Sudden Hearing Loss with Vertigo Portends Greater Stroke Risk Than Sudden Hearing Loss or Vertigo Alone

BACKGROUND

Because it is unknown whether sudden hearing loss (SHL) in acute vertigo is a "benign" sign (reflecting ear disease) or a "dangerous" sign (reflecting stroke), we sought to compare long-term stroke risk among patients with (1) "SHL with vertigo," (2) "SHL alone," and (3) "vertigo alone" using a large national health-care database.

METHODS

Patients with first-incident SHL (International Classification of Diseases, Ninth Edition, Clinical Modification [ICD-9-CM] 388.2) or vertigo (ICD-9-CM 386.x, 780.4) were identified from the National Health Insurance Research Database of Taiwan (2002-2009). We defined SHL with vertigo as a vertigo-related diagnosis ±30 days from the index SHL event. SHL without a temporally proximate vertigo diagnosis was considered SHL alone. The vertigo-alone group had no SHL diagnosis. All the patients were followed up until stroke, death, withdrawal from the database, or current end of the database (December 31, 2012) for a minimum period of 3 years. The hazards of stroke were compared across groups.

RESULTS

We studied 218,656 patients (678 SHL with vertigo, 1998 with SHL alone, and 215,980 with vertigo alone). Stroke rates at study end were 5.5% (SHL with vertigo), 3.0% (SHL alone), and 3.9% (vertigo alone). Stroke hazards were higher in SHL with vertigo than in SHL alone (hazard ratio [HR], 1.93; 95% confidence interval [CI], 1.28-2.91) and in vertigo alone (HR, 1.63; 95% CI, 1.18-2.25). Defining a narrower window between SHL and vertigo (±3 days) increased the hazards.

CONCLUSIONS

The combination of SHL plus vertigo in close temporal proximity is associated with increased subsequent stroke risk over SHL alone and vertigo alone. This suggests that SHL in patients with vertigo is not necessarily a benign peripheral vestibular sign.

Metformin Use Correlates with Reduced Risk of Gallstones in Diabetic Patients: A 12-Year Follow-up Study

Objective: Few studies are available on the association between gallstones and metformin use. The objective of the study was to determine whether metformin use is associated with gallstones.

Methods: A population-based retrospective cohort study was conducted using the database of the Taiwan National Health Insurance Program. Subjects of newly diagnosed diabetes mellitus were included from 2002 to 2013. The metformin-exposure group was defined as ≥29 cumulative defined daily dose (DDD) of metformin use. The un-exposure group was defined as <29 cumulative DDD of metformin use. The major endpoint was a new diagnosis of gallstones during the follow-up period. A multivariable Cox proportional hazards regression model was used to evaluate the hazard ratio (HR) and 95% confidence interval (CI) of gallstones associated with metformin use.

Results: After controlling for potential confounders, the adjusted HRs of gallstones were 1.11 (95%CI: 0.84–1.46) for subjects with metformin dosage of 29–180 cumulative DDD, and 0.57 (95%CI: 0.42–0.78) for subjects with metformin dosage >180 cumulative DDD, compared with the un-exposure group.

Conclusion: Long-term use of metformin is associated with reduced risk of gallstones.

Association between different anticholinergic drugs and subsequent dementia risk in patients with diabetes mellitus

BACKGROUND

The effects of oxybutynin, solifenacin and tolterodine on dementia risk in patients with diabetes mellitus (DM) remain unknown. We investigated the effects of oxybutynin, solifenacin and tolterodine on dementia risk in patients with DM.

METHODS

We conducted a cohort study by using the diabetes dataset of the Taiwan National Health Insurance Research Database from 1 January, 2002 to 31 December, 2013. We included 10,938 patients received one type of oxybutynin, solifenacin, or tolterodine, while 564,733 had not. We included a comparable number of patients not receiving oxybutynin, solifenacin, or tolterodine as controls through systematic random sampling matching by age, gender, and the year of the index date with 1 to 1 ratio. The dementia risk was estimated through multivariate Cox proportional hazard regression after adjustment for several confounding factors.

RESULTS

The dementia event rates were 3.9% in the oxybutynin group, 4.3% in the solifenacin group, 2.2% in the tolterodine group and 1.2% in the control group (P<0.001). The adjusted HRs compared to nonusers of anticholinergic drugs were 2.35 (95% CI, 1.96 to 2.81), 2.16 (95% CI, 1.81 to 2.58), and 2.24 (95% CI, 1.85 to 2.73), respectively, for patients receiving oxybutynin, solifenacin, or tolterodine.

