Biomedical subjects

M J Post

Publications and source records attributed to M J Post.

At least 55 records · Page 3Linked to original sources

PubMed1995

Paradoxical arterial wall shrinkage may contribute to luminal narrowing of human atherosclerotic femoral arteries.

BACKGROUND: This study was done to assess how local changes in vessel size, together with plaque load, determine luminal narrowing in atherosclerotic arteries. Fifty-one human femoral arteries were analyzed: 32 postmortem and 19 in vivo by 30-MHz intravascular ultrasound. METHODS AND RESULTS: Histological and intravascular ultrasound cross sections were examined every 0.5 cm over an arterial segment 10 to 15 cm long. In each cross section we measured the lumen area and the area circumscribed by the internal elastic lamina (the IEL area). In each arterial segment, the cross section that contained the least amount of plaque was the reference site. For each cross section, the lumen area stenosis was expressed as percent of the lumen area in the reference site. Similarly, the IEL area was expressed as percent of the IEL area in the reference site (the relative IEL area). There was a significant negative correlation between the relative IEL area and the lumen area stenosis percentage (r = -.62, P < .001 for histology and r = -.66, P < .001 for intravascular ultrasound). When lumen area stenosis was less than about 25%, mainly compensatory enlargement was observed. When lumen area stenosis exceeded about 25%, however, mainly a decrease of the IEL area was observed, which is consistent with arterial wall shrinkage. Furthermore, the increase in plaque area does not account for the total loss of luminal area. There was a moderate correlation between an increase in plaque area and reduction of the corresponding lumen area (r = .49 and r = .56 for histology and intravascular ultrasound, respectively). CONCLUSIONS: The decrease in luminal area cannot be attributed to plaque increase alone. Arterial wall shrinkage is a paradoxical mechanism that may contribute to severe luminal narrowing of the atherosclerotic human femoral artery.

Aged↗

PubMed1995

Remodeling of De Novo atherosclerotic lesions in femoral arteries: impact on mechanism of balloon angioplasty.

OBJECTIVES: Using 30-MHz intravascular ultrasound in the human femoral artery, we related the mode of arterial remodeling to the immediate result and the mechanism of balloon angioplasty. BACKGROUND: The atherosclerotic femoral artery may undergo three modes of remodeling in response to plaque formation: compensatory enlargement, failure of compensatory enlargement and paradoxic shrinkage. METHODS: In 83 patients an ultrasound catheter pullback maneuver was performed before and after balloon angioplasty. For each lesion (n = 121), the cross section with the narrowest lumen was selected for further analysis. For each cross section, the lumen area stenosis was expressed as percent of the lumen area at an adjacent reference site. Similarly, the media-bounded area was expressed as percent of the media-bounded area at the reference site. Cross sections were classified into one of three groups based on percent relative media-bounded area: 1) > 105% (group A, compensatory enlargement, n = 24); 2) 95% to 105% (group B, failure of compensatory enlargement, n = 26); and 3) < 95% (group C, arterial wall shrinkage, n = 71). The power of the present study was 99.3% to demonstrate a difference in lumen gain of 2.5 mm2 among groups. RESULTS: The gain in lumen area induced by balloon angioplasty did not differ significantly among the three groups (group A, 7.0 +/- 4.0 mm2 [mean +/- SD]; group B, 8.6 +/- 4.8 mm2; group C, 8.9 +/- 4.9 mm2). Stretch of the media-bounded area was observed in all three groups, but it was significantly larger in group C (7.5 +/- 5.2 mm2) than in the other two groups (group A, 3.9 +/- 5.1 mm2; group B, 5.1 +/- 4.1 mm2). A significantly positive correlation between balloon/media-bounded area ratio and elastic recoil was observed for cross sections in groups A and B (r = 0.71 and r = 0.69, respectively). However, no correlation was observed between balloon/media-bounded area ratio and elastic recoil for cross sections in group C (r = 0.17). CONCLUSIONS: We conclude that lumen gain by balloon angioplasty is not related to the mode of atherosclerotic arterial remodeling. However, the mode of arterial remodeling affects the dilation mechanism.

Aged↗

PubMed1995

Discrimination of intravascular lumen and dissections in single intravascular ultrasound images using subtraction, conventional averaging and saline flush.

