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PubMed2005

Smoking and vertical bone defects in a Saudi Arabian population.

PURPOSE: To investigate the relationship between water pipe and cigarette smoking and the prevalence and severity of vertical periodontal bone defects. MATERIAL AND METHODS: A study sample of 355 individuals in the age range 17 to 60 years was recruited from Jeddah, Saudi Arabia. Full sets of intra-oral radiographs for each individual were assessed with regard to the presence or absence of vertical bone defects. A vertical defect was defined as an angular resorption of the interdental marginal bone of 2 mm or more at either the mesial or distal aspect of the root. RESULTS: The overall prevalence of vertical defects was 39%, with a specific prevalence of 47% in water pipe smokers, 54% in cigarette smokers, and 23% in non-smokers. The prevalence was significantly elevated in both types of smokers compared with non-smokers (p < 0.001). Expressed as the proportion of sites with vertical defects per person, the severity was 2.6% for water pipe smokers, 2.8% for cigarette smokers, and 1.3% for non-smokers. The association between smoking and severity of vertical defects was statistically significant (p < 0.001). The severity of vertical defects was significantly greater in heavy exposure compared to light exposure smokers in water pipe as well as cigarette smokers (p < 0.001). The relative risk associated with water pipe and cigarette smoking was 2.9-fold and 6.6-fold increased, respectively, compared to non-smoking. CONCLUSION: The present observations suggest that prevalence and severity of vertical periodontal bone defects are increased in tobacco smokers. The association of vertical bone loss with water pipe smoking is comparable to the association with cigarette smoking.

Adolescent↗
PubMedDate not supplied

[Surgical methods of covering head soft tissues defects].

Posttraumatic and post-excisional head soft tissue defects represent a challenge for the plastic surgeon due to the functional and esthetic impact of this body area. Choosing the simplest way of covering a defect is many times the most efficient way, but it must deliver a good tissue cover and their aspect and function must simulate the characteristics of that area. This article is proposing to be a brief description of all these procedures, informing and being necessary for every general surgeon. The methods of covering head soft tissues defects specific to plastic surgery will be presented in a ladder way from simple to complex, that means from the simple skin graft to island flaps and the tissues transfers. Choosing a right procedure refers to the etiopathogeny, and the length and width of the defect. We shall present advantages and disadvantages of each procedure, indications and their limits, giving specific clinical cases. We shall present the results for each type of procedure also, giving specific arguments for our option. We'll insist on the functional reconstruction of the lids, nose and cheek, as single defects and on the surgical limits which come upon very large soft tissue defects. Due to the complexity of the head structures, either single or complex, and to the functional and esthetic impact of these soft tissue defects, we consider this paper to be a real benefit. It is very important to choose the right procedure, considering all the factors who are implicated (sex, age, general condition, etiopathogeny, the length and width of the defect, previous treatments, patient wish, etc).

Cicatrix↗
PubMed2006

Improved national prevalence estimates for 18 selected major birth defects--United States, 1999-2001.

Continuing efforts are needed to improve surveillance for birth defects, which are the leading cause of infant mortality in the United States. Although state and local surveillance data indicate that approximately 3% of births are affected by any of 45 birth defects, no national estimates based on population-based birth defects surveillance have been available for specific types of birth defects other than neural tube defects (spina bifida and anencephaly). This report describes estimates of national prevalence and number of affected births in the United States each year during 1999-2001 for 18 selected major birth defects. The findings indicated that 10 of the 18 defects affected more than 1,000 infants each year in the United States. The conditions with the highest prevalence included orofacial clefts, which affect approximately 6,800 infants annually, and Down syndrome, which affects approximately 5,500 infants annually. Population-based national prevalence estimates of birth defects can help determine resource needs for basic and public health research and assist in planning for the health-care and educational needs of the U.S. population.

Congenital Abnormalities↗
PubMed2005

Prevalence of enamel defects and MIH in non-fluoridated and fluoridated communities.

