 20 degrees, 35 degrees, and 70 degrees. We validated IPG measures of thoracic and splanchnic blood flow against indocyanine green dye-dilution measurements. We validated IPG leg blood flow against venous occlusion plethysmography. Control subjects developed progressive vasoconstriction with incremental tilt. Splanchnic blood flow was increased in the supine position in normal-flow POTS, despite marked peripheral vasoconstriction, and did not change during incremental tilt, producing progressive splanchnic hypervolemia. Absolute hypovolemia was present in low-flow POTS, all supine flows and volumes were reduced, there was no vasoconstriction with tilt in all segments, and segmental volumes tended to increase uniformly throughout tilt. Lower body (pelvic and leg) flows were increased in high-flow POTS at all angles, with consequent lower body hypervolemia during tilt. Our main finding is selective and maintained orthostatic splanchnic vasodilation in normal-flow POTS, despite marked peripheral vasoconstriction in these same patients. Local splanchnic vasoregulatory factors may counteract vasoconstriction and venoconstriction in these patients. Lower body vasoconstriction in high-flow POTS was abnormal, and vasoconstriction in low-flow POTS was sustained at initially elevated supine levels.     

Histologic investigation of vascular malformations of the face after transarterial embolization with ethibloc and other agents

Twenty-one vascular malformations located in the facial area, 11 high-flow arteriovenous malformations and 10 slow-flow malformations, underwent combined treatment by embolization and later surgery. Embolization was performed simultaneously with superselective angiography of the branches of the external carotid artery. The new biodegradable fibrosing agent Ethibloc was used in 16 cases. Histologic examination of the surgical specimens confirmed the good target orientation by the transarterial injection of Ethibloc. Limitations of this technique are discussed. The agent proved to have thrombogenic and fibrogenic properties. Some of the vascular walls degenerated and ruptured following the embolization, but there were no instances of necrosis of interstitial tissue or skin. Embolization treatment of vascular malformations of the face was not curative, but it facilitated subsequent surgery in all examined cases.     

浊漳河主要污染物时空变化特征

通过对浊漳河流域 1996～ 2 0 0 0年 2 1个监测断面的枯水期 (5月 )、丰水期 (8月 )和平水期 (10月 )地表水采样分析 ,研究了其中主要污染物COD、BOD5、NH3 N、NO2 N和挥发酚的时空变化特征。结果表明 ,污染物浓度随季节变化特征较为复杂 ,但总体表现了枯水期 >平水期 >丰水期的总体特征。污染物沿程变化与各断面接纳不同来源的污染物有关。