With current 30-MHz intravascular ultrasound systems, flowing blood may cause considerable backscatter which in real-time images is characterized by dynamic speckle. However, in a single intravascular ultrasound image (still-frame) the discrimination between arterial lumen and wall may be difficult due to the frozen intraluminal speckle, particularly in the presence of dissections. We compared subtraction, averaging and saline flush as methods to improve the discrimination between arterial lumen and wall in a single image. The real-time images served as gold standard. In 22 patients who underwent peripheral balloon angioplasty, ultrasound images obtained from 84 sites were examined. The sensitivity and specificity of detecting dissections were in the subtraction image 85% and 100%, in the averaged image 57% and 96%, and in the saline flush image 58% and 86%, respectively. Subtraction is a promising method to outline the irregular lumen in a single image.

Aged↗

PubMed1995

Radiographic evaluation of AIDS patients.

Morphological imaging, based on the use of various techniques including ultrasound, X-ray computed tomography (CT), and magnetic resonance imaging (MRI), plays an important role in the characterization, diagnosis and follow-up of patients with human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS). While the presence of thoracic infections, the most frequently observed illnesses in AIDS patients, can best be performed by using conventional chest films and CT, the assessment of cerebral involvement in AIDS patients--characterized by the presence of focal masses, demyelination, meningitis, and infarction--is best achieved using MRI. The work-up of patients with gastrointestinal symptoms should include the use of ultrasound for the evaluation of visceral involvement and lymphadenopathy, completed by CT to further characterize pathologic conditions in either the bowel or visceral organs. Ultrasound is the screening exam of choice in AIDS patients with suspected renal disease, but other methods may be necessary for the assessment of the complications due to pharmacological treatment. Musculoskeletal complications may require the combined use of all the above methods, since they may be caused by infections, tumors and rheumatologic illness. The use of the radiographic methods for the detection of the numerous forms of infections and malignancies in AIDS patients is described in detail for the various body districts.

AIDS-Related Opportunistic Infections↗

PubMed1995

Neurosyphilis in HIV-positive and HIV-negative patients: neuroimaging findings.

PURPOSE: To evaluate and describe the neuroimaging findings of patients with neurosyphilis. METHODS: The neuroimaging studies of 35 patients with documented neurosyphilis were reviewed. Diagnosis was established in 34 patients with cerebrospinal fluid for a Venereal Disease Research Laboratory test, complemented by autopsy in 1 and brain biopsy in 1. All patients had reactive fluorescent treponemal antibody tests with absorption in their sera. Imaging studies included plain and contrast-enhanced CT of the brain, plain and gadolinium-enhanced MR, MR angiography, and conventional angiography. Imaging findings were also correlated with the relevant pathologic findings at autopsy in three additional patients with neurosyphilis who did not have brain imaging studies. RESULTS: Of the 35 patients with imaging studies, 32 tested human immunodeficiency virus (HIV)-seropositive, and 3 were HIV-seronegative. Eleven (31%) of 35 patients had normal radiographic findings. Cerebral infarctions were seen in 8 (23%) of 35 patients, and nonspecific white matter lesions in 7 (20%) of 35. Cerebral gummas and extraaxial enhancement indicating meningitis were noted in 2 (6%) of 35 patients, respectively. Arteritis was demonstrated in 2 (50%) of 4 patients who underwent either MR angiography or conventional angiography. The 3 subjects who had autopsy but not imaging studies were found to have manifestations of meningovascular syphilis, including syphilitic leptomeningitis and an obliterative endarteritis. CONCLUSION: We conclude that findings of vascular occlusive disease manifested as infarction or arteritis, enhancing cortical lesions with or without adjacent meningeal enhancement, focal or diffuse extraaxial enhancement, and white matter disease, although nonspecific, in the proper clinical setting should prompt appropriate testing for neurosyphilis, a treatable disease, in patients with and without HIV infection.

AIDS Dementia Complex↗

PubMed1995

MR-pathologic comparisons of wallerian degeneration in spinal cord injury.

