The spectrum of haemostatic characteristics of women with unexplained menorrhagia.

While an estimated 13% of women with unexplained menorrhagia have von Willebrand disease (VWD), the frequency of other potential bleeding disorders has been uncertain. This study describes the relatively wide range of laboratory characteristics of women with unexplained menorrhagia and presents issues affecting diagnosis in this population. Women with pictorial blood assessment chart (PBAC) score > 100 were identified at six U.S. sites and asked to remain drug free for 10 days prior to testing. Blood was collected on one of the first four menstrual cycle days and tested at a central laboratory for procoagulant factors, VWD and fibrinolytic factors. Platelet function testing by PFA-100® (PFA) and platelet aggregation with ATP release (PAGG/ATPR) were performed locally using standardized methods. Among 232 subjects, a laboratory abnormality was found in 170 (73.3%), including 124 of 182 White (68.1%) and 34 of 37 Black (91.9%) subjects; 6.0% had VWD, 56.0% had abnormal PAGG/ATPR, 4.7% had a non-VWD coagulation defect (NVCD) and 6.5% had an abnormal PFA only. AGG/ATPR was reduced in 58.9% of subjects, with multiple agonists in 28.6%, a single agonist in 6.1% and ristocetin alone in 24.2%. Frequencies of PAGG/ATPR defects varied by study site and race; frequencies of VWD and NVCD were similar. Laboratory abnormalities of haemostasis, especially platelet function defects, were common among women with unexplained menorrhagia across multiple U.S. sites. To what degree these abnormalities are clinically significant requires further study.

[Rupture of the interventricular septum after the blunt trauma of thorax]. / Traumatická ruptura mezikomorového septa jako následek tupého poranení hrudníku--kazuistika.

Authors present the case of little patient with the dissection, pseudoaneurysm and finally a rupture of the interventricular septum after the blunt thracic injury. The patient was smitten as a pedestrian by a car and during the whole period of her stay in the hospital she was showing signs of circulatory instability. Due to the current intraabdominal injuries this circulatory decompensation was first assigned to hemoperitoneum, for which the girl was operated on about 3 hours after admission. Nevertheless, even after the abdminal cavity check, after the treatment of supreficial liver lacerations and intensive volume resuscitation the patient showed signs of insufficiency. Diagnosis was finally determined on the base of the transthoracic echocardiography (TTE), which proved the traumatic rupture of interventricular septum. The operation followed correcting the defect, which was performed with a good result according to the TTE postoperatively. Nevertheless, 27 hours after the admission the patient died due to the electromechanical dissociation. In the discussion the authors then evoke a number of papers concerning the same topic.

Intracardiac thrombus--a rare complication of the steroid resistant nephrotic syndrome.

BACKGROUND: An intracardiac thrombus is extremely rare in children with the nephrotic syndrome (NS). OBJECTIVES: To present a case report of a child with steroid resistant NS and intracardiac thrombus. METHODS AND RESULTS: A 3.5-year-old boy with the first attack of steroid resistant NS was admitted to the hospital. A histological evaluation of the renal biopsy specimen revealed the minimal changes disease (MCD). There were no mutations in the podocin gene. The treatment with furosemide, albumin, prednisone, metylprednisolone, cyclophosphamide, enalapril and losartan was ineffective, as the intermittent oedema, proteinuria, hypoalbuminemia and hypercholesterolemia were still present. 8 weeks after the disease onset, the sinus tachycardia occurred and the echocardiography revealed a thrombus in the right ventricle, which had gradually proceeded to the pulmonary artery bifurcation. The thrombolysis with 40 mg of alteplase was initiated. Two hours after the alteplase application, the thrombus was not detectable. The mutational analysis of factors V, II and MFTHR genes were negative. The repeated echocardiography performed after 1 week, 2 and 6 months, respectively, revealed a normal cardiac function and morphology. The patient received prophylactic doses of fraxiparin for 3.5 months followed by warfarin. A remission of the nephrotic syndrome was achieved with high doses of cyclosporine A together with atorvastatin at 7 month after the disease onset. CONCLUSION: The thromboembolism as a result of the hypercoagulation status is a serious complication of the nephrotic syndrome. The intracardiac localisation of thrombus is extremely rare (Fig. 2, Ref. 10). Full Text (Free, PDF) www.bmj.sk.

[Invasive streptococcal infections]. / Invazivní streptokokové infekce.