CONCLUSION

Our study indicates an association between taking oxybutynin, solifenacin and tolterodine and the subsequent diagnosis of dementia in DM patients. Moreover, the patients using oxybutynin had highest risk. The impact of these three drugs on risk of dementia in non-diabetic populations is warrant.

Benign Paroxysmal Positional Vertigo after Dental Procedures: A Population-Based Case-Control Study

Background

Benign paroxysmal positional vertigo (BPPV), the most common type of vertigo in the general population, is thought to be caused by dislodgement of otoliths from otolithic organs into the semicircular canals. In most cases, however, the cause behind the otolith dislodgement is unknown. Dental procedures, one of the most common medical treatments, are considered to be a possible cause of BPPV, although this has yet to be proven. This study is the first nationwide population-based case-control study conducted to investigate the correlation between BPPV and dental manipulation.

Methods

Patients diagnosed with BPPV between January 1, 2007 and December 31, 2012 were recruited from the National Health Insurance Research Database in Taiwan. We further identified those who had undergone dental procedures within 1 month and within 3 months before the first diagnosis date of BPPV. We also identified the comorbidities of the patients with BPPV, including head trauma, osteoporosis, migraine, hypertension, diabetes, hyperlipidemia and stroke. These variables were then compared to those in age- and gender-matched controls.

Results

In total, 768 patients with BPPV and 1536 age- and gender-matched controls were recruited. In the BPPV group, 9.2% of the patients had undergone dental procedures within 1 month before the diagnosis of BPPV. In contrast, only 5.5% of the controls had undergone dental treatment within 1 month before the date at which they were identified (P = 0.001). After adjustments for demographic factors and comorbidities, recent exposure to dental procedures was positively associated with BPPV (adjusted odds ratio 1.77; 95% confidence interval 1.27–2.47). This association was still significant if we expanded the time period from 1 month to 3 months (adjusted odds ratio 1.77; 95% confidence interval 1.39–2.26).

Conclusions

Our results demonstrated a correlation between dental procedures and BPPV. The specialists who treat patients with BPPV should consider dental procedures to be a risk factor, and dentists should recognize BPPV as a possible complication of dental treatment.

5-alpha-reductase inhibitors and the risk of diabetes mellitus: A nationwide population-based study

BACKGROUND

This nationwide population-based study investigated the risk of type 2 diabetes mellitus (DM) after 5-alpha-reductase inhibitor (5ARI) therapy for benign prostate hyperplasia (BPH) using the National Health Insurance Research Database (NHIRD) in Taiwan.

METHODS

In total, 1,298 adult patients newly diagnosed with BPH and who used more than 28 cumulative defined daily doses (cDDD) of 5ARI were recruited as the therapy group cohort, along with 1,2887 subjects who did not use more than 28 cDDD of 5ARI as a control group from 2002 to 2009. Each patient was monitored for 5 years (from 2003 to 2008) to identify those who subsequently developed type 2 DM. A Cox proportional hazards model was used to compare the risk of type 2 DM between the study and comparison cohorts after adjusting for possible confounding risk factors.

RESULTS

Patients who received 5ARI therapy had a lower cumulative rate of type 2 DM than those who did not receive 5ARI during the five-year follow-up period (3.5% vs. 5.3%, P = 0.003). In sub-group analysis, among the BPH patients aged <65 years, the five-year type 2 DM events hazard ratio (HR) of 5ARI users was lower than that of nonusers (HR: 0.47, 95% confidence interval (CI): 0.24-0.91; P = 0.026).

CONCLUSIONS

Therapy with 5ARI may decrease the five-year risk of type 2 DM in the BPH patients younger than 65 years. Further mechanistic research is warranted to validate the results.

CHADS2 Scores as a Predictor of Ischemic Stroke in Patients With Peripheral Artery Disease

OBJECTIVE

To assess the predictive value of CHADS2 (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke) scores for stroke risk in patients with peripheral artery disease (PAD).

PATIENTS AND METHODS

From Taiwan's National Health Insurance Research Database, we identified a total of 479 participants with non-atrial fibrillation PAD diagnoses recorded from January 1, 2002, through December 31, 2009. The CHADS2 score was used to stratify 5-year ischemic stroke risk. All participants were followed up from the date of enrollment until ischemic stroke event, death, or the end of 2009.

RESULTS

The 5-year risk of ischemic stroke in the present study was 9.4%. A strong correlation was found between the PAD and CHADS2 score (CHADS2 score of 0-1, 0.4%; CHADS2 score of 2-3, 12.3%; CHADS2 score ≥4, 84.0%; area under the curve = 0.920). After adjustment, CHADS2 score was found to be positively correlated with increased risk of ischemic stroke.