PURPOSE: To describe the MR manifestations and temporal course of wallerian degeneration that occurs above and below a spinal cord injury, and to compare the MR findings with postmortem histopathology. METHOD: Twenty-four postmortem spinal cords from patients with cervical (n = 14), thoracic (n = 6), and lumbar (n = 4) cord injuries were studied with axial T1- and T2-weighted spin-echo MR imaging. Injury-to-death intervals varied from 8 days to 23 years. The images were examined for alteration of signal above and below the injury site. Histologic studies of these cords with axon, myelin, and connective tissue stains were performed at levels equivalent to the MR sections. Immunohistochemical analysis using antibodies to glial fibrillary acetic protein was also performed on 19 cords. Pathologic-imaging comparisons were made. RESULTS: MR images showed increased signal intensity in the dorsal columns above the injury level and in the lateral corticospinal tracts below the injury level in all cases in which cord injury had occurred 7 or more weeks before death. In early postinjury survival times (8 days and 12 days) MR findings were normal; histologically there was early wallerian degeneration in only the dorsal columns at 8 days and in both the lateral and dorsal columns at 12 days. MR showed wallerian degeneration in all cases examined at 7 weeks after injury and thereafter. CONCLUSIONS: Wallerian degeneration was demonstrated by histology and MR in all specimens in which the injury-to-death interval was greater than 7 weeks. Recognition of wallerian degeneration on MR allows complete analysis of the injury, explains abnormal MR signals at sites remote from the epicenter of the injury, and may be useful in the future in the timing and planning of therapeutic interventions.

Adolescent↗

PubMed1995

Arterial remodeling in atherosclerosis and restenosis: a vague concept of a distinct phenomenon.

Geometric remodeling in atherosclerosis and restenosis comprises a change of the total arterial circumference that, together with plaque growth or neointima formation, determine the lumen of the artery. The change in total arterial circumference relative to a reference cross section ranges from excessive enlargement with an actual increase in lumen to a shrinkage contributing to lumen narrowing. The forces that determine whether an artery shrinks or is able to enlarge as a consequence of atherosclerotic lesions or of post-interventional intimal hyperplasia are unknown but are likely to affect matrix and specifically collagen redistribution. Identifying these forces is of importance because they might be used to promote favorable remodeling. The cellular and humoral triggers of collagen degradation and synthesis, as well as conformation changes of collagen matrices after their deposition, need to be investigated. As with injury-induced intimal hyperplasia and plaque growth in de novo atherosclerosis, injury models may serve as a paradigm for geometric remodeling in atherosclerosis.

Angioplasty↗

PubMed1994

Progressive multifocal leukoencephalopathy complicating Wiskott-Aldrich syndrome. Report of a case and review of the literature of progressive multifocal leukoencephalopathy with other inherited immunodeficiency states.

OBJECTIVE: To describe the occurrence of progressive multifocal leukoencephalopathy (PML) in association with Wiskott-Aldrich syndrome, an X-linked recessive disorder with impairment of both cellular and humoral immunity. DESIGN: A detailed analysis of this patient's clinical illness, immunologic factors, neuroradiographic findings, and brain histopathologic conditions was undertaken. The medical literature on PML complicating congenital immunodeficient states was also reviewed. SETTING: A 1500-bed, university-affiliated, public health hospital. PATIENT: A 15-year-old boy with Wiskott-Aldrich syndrome. His neurologic illness was heralded by dysarthria and right-sided weakness and the diagnosis was established by brain biopsy specimen. Survival from the time of onset of PML was 10 months. CONCLUSION: Although PML typically occurs in the setting of severe acquired cellular immunodeficiency, often as a consequence of acquired immunodeficiency syndrome, organ transplantation, and leukemia and lymphoma, it may rarely accompany inherited immunodeficiency syndromes. The reported childhood cases of PML include three patients, aged 5, 11, and 18 years, with other inherited immunodeficiency syndromes. This patient represents the first time (to our knowledge) that PML has been reported to occur in association with Wiskott-Aldrich syndrome.

Adolescent↗

PubMed1994

The relative importance of arterial remodeling compared with intimal hyperplasia in lumen renarrowing after balloon angioplasty. A study in the normal rabbit and the hypercholesterolemic Yucatan micropig.