AIM: This was to study the prevalence of enamel defects and molar incisor hypomineralisation (MIH) in children attending Leeds Dental Institute (UK) and Westmead Dental Hospital, Sydney (Australia). METHODS: Prospective dental examinations were carried out on 25 children referred to two orthodontic departments. A questionnaire was completed to obtain background information and about previous fluoride (F) exposure followed by an oral examination. First permanent molars and permanent incisors were examined for presence, type and severity of enamel defects using the modified DDE screening index. Chi square tests were used to compare results. RESULTS: Data for 24 children in Sydney and 20 in Leeds presented with at least one enamel defect. Of 300 teeth examined, 155 in Sydney and 82 in Leeds had a defect (p < 0.005). Severity of enamel defects was higher in Sydney. The children presenting with any type of enamel defect in at least one incisor or molar were 21 in Sydney and 10 in Leeds. However, if only demarcated defects were considered, the number in Sydney dropped to 11 and in Leeds remained at 10. CONCLUSIONS: There was a higher prevalence of enamel defects in those children living in F Sydney than in non-F Leeds, but the prevalence of MIH was the same supporting the view that F is not associated with the aetiology of MIH.

Adolescent↗
PubMed2006

[The study of tissue-engineering bone for repair of segmental bone defects].

OBJECTIVE: To investigate the effect of tissue-engineering bone on repair of segmental bone defects. METHODS: Segmental bone defect of 21mm was created at sheep left metatarsus, which was then implanted with tissue-engineering bone (the experimental group) and pure porous beta-TCP (the control group) respectively. The bone defect in the blank group was left without treatment. After the sheep were sacrificed at the 1st, 3rd, or 6th month postoperatively, the samples were taken and examined by radiological, histological and biomechanical methods as well as scanning electron microscopy. The sheep in the blank group were sacrificed at the 6th month postoperatively. RESULTS: The osteoid tissue, woven bone and lamellar bone in the defect of the experimental group occurred earlier than in the control group. The new bone formed directly without through a cartilaginous intermediate in the experimental group, while the defect was repaired in a "creep substitution" way in the control group. At the 6th month, radiological and biomechanical tests revealed nearly complete repair of the bone defect of the experimental group, partial repair in the control group and non-healing in the blank group. CONCLUSIONS: Tissue-engineering bone can repair bone defect, accelerating healing and without "creep substitution", which is a good option in repair of critical segmental bone defects. This study set up a basis for clinical applications in the future.

Animals↗
PubMed2006

[Birth defects occurrence in the Czech Republic in 2003].

OBJECTIVE: An analysis of birth defects occurrence in the Czech Republic in 2003 and a comparison to data from 1996-2002. TYPE OF STUDY: A retrospective analysis of data from a National Register of Congenital Anomalies of the Czech Republic. METHODOLOGY: Data on birth defects in the Czech Republic from the Institute of Health Information and Statistics-National Register of Congenital Anomalies from the 1996-2003 period were used and an analysis of incidences of selected types of birth defects was performed. RESULTS: There were 25,593 children born with a birth defect (14,896 boys and 10,690 girls, in 7 cases the sex was undetermined). A mean incidence of birth defects was 405.2/10,000 live births and remains more or less stable compared to the years 2002 and 2001 (4043/10,000 and 407.9/10,000 live births respectively). CONCLUSIONS: Current data on birth defects in 2003 in the Czech Republic are presented with a comparison to a 8-year period. An analysis of temporal and demographic changes in birth defects incidences is given along with data on prenatal diagnostics and its role in birth defects decrease.

Congenital Abnormalities↗
PubMed2006

[Evaluation on birth defects surveillance system in four counties of Shanxi province, China].