CONCLUSIONS

Our results indicate that patients with PAD have a significantly higher risk of ischemic stroke and that the CHADS2 score can be used as an indicator of risk for ischemic stroke. Cardiovascular risk evaluation and management are suggested for patients with PAD and higher CHADS2 scores.

A retrospective analysis of the factors associated with hypercalcaemia in patients with advanced cancer

Hypercalcaemia, a common complication of advanced cancer, causes multiple clinical symptoms, deteriorates patients' quality of life, and is associated with poor prognoses. This study aimed to identify the factors that may be associated with hypercalcaemia in advanced cancer by retrospectively reviewing the medical records of patients (n = 404) admitted to the palliative ward of the Kaohsiung Medical University Hospital, Taiwan, from 2006 to 2008. Patients' demographics, clinical data and symptoms were recorded. Seventy-nine of 404 patients had hypercalcaemia (19.6%), predominant in cases of head-and-neck cancer and haematological malignancies (P < 0.05), but not in those of bone metastases. Hypercalcaemia was associated with consciousness disturbances and leucocytosis (P < 0.05). We recommend that ionised (corrected) calcium levels be monitored clinically in patients with advanced cancer especially when consciousness disturbances are noted, or when head-and-neck or haematological malignancies are present. Testing of free calcium levels is also recommended in patients with leucocytosis.

Lifetime exposure to cigarette smoking and the development of adult-onset atopic dermatitis

BACKGROUND

Adult-onset atopic dermatitis (AD) has recently been recognized as a distinct disease entity, but its risk factors have not yet been clearly defined. Although gestational and perinatal exposure to tobacco smoking may be associated with the development of classic AD, the association between active/passive smoking and adult-onset AD remains controversial.

OBJECTIVES

To determine if exposure to smoking, including environmental tobacco smoke (ETS), is associated with the risk of adult-onset AD.

METHODS

Tobacco smoking and exposure to ETS were measured in a case-control association analysis in 83 patients with physician-diagnosed adult-onset AD and 142 age- and sex-matched controls.

RESULTS

Multiple logistic regression analyses showed that, among the potential environmental risk factors, both current and ever smoking were significant risk factors for adult-onset AD [odds ratio (OR) 4·994 and 3·619, respectively], compared with never smoking. Also, packs per year was significantly associated with adult-onset AD (OR 1·058, 95% confidence interval 1·028-1·089), suggesting a lifelong cumulative risk in current smokers. Moreover, nonsmokers with adult-onset AD reported significantly more exposure to ETS.

CONCLUSIONS

Early and/or current exposure to cigarette smoking may contribute cumulatively to the development of adult-onset AD. Exposure to ETS in childhood is associated with the development of adult-onset AD. Adults should be discouraged from smoking to prevent adult-onset AD in themselves and their family members.

Bilateral Video-Assisted Thoracoscopic Thymectomy vs. Extended Transsternal Thymectomy in Myasthenia Gravis: A Prospective Study

The optimal approach to thymectomy remains controversial. This study is designed to prospectively compare the results between bilateral video-assisted thoracoscopic thymectomy (BVTx) and extended transsternal thymectomy (ETTx) in patients with myasthenia gravis (MG) without thymoma. Fifteen patients who had undergone BVTx and 16 patients who had undergone ETTx were compared for age, gender, severity of disease, preoperative duration of disease, operative time, intraoperative blood loss, postoperative complications, hospital stay, duration of chest tube drainage, thymic histopathology, pain perception by visual analog scale (VAS), remission and improvement rate, period of follow-up, and activities of daily living (ADL). Fisher's exact test, t test and paired t test were used for statistical analysis. BVTx had longer operative time and less intraoperative blood loss than that of the ETTx. Their remission rates and their degree of postoperative ADL improvement were not significantly different. However, the lowering of VAS was significantly greater in the sternotomy group at 3 months. All other parameters were not significantly different. No mortality was noted in the series. We consider BVTx as an effective alternative procedure to the transsternal approach for patients with nonthymomatous MG. As more and more people care about cosmetics, BVTx could become the future trend.