BACKGROUND: Although arterial renarrowing after angioplasty has been attributed largely to intimal hyperplasia, there has been no systematic effort to correlate the actual hyperplastic tissue mass with angiographic lumen reduction. Using balloon angioplasty in various animal restenosis models, we quantitatively assessed the separate contributions of intimal hyperplasia and arterial remodeling to angiographic late lumen loss. METHODS AND RESULTS: Data used for this study were obtained from experiments of conventional and thermal (37 degrees C or 55 degrees to 90 degrees C) balloon angioplasty-treated femoral and iliac arteries in normal rabbits and conventional balloon angioplasty-treated iliac arteries in Yucatan micropigs fed either a normal or an atherogenic diet. Quantitative angiography was performed immediately before and after intervention and at 3 or 8 weeks thereafter, and late loss in lumen diameter was taken as the difference between arterial diameter immediately after treatment and at 3 or 8 weeks of follow-up. Intimal hyperplasia was quantified histologically as the area of tissue mass within the internal elastic lamina. We observed a consistent discrepancy between the actual late loss seen with angiography and the diameter reduction that could be explained by histological intimal thickness alone in both animal models. This discrepancy ranged from 86 +/- 3% of the late loss in the 8 weeks/37 degrees C group to 77 +/- 22% in the conventional group for rabbits and 52 +/- 23% in an atherogenic diet group (n = 10) to 89 +/- 11% in a normal diet group (n = 6) for pigs. This discrepancy appeared to be due predominantly to reduction of the area circumscribed by the internal elastic membrane, a process that is tentatively designated as arterial remodeling. In both the rabbit femoral artery and in the Yucatan iliac artery, remodeling, not intimal hyperplasia, correlated with angiographic late loss. CONCLUSIONS: In both the normal rabbit and the normal and atherosclerotic pig, restenosis after angioplasty results from both intimal hyperplasia and arterial remodeling. The exact etiology of arterial renarrowing after angioplasty has important implications on the design of antirestenosis drugs and new coronary devices.

Angioplasty, Balloon↗

PubMed1994

Use of thallium-201 brain SPECT to differentiate cerebral lymphoma from toxoplasma encephalitis in AIDS patients.

PURPOSE: To determine whether thallium-201 brain single-photon emission CT could be used to make the distinction between central nervous system lymphoma and toxoplasma encephalitis, which may not be possible by routine MR and CT. METHODS: A total of 37 patients with acquired immunodeficiency syndrome who had intracranial mass lesions found during a 9-month prospective study by either MR or CT underwent further evaluation with Tl-201 brain single-photon emission CT. RESULTS: Twelve patients had increased intense focal Tl-201 uptake. All of these patients had either biopsy- or autopsy-proven lymphoma. Twenty-five of the patients studied had no Tl-201 brain uptake in the lesion(s); 24 of these patients had toxoplasma encephalitis on clinical follow-up. One patient with no Tl-201 uptake was found by cerebrospinal fluid analysis to have mycobacterium tuberculosis abscess. CONCLUSION: Patients with acquired immunodeficiency syndrome who have intracranial mass lesions on MR or CT may benefit from Tl-201 brain single-photon emission CT because it can help distinguish between lymphoma and infectious lesions such as toxoplasma encephalitis.

AIDS Dementia Complex↗

PubMed1994

Acute spinal subdural hematoma: MR and CT findings with pathologic correlates.

PURPOSE: To determine the MR and CT findings that characterize acute spinal subdural hematoma (ASSH). METHODS: The MR, CT, and clinical findings in three patients with surgically proved ASSH were reviewed and also correlated with the postmortem MR, CT, and cryomicrotome findings in three other patients, two with ASSH and one with an acute spinal epidural hematoma. RESULTS: Imaging findings in ASSH included: (a) hyperdense lesions on plain CT within the dural sac, distinct from the adjacent low-density epidural fat and silhouetted against the lower-density spinal cord and cauda equina, which it compressed; (b) lack of direct continuity with the adjacent osseous structures; (c) clumping, loculation, and streaking of blood within the dural sac on both MR and Ct; and (d) an inhomogeneous and variable signal intensity to the ASSH on all MR pulse sequences, but, nevertheless, a striking low signal intensity on T2-weighted spin-echo or T2-weighted gradient-echo to a major part of the ASSH because of deoxyhemoglobin. Plain CT was most helpful in compartmentalizing the hematoma. CONCLUSION: When MR and plain CT are obtained as complementary studies, they provide characteristic findings that allow the prompt diagnosis of ASSH.

Adult↗

PubMed1994

Progressive posttraumatic myelomalacic myelopathy: imaging and clinical features.