OBJECTIVE: To evaluate the reliability of the birth defects surveillance system in four counties with high prevalence of birth defects (Pingding, Xiyang, Taigu and Zezhou counties) in Shanxi province, China. METHODS: One township was selected from each county as study site. The health workers chosen from township or village level were trained to visit families on the outcomes of each pregnancy who gave birth during year 2003 in the study site. The number of births and cases collected in the study were compared with that from the surveillance system. The number of births reported by surveillance system in four counties was also compared with the data from the local government. The criteria of evaluation were: 1) number of the missing report of births should < or = 5%, 2) the number of missing report on major external birth defects cases should < or = 10%. Researchers from the Peking University were responsible for examining the quality of surveillance in some terminal units of surveillance system. RESULTS: The numbers of births reported in the study and from the surveillance system for four-township were 1043 and 997, respectively. 46 births were missing and the rate of misreporting for births was 4.4%. The numbers of birth defects cases reported in the study and from the surveillance system were 30 and 29, respectively. 1 case of birth defect as missed, and rate of misreporting for birth defects cases was 3.3%. The total number of births reported from surveillance was similar to that in the study in four counties, with a difference of 1.2%. Birth registry data was rather readable and special health workers responsible for surveillance work were present in all the terminal units of the surveillance system. CONCLUSION: The misreporting of births and cases existed in the birth defects surveillance system of the four counties in Shanxi province, but were lower than the allowable criteria. The surveillance units had better registration, reporting and administration of births and birth defect cases. Hence, the quality of the data from the surveillance system in these four counties was reliable.

Birth Certificates↗
PubMed2006

Repairing articular cartilage defects with tissue-engineering cartilage in rabbits.

OBJECTIVE: To investigate the effect of cancellous bone matrix gelatin (BMG) engineered with allogeneic chondrocytes in repairing articular cartilage defects in rabbits. METHODS: Chondrocytes were seeded onto three-dimensional cancellous BMG and cultured in vitro for 12 days to prepare BMG-chondrocyte complexes. Under anesthesia with 2.5% pentobarbital sodium (1 ml/kg body weight), articular cartilage defects were made on the right knee joints of 38 healthy New Zealand white rabbits (regardless of sex, aged 4-5 months and weighing 2.5-3 kg) and the defects were then treated with 2.5% trypsin. Then BMG-chondrocyte complex (Group A, n=18), BMG (Group B, n=10), and nothing (Group C, n=10) were implanted into the cartilage defects, respectively. The repairing effects were assessed by macroscopic, histologic, transmission electron microscopic (TEM) observation, immunohistochemical examination and in situ hybridization detection, respectively, at 2, 4, 8, 12 and 24 weeks after operation. RESULTS: Cancellous BMG was degraded within 8 weeks after operation. In Group A, lymphocyte infiltration was observed around the graft. At 24 weeks after operation, the cartilage defects were repaired by cartilage tissues and the articular cartilage and subchondral bone were soundly healed. Proteoglycan and type II collagen were detected in the matrix of the repaired tissues by Safranin-O staining and immunohistochemical staining, respectively. In situ hybridization proved gene expression of type II collagen in the cytoplasm of chondrocytes in the repaired tissues. TEM observation showed that chondrocytes and cartilage matrix in repaired tissues were almost same as those in the normal articular cartilage. In Group B, the defects were repaired by cartilage-fibrous tissues. In Group C, the defects were repaired only by fibrous tissues. CONCLUSIONS: Cancellous BMG can be regarded as the natural cell scaffolds for cartilage tissue engineering. Articular cartilage defects can be repaired by cancellous BMG engineered with allogeneic chondrocytes. The nature of repaired tissues is closest to the normal cartilage. Local administration of trypsin can promote the adherence of repaired tissues to host tissues. Transplantation of allogeneic chondrocytes has immunogenicity, but the immune reaction is weak.

Animals↗
PubMed2006

[Treatment of deep cartilage defects of the knee with autologous chondrocyte transplantation on a hyaluronic Acid ester scaffolds (Hyalograft C)].