Interrelations of lead levels in bone, venous blood, and umbilical cord blood with exogenous lead exposure through maternal plasma lead in peripartum women

Recent research has raised the possibility that fetal lead exposure is not estimated adequately by measuring lead content in maternal whole blood lead because of the variable partitioning of lead in whole blood between plasma and red blood cells. Lead in maternal plasma may derive in large part from maternal bone lead stores. In this study we aimed to estimate the contribution of maternal whole blood lead, maternal bone lead levels, and environmental lead to umbilical cord blood lead levels (as a measure of fetal lead exposure). In the model, we assumed that lead from all of these sources reaches the fetus through the maternal plasma lead pathway. In 1994-1995, we recruited 615 pregnant women for a study of lead exposure and reproductive outcomes in Mexico City. We gathered maternal and umbilical cord blood samples within 12 hr of each infant's delivery and measured maternal lead levels in cortical bone and trabecular bone by a K-X-ray fluorescence (K-XRF) instrument within 1 month after delivery. We administered a questionnaire to assess use of lead-glazed ceramics (LGC) to cook food and we obtained data on regional air lead levels during the 2 months before delivery. We used structural equation models (SEMs) to estimate plasma lead as the unmeasured (latent) variable and to quantify the interrelations of plasma lead, the other lead biomarkers, and environmental lead exposure. In the SEM analysis, a model that allowed plasma lead to vary freely from whole blood lead explained the variance of cord blood lead (as reflected by a total model R(2); R(2) = 0.79) better than did a model without plasma lead (r(2) = 0.67). Cortical bone lead, trabecular bone lead, use of LGC, and mean air lead level contributed significantly to plasma lead. The exchange of lead between plasma and red blood cells was mostly in the direction of plasma to cells. According to the final model, an increase in trabecular bone lead and cortical bone lead was associated with increases in cord blood lead of 0.65 and 0.25 microg/dL, respectively. An increase of 0.1 microg/m(3) in air lead was associated with an increase in the mean level of fetal cord blood lead by 0.67 microg/dL. With one additional day of LCG use per week in the peripartum period, the mean fetal blood lead level increased by 0.27 microg/dL. Our analyses suggested that maternal plasma lead varies independently from maternal whole blood lead and that the greatest influences on maternal plasma lead are maternal bone lead stores, air lead exposures, and recent cooking with LGC. The contributions from endogenous (bone) and exogenous (environmental) sources were relatively equal. Measurement of plasma and bone lead may be important in accurately assessing fetal lead exposure and its major sources, particularly if exogenous exposures decline.

Adverse health effects among household waste collectors in Taiwan

Household waste collectors (HWCs) are potentially exposed to a variety of bioaerosols and toxic materials. Collection of household waste is also a job which requires repeated heavy physical activity such as lifting, carrying, pulling, and pushing. The object of this study was to assess whether there is an excess of adverse health outcomes among HWCs. The subjects were all current employees of the Household Waste Collection Department in the County of Kaohsiung, Taiwan. The survey questionnaire was completed by 533 HWCs and 320 office workers. Our data indicate that household waste collection presents a risk for the development of chronic respiratory symptoms (cough, phlegm, wheezing, and chronic bronchitis), musculoskeletal symptoms (low back pain and elbow/wrist pain), and injuries caused by sharp objects.

An unusual case of organophosphate intoxication of a worker in a plastic bottle recycling plant: an important reminder

A young man was sent to our emergency unit because he had suffered from vomiting and cold sweating for 2 days. At the time he was admitted, he had no acute abdominal pains or gastrointestinal symptoms, and a physical examination revealed nothing but a faster heart rate and moist, flushing skin. The patient had worked for 6 years at a plastic bottle-recycling factory, but none of his co-workers had the same symptoms. Nevertheless, because the plant also recycled pesticide bottles, we suspected organophosphate pesticide intoxication. The patient's plasma acetylcholinesterase level was checked, revealing 1498.6 microU/L (normal range: 2,000-5, 000) on the first day and 1,379 microU/L on the second day. Upon questioning, the patient recalled that one of his shoe soles had been damaged and that his foot had been wet from walking all day in rain collected on the factory floor on the day that his symptoms first occurred. We conducted a study in the change of preshift and postshift acetylcholinesterase levels among six of his co-workers on a rainy day. We used the Wilcoxon signed rank test to compare the preshift and postshift plasma acetylcholinesterase levels; no significant difference was revealed (p = 0.600), leaving contamination via the damaged shoe sole suspect. We reviewed the literature on organophosphate intoxication; pesticide bottle-recycling factories were reported to be at a low risk of organophosphate toxicity in the working environment. However, because the potential risk of intoxication is still present, protective equipment such as clothing, gloves, and water-proof shoes should be worn, and employees should be educated on the potential risks.

Vibration perception thresholds in workers with long term exposure to lead

OBJECTIVES

To evaluate the impact of long term occupational exposure to lead on function of the peripheral nervous system as reflected by vibration perception threshold (VPT), measured with a portable vibrameter.

METHODS

217 Workers in a lead battery factory were required to have an annual blood lead measurement during each of the 5 years preceding this study. All were invited to take the VPT test. A total of 206 workers were studied. The associations were analysed between VPTs and current blood lead concentration, mean concentration of blood lead over the past 5 years, maximum blood lead concentration during the past 5 years, index of cumulative blood lead (ICL), time weighted index of cumulative blood lead (TWICL), and percentage of lifespan spent at work in the plant, as well as the other potential confounders. Ordinary multiple regressions, generalised additive models, and hockey stick regression analyses were used to explore the potential existence of a threshold effect of blood lead variables on VPT.