The severity of streptococcal infections depends upon different virulence of individual strains of its causative agent. The most important species are beta-haemolytic group A streptococci (GAS). Clinical manifestations include skin affections, respiratory tract infections and, in particular, serious systemic invasive infections. The pathogenicity of GAS is derived from cell wall components and extracellular products, especially toxins with properties of the so-called superantigens. Less invasive forms of the disease are include necrotizing fasciitis, myositis, pneumonia, sepsis without focus, arthritis, meningitis, puerperal sepsis, streptococcal toxic shock syndrome (STSS) and severe course of erysipelas and cellulitis with blood culture positive for GAS. In most cases, soft tissue infections dominate, often accompanied by chronic diseases of lower extremities in elderly patients. The other clinical forms are rather rare. In children, the condition is clearly frequently related to chickenpox. The generally accepted therapeutic management comprises comprehensive intensive care, early administration of penicillin in combination with clindamycin, and surgical intervention. The use of intravenous immunoglobulins (IVIG), elimination methods and hyperbaric oxygen are under discussion. The slight increase in cases and ineffective prevention require rapid assessment of diagnosis and adequate treatment as a protracted course of the condition is connected with a high mortality rate.

The risk of stroke and death in patients with aortic and mitral valve endocarditis.

BACKGROUND: Previous studies have generated inconsistent results when attempting to define predictors of stroke and death in patients with endocarditis. We sought to examine the relationship between vegetation 2-dimensional size and stroke in those with infective endocarditis (IE) and to identify differences between aortic valve (AV) and mitral valve (MV) IE with regard to clinical characteristics, echocardiographic findings, stroke, and death. METHODS: We used the Duke Endocarditis Database to examine 145 episodes of definite IE involving the AV, n = 62, or MV, n = 83. A logistic regression model was developed to analyze important variables in predicting stroke, and a Cox proportional hazards model was used in predicting mortality. RESULTS: The mitral valve was infected in 57% of the cases. Vegetations were more commonly detected in patients with MV IE (92.8% vs 66.1%, P =.001) and these MV vegetations were significantly larger (P <.05). Thirty-four of 145 episodes (23.4%) were complicated by stroke. MV IE was associated with a greater stroke rate, 32.5% versus 11.3% (P =.003). Strokes tended to occur early in the course of illness, particularly in MV IE. In the multivariable model, the independent predictors of stroke were MV IE (P =.04) and vegetation length (P =.03). Independent predictors of 1-year mortality were age (P =.02) and vegetation area (P =.048). CONCLUSION: Stroke is more common in patients with MV IE. Vegetation 2-dimensional size and characteristics are important predictors of stroke and mortality. These findings may lead to predictive models that allow physicians to identify high-risk patients who need aggressive treatment strategies to prevent long-term morbidity and mortality.

Development of a wireless system for auditory neuroscience.

In order to study how the auditory cortex extracts communication sounds in a realistic acoustic environment, a wireless system is being developed that will transmit acoustic as well as neural signals. The miniature transmitter will be capable of transmitting two acoustic signals with 37.5 KHz bandwidths (75 KHz sample rate) and 56 neural signals with bandwidths of 9.375 KHz (18.75 KHz sample rate). These signals will be time-division multiplexed into one high bandwidth signal with a 1.2 MHz sample rate. This high bandwidth signal will then be frequency modulated onto a 2.4 GHz carrier, which resides in the industrial, scientic, and medical (ISM) band that is designed for low-power short-range wireless applications. On the receiver side, the signal will be demodulated from the 2.4 GHz carrier and then digitized by an analog-to-digital (A/D) converter. The acoustic and neural signals will be digitally demultiplexed from the multiplexed signal into their respective channels. Oversampling (20 MHz) will allow the reconstruction of the multiplexing clock by a digital signal processor (DSP) that will perform frame and bit synchronization. A frame is a subset of the signal that contains all the channels and several channels tied high and low will signal the start of a frame. This technological development will bring two benefits to auditory neuroscience. It will allow simultaneous recording of many neurons that will permit studies of population codes. It will also allow neural functions to be determined in higher auditory areas by correlating neural and acoustic signals without apriori knowledge of the necessary stimuli.

Evaluation of the Contribution of CAS in Combination with the Subcranial/Subfrontal Approach in Anterior Skull Base Surgery.

In this study, 31 cases with different anterior skull base lesions mandating broad exposure, including the sphenoidal, parasellar, and clival region, were surgically treated using the frameless computer assisted surgery (CAS) system. The contribution of navigated surgery in relation to the broad exposure and direct visualization of this region rendered by the subcranial-subfrontal approach was evaluated. In group I, consisting of extensive tumors, the contribution of CAS was only given in five cases for the exposure of the tumor extensions located to the parasellar sphenoclival complex with concomitant distortion of the anatomic landmarks. No advantages were experienced in the more anterior locations along the ethmoidal compartment and frontal sinus. In the cases in group II, consisting of congenital anomaly implying fronto-orbital advancement and a meningoencephalocele as well as extensive mucoceles, the CAS was only helpful in those cases with an extremely aberrative anatomy in these regions.

[Results and role of carotid endarterectomy]. / Ergebnisse und Stellenwert der Karotisthrombendarterektomie.