PURPOSE OF THE STUDY: The treatment of chondral defects by transplantation of autologous chondrocytes has recently shown further development. Various biomaterials are used as carriers facilitating attachment and even distribution of chondrocytes in the defect. Since 2003 Hyalograft C, hyaluronan-based scaffolds, has been used, in a clinical study, for implantation of autologous chondrocytes in the treatment of deep chondral lesions of the knee at our department. MATERIAL: Eight patients (7 men and 1 woman; average age, 31 years) followed up for at least 9 months were evaluated. The lesions with an average size of 3.9 cm2 were localized on femoral condyles. METHODS: The outcome of surgery was evaluated on the basis of the IKDC Subjective Knee Evaluation Form, Knee Injury and Osteoarthritis Outcome Score (KOOS) and Lysholm knee score. The patients underwent MR examination preoperatively and at 3, 6 and 12 months after surgery. The newly-formed cartilage was assessed by International Cartilage Repair Society (ICRS) visual scores at second-look arthroscopy carried out at 9 to 12 months following transplantation. Consistency of the new cartilage developing in the defect and that of healthy cartilage around the defect was compared by means of a special indentation probe in three patients. A biopsy sample was collected from the grafted site for histological, histochemical and immunohistochemical examination. RESULTS: All patients reported improvement in knee function on average at 10 months after surgery. The average IKDC subjective score increased from 46 points preoperatively to 74 points postoperatively. The KOOS evaluation showed pain relief and improved function. In quality of life evaluation the average score of 35 points before surgery increased to 70 points after it. The average Lysholm knee score was 61 points before and 83 points after surgery. MR findings correlated well with arthroscopic findings. Second-look arthroscopy showed a normal appearance of the newly-formed cartilage in six, and an abnormal appearance in two patients. The average ICRS visual score was 9.4 points. No graft failure was recorded. The newly-produced tissue had the histological characteristics of a mixed hyaline and fibrous cartilage in seven patients, and of hyaline-like cartilage in one patient. DISCUSSION: The ICRS visual repair assessment of the newly-formed tissue showed that our results were better than the one-year outcomes reported by Bartlett et al. (11 patients after transplantation of a collagen bilayer seeded with chondrocytes), but worse than the results of an Italian multi-center study (55 patients with Hyalograft C-based grafts followed up on average for 14 months). At almost one year, implantation of on a Hyalograft C resulted in the production of mixed cartilage incorporated well in the subchondral bone. Only one patient had mature hyaline cartilage. One year is too short to allow for complete remodeling of the newly formed cartilage into a mature hyaline cartilage. This is in agreement with other studies suggesting that the new cartilage continues to mature and remodel for a time longer than one year. CONCLUSIONS: Based on our results we suggest that the use of Hyalograft C is a safe and effective option for treatment of deep chondral defects of the knee; it is particularly useful in patients in whom the primary defect treatment has failed. The application of Haylograft C is relatively quick and easy; this is convenient when surgery involves more than one procedure (ligament reconstruction, osteotomy). However, a definite evaluation of this method will be possible only after long-term results are available. Key words: deep cartilage defects, chondral defects, cartilage repair, autologous chondrocyte transplantation, hyaluronan- based scaffold, Hyalograft C, cartilage repair assessment, ICRS.

Adult↗
PubMed2006

Vigabatrin-attributable visual field defects in patients with intractable partial epilepsy.

INTRODUCTION: Vigabatrin (VGB) is implicated to cause visual field defects. We estimated the prevalence, described the characteristics and investigated the risk factors of VGB-attributable visual field defects. METHODS: Patients with intractable partial epilepsy under VGB add-on treatment received static perimetric examinations. Visual field charts were reviewed and interpreted using a three-grade system. Clinical features and therapeutic courses were analyzed for possible risk factors. RESULTS: Visual field defects in at least one eye were detected in 27 (79%) of 34 patients. In the subgroup of 27 patients with both eyes reliably tested, 16 (59%) had bilateral defect, among whom seven were severely involved and showed nasally dominant, crescent or concentric defect. Five patients had unilateral visual field defects. Four out of the 27 affected patients reported blurred vision. No statistically significant differences were noted between patients with and without visual field defects in terms of gender, age, duration or etiology of the epilepsy, and duration, maximum daily dose, or cumulative dose of VGB. CONCLUSIONS: There was a high prevalence of VGB-attributable visual field defects. No risk factors could be identified. Routine initial and regular follow-up of visual field examination, especially that focusing within a range of central fixation to 60 degrees, should be performed in patients on VGB.