RESULTS

VPT at a frequency of 220 Hz ranged from 6 to 100 (10(-2) g, or 0.098 m/s(2)) with a mean (SD) of 19.8 (14.2) for the feet and from 4 to 43 with a mean (SD) of 10.2 (6.1) for the hands. The five variables of exposure to lead were all significantly correlated with VPT of the feet but not the hands. In multiple linear regression analyses, the mean of the blood lead concentrations and the TWICL were significantly associated with VPT of the feet. The relation between VPT of the feet and mean blood lead was shown to be a J shaped curve with a generalised additive model and local smoothing technique. In the hockey stick regression, evidence was found of a threshold effect at a mean blood lead concentration of 31 microgram/dl. Above this threshold it was estimated that each increase of 1 microgram/dl mean blood lead over 5 years would increase VPT of the feet by 0.29 (10(-2) g) or 0.028 m/s(2) (at a frequency of 220 Hz) with other potential confounders held constant.

CONCLUSION

This study suggests that measurement of vibration sensory threshold is a relatively effective tool for detecting lead neuropathy in field studies, and that lead might cause sensory neuropathy with an effect threshold corresponding to a 5 year mean blood lead concentration of 31 microgram/dl.

Adolescent hyperactivity and general psychopathology

The aim of this study was to explore the relationship between activity and psychopathology in adolescents. A total of 289 high school students completed the Symptom Check List-90-R (SCL-90-R) and Wender Utah Rating Scale (WURS) in December 1998. The WURS was used to measure the students' activity level and the SCL-90-R was used as a measure of general psychopathology. Forty-one students (14.18%) scored higher than 46, the cut-off point for differentiation of attention deficit hyperactivity disorder (ADHD) from the general population according to Ward's report, in the WURS (WURS(+)). The WURS(+) students scored significantly higher than the WURS(-) students in all the subscales of SCL-90-R. The prevalence rate of adolescent WURS(+) in this study is 14.18%. This result shows that ADHD adolescents have overlapping symptoms with depression.

Relationship of blood lead levels to personal hygiene habits in lead battery workers: Taiwan, 1991-1997

BACKGROUND

The blood lead concentrations of workers in lead battery factories are more than 4 times higher than those of the general population in Taiwan. Therefore, efforts are needed to reduce lead exposure in this high-risk population. A health promotion program on personal habits that reduce lead exposure has been carried out in a lead battery factory since 1991. This study investigated the longitudinal relationship of workers' blood lead concentrations and personal hygiene habits from 1991 through 1997.

METHODS

In each of the 7 years of the study, occupational physicians questioned workers regarding nine personal hygiene items, personal information, and medical history before their annual health examination. The relationship between blood lead concentrations and personal hygiene habits was analyzed by longitudinal multiple regression in a mixed effect model with adjustment for potential confounders. In addition, the risk ratio of a blood lead concentration exceeding 40 micrograms/dL in men and 30 micrograms/dL in women (the action levels set by the Department of Health, Taiwan) was estimated by generalized estimating equations.

RESULTS

Blood lead levels decreased significantly in the first 5 years of the study. The personal habits most closely related to blood lead concentrations were smoking at work sites (estimated coefficient = 3.13, P < 0.001), and eating at work sites (estimated coefficient = 1.38, P = 0.069). The risk ratio for workers with both these habits exceeding the action level of blood lead was 2.93 (95% CI 1.27-6.77). Difference in job titles, however, accounted for a major portion of the variance in blood lead. For example, working in "pasting" and "plate-cutting" was associated with blood lead elevations > 20 micrograms/dL in comparison to the "low- or no-exposure jobs."

CONCLUSIONS

Health promotion programs can decrease exposure of lead workers; reducing the practices of smoking and eating at work sites should be the core of such programs. However, a major reduction in lead exposure for some jobs (e.g., "pasting" and "plate cutting") in lead battery factories in Taiwan is unlikely to occur without major engineering changes.