PURPOSE: To describe the imaging features, surgical management, and clinical outcome of progressive posttraumatic myelomalacic myelopathy (PPMM), a relatively unrecognized but important cause of progressive myelopathy in patients with previous spinal cord injuries. METHODS: The clinical records, imaging studies, and postoperative outcome of 10 patients with PPMM were reviewed. Fifteen preoperative and five postoperative MRs were analyzed for intramedullary signal abnormalities, the nature of these signal abnormalities, and cord tethering. All patients had intraoperative sonography. RESULTS: Neurologic signs and symptoms found in our patients included 1) progressive loss of motor function (6/10), 2) sensory level changes (4/10), 3) increased spasticity (4/10), 4) autonomic dysreflexia (4/10), 5) loss of bowel or bladder control (4/10), and 6) local and/or radicular pain (4/10). Preoperative MR in nine patients revealed intramedullary T1/T2 lengthening (9/9), extramedullary tethering/adhesions (9/9), ill-defined lesional borders (6/9), cord expansion (5/9), and increased signal intensity of the lesion on T1-weighted images compared with CSF (7/9). Proton density images in five patients demonstrated a relative increase in signal intensity over CSF. In all five postoperative MRs, there was evidence of untethering of the spinal cord and a decrease in cord size in two patients. Intraoperative sonography revealed cord tethering and abnormal cord echotexture in all cases. Postoperative clinical evaluation revealed neurologic improvement in nine patients. CONCLUSIONS: PPMM may clinically and radiographically mimic progressive posttraumatic cystic myelopathy (PPCM). MR provides clues to the diagnosis of myelomalacia preoperatively. Intraoperative sonography confirms the absence of a confluent cyst. These points are crucial in the surgical procedures in PPMM vs PPCM. In PPMM, lysis of intradural adhesions results in an improvement in symptoms in a manner similar to the shunting of PPCM.

Adult↗

PubMed1994

Magnetic resonance imaging of unusual intracranial infections.

We review the etiologic agents, epidemiology, pathogenesis, pathology, clinical manifestations, and imaging features of several unusual intracranial infections that have not been discussed elsewhere in this issue. The central nervous system (CNS) infections discussed are Creutzfeldt-Jakob disease (CrJaD), neurosyphilis, primary amebic meningoencephalitis (PAM), granulomatous amebic encephalitis (GAE), cerebral amebiasis, and cerebral hydatid disease.

Brain↗

PubMed1993

Progressive multifocal leukoencephalopathy in 47 HIV-seropositive patients: neuroimaging with clinical and pathologic correlation.

The authors investigated the spectrum of radiologic findings in a large series (n = 47) of patients seropositive to human immunodeficiency virus (HIV) 1 and with pathologically proved progressive multifocal leukoencephalopathy, to determine the characteristic imaging pattern of the disease. Thirty-six computed tomographic (CT) scans and 29 magnetic resonance (MR) imaging studies obtained in the 47 patients were retrospectively reviewed and correlated with pathologic and clinical findings. Contrast agents were used in 32 CT procedures and 13 MR imaging studies. Lesions typically were hypoattenuating on CT scans and were characterized by areas of increased signal intensity without mass effect on dual-echo MR images. Lesions most often involved periventricular and subcortical white matter in parietooccipital or frontal lobes. Fifteen patients had posterior fossa lesions, and disease was limited to the posterior fossa in two. Lesions were also in the corpus callosum (seven patients), thalamus (eight patients), and basal ganglia (seven patients). In comparison with CT, MR imaging demonstrated greater sensitivity for the extent and number of lesions.

Adolescent↗

PubMed1993

Discrimination of the intravascular lumen and dissections in a single 30-MHz US image: use of "confounding" blood backscatter to advantage.

At 30-MHz intravascular ultrasound, the high-intensity backscatter of blood confounds discrimination of the intravascular lumen from the arterial wall. The authors developed and used a subtraction method to visualize the lumen and dissections through cancellation of backscatter from static areas. In two patients who underwent angioplasty of the superficial femoral artery, the residual hyperechoic pattern created by moving blood allowed good differentiation between the wall and lumen or dissections.

Aged↗

PubMed1993

Asymptomatic and neurologically symptomatic HIV-seropositive subjects: results of long-term MR imaging and clinical follow-up.

Cranial magnetic resonance (MR) images were prospectively obtained in 74 human immunodeficiency virus (HIV)-seropositive subjects, all of whom had undergone MR imaging 24-42 months earlier. The images were interpreted by neuroradiologists blinded to the subject's clinical status and were compared with the initial MR images and clinical findings. Ten subjects had mild neurologic symptoms, with mildly abnormal unchanged images in five (50%). Sixty-four subjects were neurologically asymptomatic, with mildly abnormal images in 13 (20%), most of which remained unchanged. chi 2 analysis revealed a significant difference (P = .042) between the asymptomatic and symptomatic groups with regard to the number of subjects with abnormal follow-up images. The number of abnormal images in the asymptomatic subjects was significantly less than that in the symptomatic subjects. During follow-up of 2-3 1/2 years, most asymptomatic subjects had persistently normal MR images. When abnormal, the imaging abnormalities were usually static and minor.