Adult↗
PubMed2006

[Frequency and layout of congenital defects in infants born from 1991 to 1995 and from 2000 to 2004 at the Obstetrics and Gynecology Department of Wolomin District Hospital].

OBJECTIVE: The aim of the study was an evaluation of the frequency and distribution of congenital malformations in infants born at the Obstetrics and Gynecology Department of Wołomin District Hospital in the years 1991-95 and 2000-2004 and a comparison of occurrence frequency of defects' types in the analyzed periods. METHODS: The study comprises an evaluation of documentations of 5649 infants born in the years 1991-1995 and 6049 infants born in the years 200-2004, 11698 infants in total. In the study groups of infants, the frequency of congenital malformation occurrence was analyzed. RESULTS: The majority of congenital malformation diagnosis in the years 1991-1995 were CNS defects with 21% and the second most frequent group were facial skeleton defects with 16% The majority of congenital malformation diagnosis in the years 2000-2004 were osteoarticular system defects (25%) and the second most frequent group were organic heart diseases with 14%. CONCLUSIONS: The frequency and distribution of congenital defects was comparable with data provided by other authors. The most frequent defects were osteoarticular system defects, congenital hart dsefects and CNS. An increase in number of defects of the osteoarticular system was observed.

Abnormalities, Multiple↗
PubMed2006

[Articular cartilage defects repaired with homograft of mesenchymal stem cells seeded onto medical collagen membrane of guided tissue regeneration].

OBJECTIVE: To investigate the curative effects of homograft of the mesenchymal stem cells (MSCs) combined with the medical collagen membrane of the guided tissue regeneration(MCMG) on the full thickness defects of the articular cartilage. METHODS: MSCs derived from New Zealand rabbits aged 3-4 months weighing 2. 1-3.4 kg were cultured in vitro with a density of 5.5 x 10 (8)/ml and seeded onto MCMG. The MSC/MCMG complex was cultured for 48 h and transplanted into the full thickness defects on the in board condyle and trochlea. Twenty-seven healthy New Zealand rabbits were randomly divided into 3 groups of 9 rabbits in each. The cartilage defects in the in board condyle and trochlea were filled with the auto bone marrow MSCs and MCMG complex (MSCs/ MCMG) in Group A (Management A), with only MCMG in Group B (Management B) and with nothing in Group C (Management C). Three rabbits were killed at 4, 8 and 12 weeks after operation in each group, and the reparative tissue samples evaluated grossly,histologically and immunohistochemically were graded according to the gross and histological scale. RESULTS: Four weeks after transplantation, the cartilage and subchondral bone were regenerated in Group A; for 12 weeks, the regenerated cartilage gradually thicker; 12 week after transplantation, the defect was repaired and the structures of the articular surface and subchondral bone was.in integrity. The defects in Group A were repaired by the hyaline-like tissue and the defects in Groups B and C were repaired by the fibrous tissues. Glycosaminoglycan and type II collagen in Groups A, B and C were reduced gradually. The statistical analysis on the gross at 12 weeks and the histological gradings at 4 weeks, 8 weeks and 12 weeks showed that the in board condylar repair had no significant difference compared with the trochlearepair(P>0. 05). Management A was significantly better than Managements B and C (P<0. 05), and Management B was better than Management C (P<0. 05). CONCLUSION: Transplantation of the MSCs combined with MCMG on the full thickness defects of the articular cartilage is a promising approach to the the treatment of cartilage defects. MCMG can satisfy the demands of the scaffold for the tissue-engineered cartilage.

Animals↗
PubMed1991

Defects in the bony wall of the mastoid bowl: a study based on staged intact canal-wall tympanoplasty.