Latex agglutination test for detection of antibodies to Toxoplasma gondii

A resurgence of interest in Toxoplasma gondii has occurred because this coccidian parasite causes lethal infections in immunologically compromised hosts and is responsible for at least 3,000 congenitally infected infants in the United States annually. Thus, rapid, specific, and inexpensive serologic tests are required for routine screening of patients, especially pregnant women. We have developed a latex agglutination test for antibodies to T. gondii which utilizes covalently coupled T. gondii antigens. When compared with an indirect immunofluorescence assay, the latex test had a sensitivity of 94% and specificity of 100%. Compared with an enzyme-linked immunosorbent assay, the latex test had 86% sensitivity and 100% specificity. When testing samples which exhibited nonspecific polar staining by the immunofluorescence assay, the enzyme-linked immunosorbent assay had a 50% false-positive rate, whereas the latex agglutination test yielded no false-positive results. Thus, the latex agglutination test provided an efficacious method for routine serological screening for antibodies to T. gondii.

Immunochemical detection by specific antibody to thrombin of prothrombin conformational changes upon adsorption to artificial surfaces

Polyclonal antihuman alpha-thrombin antibodies produced in rabbits reacted minimally (less than 0.05%) in solution with human prothrombin. However, when prothrombin was adsorbed to artificial surfaces such as polyvinyl chloride (PVC), the cross-reactivity of surface-bound prothrombin with antibody IgG to thrombin (greater than 95% purity) was shown to be significantly enhanced. On PVC, the molar ratios of antibody IgG to thrombin/prothrombin approached the same level as that of antibody IgG to thrombin/thrombin when thrombin was adsorbed to the same material. The analyses of antigen-antibodies interaction, in solution with a direct binding assay by immune precipitation at high-speed centrifugation (160,000 g, 30 min), and on solid-phase PVC, were accomplished by use of double-labeling technique, i.e., 131I-thrombin (or 131I-prothrombin) and 125I-antibody IgG to thrombin. The results appear to suggest that prothrombin adsorption to PVC has resulted in some molecular conformational changes so that immunologically the adsorbed prothrombin resembles that of adsorbed thrombin on the same PVC surface.

Adsorption and reactivity of human prothrombin to artificial surfaces

Human prothrombin in Tyrode's solution, in mock plasma (albumin, fibrinogen, and IgG mixture), and in citrated plasma adsorbs to Cuprophane, polyvinylchloride, and polyacrylonitrile surfaces. The adsorption of prothrombin is maximal in Tyrode's solution and minimal in plasma. The surface concentrations of prothrombin are highest on polyacrylonitrile, second on polyvinylchloride, and lowest on Cuprophane at all prothrombin concentrations tested in the bulk solution. Qualitative tests show that prothrombin adsorbed to polyvinylchloride can be activated by Taipan snake venom to generate thrombin that clots fibrinogen. However, more quantitative tests indicate that only part of the adsorbed prothrombin on all three materials can be activated to form thrombin exhibiting amidolytic activity. The partial reactivity of adsorbed prothrombin is further confirmed by release of 125I-peptide from surface bound 125I-prothrombin after treatment with Australian Taipan snake venom. Prothrombin bound to Cuprophane seems to promote granulocyte adhesion, but has no effect on platelet adhesion.

In situ immunoradiometric assay of fibrinogen adsorbed to artificial surfaces

An in situ immunoradiometric assay was devised to quantitate human fibrinogen deposited on hemodialysis membrane, Cuprophane, from in vitro exposure to fibrinogen solution and from ex vivo extracorporally clinical use. The method requires a monospecific 125I-labeled antifibrinogen -IgG purified by DEAE chromatography and immunoadsorption. The labeled antifibrinogen IgG was shown to react specifically with fibrinogen adsorbed and immobilized (by glutaraldehyde) on Cuprophane. Other plasma proteins such as human albumin, IgG, or alpha-thrombin, adsorbed singly or coadsorbed with fibrinogen on the surface did not seem to affect the fibrinogen- antifibrinogen reaction. The presence of blood cells such as platelets and granulocytes with fibrinogen on Cuprophane reduced only slightly the uptake of 125I- antifibrinogen -IgG. The examination of fibrinogen-fibrin deposition on clinically used Cuprophane by this technique and by autoradiography of the same material following 125I- antifibrinogen -IgG conjugation indicated that the deposition of fibrinogen was heavy and heterogeneous. We concluded that this in situ method may be useful to monitor fibrinogen-fibrin deposition and adsorption of other plasma proteins that occur under in vitro, ex vivo, and in vivo conditions.