Adult↗

PubMed1993

Intraluminal vapor bubble induced by excimer laser pulse causes microsecond arterial dilation and invagination leading to extensive wall damage in the rabbit.

BACKGROUND: Previous in vitro studies demonstrated that during excimer laser ablation of aortic tissue in saline, a fast-expanding and imploding vapor bubble is formed. The present in vivo study was designed to demonstrate the formation of a fast-expanding intraluminal bubble in flowing blood and to assess any damage to the adjacent arterial wall. METHODS AND RESULTS: Excimer laser pulses (one to 10, at 55 mJ/mm2 per pulse) were delivered coaxially in the femoral and iliac arteries of nine normal rabbits. Time-resolved flash photography of dissected arteries in situ demonstrated a 50% diameter increase within 75 microseconds after the laser pulse and a subsequent invagination (150-500 microseconds) that corresponded with the temporal course of the bubble expansion (up to 3.2 mm in diameter) and implosion observed in a hemoglobin solution. One day after laser light delivery, light microscopy (47 arterial segments) showed abrasion of the internal elastic lamina, medial necrosis, and extensive dissection planes filled with red blood cells. The degree (up to 100% medial necrosis) and extent of damage (up to 1.9 mm in length) increased with the number of delivered laser pulses. CONCLUSIONS: In blood, each excimer laser pulse generated a fast-expanding and imploding vapor bubble. In vivo, the intraluminal vapor bubble produced microsecond dilation and invagination of the adjacent arterial segment, which induced dissections and extensive wall damage far beyond the penetration depth of 308-nm laser light (< 100 microns). This unique pattern of extensive wall damage observed in the rabbit might explain the mechanism of dissection observed in humans and might have an impact on the acute and chronic outcome after excimer laser coronary angioplasty.

Angioplasty, Laser↗

PubMed1993

Both increased and decreased platelet adhesion to thermally injured subendothelium is caused by denaturation of von Willebrand factor.

BACKGROUND: Thermal angioplasty methods heat the arterial wall. We related platelet adhesion to the temperature to which subendothelium and purified adhesive proteins had been exposed. METHODS AND RESULTS: Cultured subendothelium, purified von Willebrand factor, collagen types I and III, or fibronectin was applied to glass coverslips. Coverslips were mounted on a heating device that applied a temperature gradient from 30 to 100 degrees C. De-endothelialized umbilical arteries were heated by immersion in phosphate-buffered saline. After cooling to room temperature, the surfaces were perfused with blood at 37 degrees C (shear rate, 1600 sec-1). Compared with 37 degrees C, platelet adhesion to endothelial cell matrix was significantly reduced by 25%, 50% or 75% after heating to 69 +/- 1 degree C (mean +/- SEM, P < .05), 72 +/- 1 degree C, or 75 +/- 1 degree C, respectively. Platelet coverage to umbilical artery subendothelium was in the same way significantly reduced after heating to 71 +/- 1 degree C, or 77 +/- 1 degree C, respectively. In contrast to endothelial cell matrix, however, heating to about 55 degrees C increased platelet coverage from 30 +/- 5% to 54 +/- 6% (P < .05). Both platelet adhesion to von Willebrand factor and monoclonal antibody binding against the GpIb binding site of von Willebrand factor showed a comparable temperature dependence as platelet adhesion to subendothelium, provided the proper von Willebrand factor concentration was used. Platelet adhesion to heated collagen types I and III was increased and maximal at 57 +/- 2 degrees C and 62 +/- 2 degrees C, respectively. Preincubation of collagen III with proteins resulted in decreased platelet adhesion with increasing temperatures. Heating did not affect the reactivity of fibronectin. CONCLUSIONS: In vitro platelet adhesion to human subendothelium is reduced by more than 50% after heating it briefly to more than 74 degrees C. Temperatures in excess of 80 degrees C reduce platelet adhesion by at least 85%. Thermal denaturation of von Willebrand factor is responsible not only for the decreased thrombogenicity above 71 degrees C but also for the increased thrombogenicity near 55 degrees C, provided that the von Willebrand factor concentration is low.

Angioplasty, Balloon↗