The incidence and outcome of bony wall defects in the mastoid bowl were studied in 175 ears of 167 patients who underwent staged tympanoplasty by the intact canal-wall technique. In the first stage, the middle fossa dura was exposed iatrogenically in 38 ears and pathologically in eight ears through a defect at the tegmen. In the second stage, the bone defect was cured in 27 ears of the former group and in 3 ears of the latter group. The overall cure rate of the defect in the tegmen during these stages was 65.2 percent (30/46). Exposure of the sigmoid sinus or posterior fossa dura, which had occurred iatrogenically in 12 ears in the first stage, was cured in 11 ears (91.7%) in the second stage. Defects of the anterior wall of the mastoid bowl, i.e., the posterior wall of the external auditory canal, were recognized in 105 ears in the first stage, 91 of which involved pathologic defects of the tympanic scutum caused by cholesteatoma. In the second stage, these defects remained unhealed with cures occurring in only two ears (1.9%), in which a small hole had been created iatrogenically in the middle of the canal wall. Defects in the canal wall due to bone resorption following the first stage operation were noted in the second stage in 26 of 175 ears (14.9%).

Adolescent↗
PubMed1991

Experimental coating defects in hydroxylapatite-coated implants.

Defects in hydroxyapatite (HA)-coated metallic implant systems, including cracks, flakes, or scratches, may occur at the time of surgery or in time because of in vivo loading. Such defects may affect the bone-implant interface response because of increased local metallic corrosion and ion release. Using a canine transcortical push-out model, the interface mechanics and histology of HA-coated titanium and cobalt-chromium-molybdenum alloy implants with and without coating defects were evaluated. The coating defects extended through the HA material to the underlying metallic substrate. Interface mechanical testing and undecalcified histologic techniques were used to evaluate differences in interface response at three, five, six, ten, 12, and 32 weeks postimplantation. There were no statistically significant differences between the HA-coated implants with and without defects for either interface shear strength or stiffness; however, both HA-coated implant types developed significantly greater interface strength and stiffness when compared to uncoated metallic implants. Histologically, in all areas away from the defect, a progression to nearly complete mineralization of osseous tissue directly onto the HA-coated surface was observed with no interpositional fibrous tissue layer. At early time periods (up to six weeks) in the area of the coating defect, bone apposition and mineralization appeared to stop at the edge of the HA coating. At later time periods (greater than ten weeks), the area of the defect was filled with mineralized osseous tissue in approximately one-half of the specimens. A thin fibrous interpositional layer was observed at the interface of the exposed metal substrate.

Analysis of Variance↗
PubMed1991

The surgical anatomy of double-outlet right ventricle with concordant atrioventricular connection and noncommitted ventricular septal defect.

In describing hearts with double-outlet right ventricle, we have had problems with how best to use the term noncommitted as applied to the ventricular septal defect. We reviewed, therefore, 63 hearts with double-outlet right ventricle in the setting of usual atrial arrangement and a concordant atrioventricular connection. From these, 18 hearts with potentially noncommitted defects were identified and studied in detail. The defect was unequivocally remote from the ventricular outflow tracts in 16 of these hearts, being perimembranous with excavation to open into the inlet of the right ventricle in 12, two of these also having straddling of an atrioventricular valve. One heart had a muscular defect situated in the inlet part of the muscular septum, whereas the defect was the ventricular component of an atrioventricular septal defect in the other three. In the remaining two hearts the defect was anatomically juxtaposed to a subarterial outlet. The pathway to the outflow tract, however, was obstructed by leaflets of a straddling valve. Our study shows, therefore, the need to distinguish between anatomic "commitment" of the defect from the problems in terms of commitment that may confront the surgeon in the operating room. Not only does the distance between the interventricular communication and one of the subarterial outflow tract need to be assessed (the anatomic commitment), but also the presence and nature of any intervening extraneous tissues (the surgical commitment) requires assessment.

Double Outlet Right Ventricle↗
PubMed1990

[Microsurgical repair of heel and sole defects].