Adsorption and reactivity of human fibrinogen and immunoglobulin G on two types of hemodialysis membranes

Phase contrast microscopic examination of Cuprophane and polyacrylonitrile. After clinical ex vivo use by uremic patients revealed extensive cellular deposition of erythrocytes, platelets, and leukocytes on Cuprophane but not on polyacrylonitrile. In vitro studies with 125I-labeled human fibrinogen or immunoglobulin G (IgG) showed that the adsorption of fibrinogen or IgG was greater on polyacrylonitrile than on Cuprophane. Further studies on the reactivity of fibrinogen adsorbed on polyacrylonitrile surface indicated that the absorbed fibrinogen: (a) was not desorbed readily from the surface, (b) was not appreciably displaced by other plasma proteins such as albumin, IgG, and fibrinogen, (c) was not readily accessible for reaction with 125I-antifibrinogen-IgG, and (d) did not promote the adhesion of 51Cr-labeled platelets. IgG adsorbed on the surface produced essentially no effect on platelet adhesion to polyacrylonitrile and promoted only slightly on the adhesion of granulocytes to the same material. On the other hand, fibrinogen and IgG augmented greatly the platelet adhesion to Cuprophane and IgG enhanced the granulocyte adhesion moderately. These data indicate that fibrinogen and IgG, though at high concentration on polyacrylonitrile, may adsorb in a biologically inactive form. Our observations suggest that the thrombogenicity of an artificial surface may not be assessed entirely by the types and amount of the various protein species adsorbed but is likely determined by the reactivity of the specific protein species adsorbed on the material.

Albumin-IgG complexes in human serum and plasma that inhibit blood platelet adhesion

Macromolecular albumin-IgG complexes have been isolated from human serum and characterized immunologically. These complexes are shown to be present in plasma also and appear to be normal constituents of blood. The complexes can be demonstrated in normal serum and plasma by immunoelectrophoresis and rocket immunoelectrophoresis, as well as by use of a two-step radioimmunologic binding test. The albumin-IgG complexes inhibit adhesion of human platelets to glass and account for 12-16% of the total protein in serum.

Effects of heparin on platelet aggregation and release and thromboxane A2 production

Heparin, when added to citrated platelet-rich plasma (PRP), caused potentiation of platelet aggregation and the release reaction induced by the aggregating agents adenosine diphosphate (ADP), arachidonic acid, collagen, and epinephrine. At low concentrations (4.7 x 10(-5) M) arachidonic acid failed to cause aggregation of platelets in citrated PRP. However, in the presence of heparin, the same concentration of arachidonic acid caused aggregation. Examination of PRP for the presence of thromboxane A2 (TxA2) by use of a bioassay revealed that heparin also stimulated release of TxA2. This finding indicated that platelets released more TxA2 when they were challenged by low concentrations of arachidonic acid in the presence of heparin than in its absence. Platelets were labeled with 3H-arachidonic acid and 14C-serotonin, and attempts were made to determine whether heparin stimulated the platelet release reaction first with subsequent increased production of TxA2, or alternatively, whether heparin stimulated TxA2 production first with subsequent enhancement of the release reaction. In view of the demonstrated simultaneous release of 14C-serotonin and 3H-arachidonic acid metabolites, it appeared that either release of 14C and 3H occurs concurrently or, even if one of these events is dependent on the other, both events take place in rapid succession. Timed sequential studies revealed that in the presence of arachidonic acid, the addition of heparin hastened the apparently simultaneous release of both 14C and 3H.

Interaction of plasma proteins with artificial surfaces: protein adsorption isotherms

A simple technique using a small disc which is dipped into a 125I-labeled protein solution has been devised to study the adsorption of human albumin, fibrinogen, and IgG onto Cuprophane or PVC. The purity of these human plasma proteins has been examined carefully with PAGE and immunochemical methods. The adsorption isotherms of albumin, fibrinogen, and IgG show a langmuir type adsorption. Delipidation of albumin did not alter the albumin affinity to Cuprophane and PVC. The surface saturation concentration (ng/cm2) for albumin, fibrinogen, or IgG were all found to be more on PVC (a hydrophobic surface) than on Cuprophane (a hydrophilic surface). The competitive adsorption of one protein species in a two- or three-protein mixture was also studied. Albumin and fibrinogen complete with each other for adsorption. The effects of IgG on the adsorption of albumin or fibrinogen were inconsistent and not predictable; the reason for this is unknown. The effect of laminar flow on albumin adsorption was studied with a specially designed Richardson flow chamber. In general caused an increase in albumin adsorption over that at static conditions. The increase of albumin adsorption was more pronounced also for PVC than for Cuprophane from 1 to 10 ml/min.

Affinity chromatographic demonstration of a thrombin binding protein from the platelet plasma membrane

Human platelet plasma membrane glycoprotein I with an apparent molecular weight of approximately 150,000 has been shown to be one of the proteins retained by thrombin immobilized on Sepharose 4B. The retained glycoprotein has been recovered by sodium dodecyl sulfate elution and characterized by SDS polyacrylamide gel electrophoresis in the presence of 2-mercaptoethanol.