Since 1984, microsurgical technique has been applied to reconstruct and repair the defects of heel and sole in 21 cases by replantation and implantation. Among them, 12 cases were heel defects, 3 cases were fore-sole defects and 6 cases were complete sole defects. Emergency repair and reconstruction has been performed in 13 cases and late reconstruction in 8 cases. All flaps survived. Our main experiences were: 1. All sorts of defected tissues should be reconstructed at the same time. 2. The selection of donor area should be according to the principles:lateral or medial leg flap should be used for moderate defects; lateral thoracic flap for large defects; and the flap of center sole for small defects. 3. Debridement of focus should be done thoroughly.

Adolescent↗
PubMed1990

[Exercise-induced thallium-201 myocardial perfusion defects in angina pectoris without significant coronary artery stenosis].

We performed exercise thallium-201 myocardial scintigraphy in 32 patients with angina pectoris to study the incidence of perfusion defects, who had no significant organic stenosis on coronary angiography. None of them had myocardial infarction or cardiomyopathy. Thallium-201 myocardial scintigraphy and 12-lead ECG recording were performed during supine bicycle ergometer exercise. Perfusion defects in thallium-201 scintigrams in SPECT images were assessed during visual analysis by two observers. In the coronary angiograms obtained during intravenous infusion of nitroglycerin, the luminal diameter of 75% stenosis or less in the AHA classification was regarded as an insignificant organic stenosis. Myocardial perfusion defects in the thallium-201 scintigrams were detected in eight (25%) of the 32 patients. Six of these eight patients had variant angina documented during spontaneous attacks with ST elevations in standard 12-lead ECGs. Perfusion defects were demonstrated at the inferior or inferoposterior regions in six patients, one of whom had concomitant anteroseptal defect. The defects were not always accompanied by chest pain. All but one patient demonstrating inferior or inferoposterior defects showed ST depression in leads II, III and aVF on their ECGs, corresponding to inferior wall ischemia. The exception was a case with right bundle branch block. Thus, 25% of the patients with angina pectoris, who had no evidence of significant organic stenosis on their coronary angiograms, exhibited exercise-induced perfusion defects in their thallium-201 scintigrams. Coronary spasms might have caused myocardial ischemia in these patients.

Adult↗
PubMed1990

High von Willebrand factor concentration compensates a relative adhesion defect in uremic blood.

Uremia is associated with a bleeding diathesis. We investigated platelet adhesion as a cause for the impaired primary hemostasis and the role of von Willebrand factor (vWF) in this process in uremic patients. Perfusions with blood with standardized hematocrit, platelet count, and free Ca2+ ions were performed over inverted and deendothelialized artery segments from human umbilical cords in a modified Baumgartner perfusion chamber. Platelet adhesion in patient perfusates was comparable with control adhesion. However, the high vWF levels present in uremic whole blood did not increase adhesion above the adhesion in control blood with lower vWF levels. These results suggested that a relative adhesion defect was present in patient blood. Control blood in which vWF levels were raised to uremic levels showed the high adhesion that uremic whole blood failed to show. Additionally, in perfusions with uremic plasma in which the initially high vWF level was normalized by dilution with vWF-depleted uremic plasma, adhesion was clearly lower than in normal plasma. Washed patient platelets did not differ from normal platelets in their association with purified vWF, via their adhesion receptors glycoprotein Ib and IIb-IIIa. Patient platelets present in patient plasma showed a similar adhesion defect as control platelets, which were resuspended in the uremic plasma. Therefore, primary defects of uremic platelets were of minor importance for the observed adhesion defect in uremic whole blood. The adhesion defect was not dependent on the presence of uremic vWF; plasma of uremic patients depleted of vWF also inhibited adhesion, and the defect remained present when purified control vWF was added to vWF-depleted uremic plasma. The binding of uremic vWF to the vessel wall and its support of subsequent adhesion were not impaired. These results indicate that the observed adhesion defect was not due to abnormal vWF. Our current results suggest an unknown component present in uremic plasma that directly inhibits platelet interaction with artery segments; however, it has no effect on vWF binding to the vessel wall. High vWF levels in uremic plasma are able to compensate for the defect.

Adult↗