A concise method for study of the binding of thrombin to human platelets

A rapid and sensitive technique is described for use in the study of the binding of 125I-thrombin to human platelets. The procedure involves the separation of free thrombin from platelet-bound thrombin by passage of this mixture through a discontinuous sucrose density gradient at low centrifugal force (1,500xg). Results obtained by this method are shown to be comparably to data obtained by two other conventional methods. This technique may facilitate further kinetic study of the binding of thrombin to human platelets.

The endothelium: roles in thrombosis and hemostasis

The renewed interest in endothelial function is based partly on success with tissue culture of endothelial cells. Endothelium functions primarily in the control of blood vessel wall permeability and in the provision of a blood-compatible lining surface. Recent findings indicate that endothelial cells are active metabolically in ways that may help prevent thrombosis. Endothelium actively degrades several different vasoactive compounds that circulate in blood and that can serve as platelet-aggregating agents. Endothelium also contains an inhibitor of platelet function and an activator of plasminogen, both of which can be released from the cell in response to appropriate stimuli. While intact endothelium functions primarily in prevention of thrombosis, damaged endothelium can contribute greatly to thrombus formation. Release of prostaglandins, adenine nucleotides, and other intracellular components from damaged endothelium can enhance platelet aggregation. Damaged endothelium may not function effectively in removal of vasoactive agents and may not release effective quantities of the inhibitor of platelet function or the activator of plasminogen. Altered endothelium exhibits tissue-factor activity, which can activate the extrinsic blood coagulation-system cascade. Finally, altered endothelial cells may contract and expose basement membrane to blood, thus enhancing thrombosis.

Multiple active forms of thrombin: binding to platelets and effects on platelet function

The effect of various forms of thrombin on certain platelet functions has been investigated. Partially purified bovine thrombin which is a mixture of multiple active forms of thrombin, was chromatographed to yield molecular species termed alpha-, beta-, and gamma-thrombin, each of which has varying degrees of fibrinogen clotting and esterase activities. A direct correlation was observed between the ability of the different forms of thrombin to clot fibrinogen and to influence platelet function. In general, thrombin with high fibrinogen clotting activity was also a potent inducer of platelet aggregation and the release reaction, while those species with low clotting ability were poor inducers of aggregation and release.

The subcellular distribution and partial characterization of cholinesterase activities of canine platelets

The multiple cholinesterase activities in canine platelets have been investigated. Platelets were homogenized by rapid decompression under nitrogen, glass tube/Teflon pestle, and glycerol lysis techniques. Rapid decompression under nitrogen technique was found to be the most efficient and gentle method for cell disruption. Homogenates were subfractionated using sodium diatrizoate density gradients. Marker enzyme assays and pulse labeling experiments with 5-hydroxyl[14C] tryptamine and [125I] thrombin on prepared subcellular fractions confirmed that the soluble, plasma membrane and the granule-1 fractions were all in reasonably pure form. Furthermore, labeling of the plasma membrane with [125I] thrombin is cited as the first successful attempt at attaining significantly bound marker for this structure. Cholinesterase activity distributions measured in these fractions indicated that about 30% of the activity was present in the plasma membrane, 50% in granule-1 and 5% in soluble fractions. Kinetic data of cholinesterase activities obtained from intact platelets, plasma membrane preparations and platelet release supernatants indicated that they are strikingly similar.

Adhesion of human blood platelets to glass polymer surfaces. II. Demonstration of the presence of a natural platelet adhesion inhibitor in plasma and serum

Adhesiveness of washed platelets resuspended in citrated plasma, serum, or several different media has been investigated. A method specific for quanititation of adhesion was used. Platelets suspended in saline of Tyrode's solution were found to be highly adhesive to glass, polyethylene, polyvinyl chloride, or Cuprophane. This adhesiveness of platelets to test surfaces decreased by nearly 50% when plasma was the suspension medium. When the suspension medium was serum, the decrease in adhesion was nearly 75%. Cohn fraction V also decreased the adhesiveness of platelets significantly, but highly purfied albumin had only a small effect. Several pharmacologic agents decreased platelet adhesiveness when added to platelets suspended in plasma or serum, but had negligible effect on the adhesiveness of platelets suspended in artificial media devoid of proteins. Normal washed platelets, when suspended in citrated plasma obtained from an afibrinogenemic donor or in normal serum, showed a significant decrease in adhesion compared to the same platelets suspended in normal citrated plasma. Addition of fibrinogen to afibrinogenemic plasma or normal serum restored the adhesiveness of platelets to normal levels. Normal platelets resuspended in plasma obtained from a thrombasthenic donor exhibited normal adhesiveness. These observations suggested that while fibrinogen promotes platelet adhesion, plasma or serum possess also an adhesion-inhibiting activity.