BACKGROUND: The indications for carotid endarterectomy have been defined on the basis of several large prospective randomised trials. Today this operation is widely performed as primary and secondary stroke prevention in patients with high grade carotid artery stenosis. Permanent quality control of the surgical results is mandatory to ensure optimal stroke prevention and further reduce perioperative complications. METHODS: In this retrospective study we analyse the surgical results of 272 consecutive carotid endarterectomies performed in 260 patients with special emphasis on the prevention of intraoperative brain ischaemia. Patients were operated on in general anaesthesia and moderate hypothermia. Before clamping the arteries at the neck, a fast-acting barbiturate or propofol was administered intravenously to obtain burst suppression on the EEG. Transcranial Doppler sonography allowed continuous intraoperative monitoring of brain perfusion and detection of emboli. Intraoperative shunting was performed only when the collateral circulation was insufficient. RESULTS: The postoperative course was uneventful in 249 endarterectomies (91.5%). The internal carotid artery was sonographically recanalised at hospital discharge and at 6-week follow-up in all 249 cases. Ischaemic cerebral complications were observed in 7 patients (2.6%): minor reversible brain ischaemia in 4 (1.5%), and major brain ischaemia with infarction in 3 (1.1%). Three patients died in the perioperative period, representing a mortality rate of 1.1% in this series. The overall combined stroke and death rate was 3.7%. The combined major stroke and death rate was 2.2%. Various non cerebral complications occurred in 13 patients (4.8%). CONCLUSIONS: These results confirm that endarterectomy is a safe and efficient treatment for atherosclerotic carotid stenosis at the neck. Very low complication rates can be attained by non-invasive diagnostic methods combined with intraoperative monitoring of cerebral blood flow velocity. New upcoming endovascular therapies such as percutaneous angioplasty and stenting need to be compared with these current surgical results with regard not only to perioperative morbidity and mortality but also patency rate, restenosis, and intracerebral blood flow restoration.

Potential interactions between alternative therapies and warfarin.

Potential and documented interactions between alternative therapy agents and warfarin are discussed. An estimated one third of adults in the United States use alternative therapies, including herbs. A major safety concern is potential interactions of alternative medicine products with prescription medications. This issue is especially important with respect to drugs with narrow therapeutic indexes, such as warfarin. Herbal products that may potentially increase the risk of bleeding or potentiate the effects of warfarin therapy include angelica root, arnica flower, anise, asafoetida, bogbean, borage seed oil, bromelain, capsicum, celery, chamomile, clove, fenugreek, feverfew, garlic, ginger ginkgo, horse chestnut, licorice root, lovage root, meadowsweet, onion, parsley, passionflower herb, poplar, quassia, red clover, rue, sweet clover, turmeric, and willow bark. Products that have been associated with documented reports of potential interactions with warfarin include coenzyme Q10, danshen, devil's claw, dong quai, ginseng, green tea, papain, and vitamin E. Interpretation of the available information on herb-warfarin interactions is difficult because nearly all of it is based on in vitro data, animal studies, or individual case reports. More study is needed to confirm and assess the clinical significance of these potential interactions. There is evidence that a wide range of alternative therapy products have the potential to interact with warfarin. Pharmacists and other health care professionals should question all patients about use of alternative therapies and report documented interactions to FDA's MedWatch program.

Practical, reliable, comprehensive method for characterizing pharmacists' clinical activities.

A method for rating the value of pharmacists' clinical services was studied. An instrument was developed to measure the severity of medication errors and the value of pharmacists' clinical interventions. Pharmacists at a hospital pharmacy department used the instrument at the time they made an intervention. A single pharmacist reviewed and adjusted the scores assigned by the pharmacist who made the intervention. An expert panel consisting of two clinical pharmacists and two physicians also scored all the interventions using the same instrument. All rankings were compared using kappa (kappa) and weighted kappa statistics, and symmetry tests were applied to examine whether specific raters consistently rated higher or lower than other raters. Data were extracted from the pharmacy department's intervention database to rate 300 interventions. Agreement between the raters was substantial, both overall and for each dimension individually. However, the physicians rated severity of error and value of service lower than their pharmacist counterparts. The study indicated that severity of error and value of service are clearly related, but not linearly. Services can be identified as high value even when there are no prescribing errors. Pharmacists found the instrument usable and practical. A literature-based instrument for simultaneously assessing the severity of errors in medication orders and the value of pharmacists' interventions was constructed, tested in a hospital, and determined to be reliable.

Extracellular matrix degradation by metalloproteinases and central nervous system diseases.

Matrix metalloproteinases (MMPs) are a gene family of neutral proteases involved in normal and pathological processes in the central nervous system (CNS). Normally released into the extracellular space, MMPs break down the extracellular matrix (ECM) to allow cell growth and to facilitate remodeling. Proteolysis becomes pathological when the normal balance between the proteases and their inhibitors, tissue inhibitors to metalloproteinases (TIMPs), is lost. Cancer cells secrete neutral proteases to facilitate spread through the ECM. MMPs increase capillary permeability, and they have been implicated in demyelination. Neurological diseases, such as brain tumors, multiple sclerosis, Guillain-Barré, ischemia, Alzheimer's disease, and infections, lead to an increase in the matrix-degrading proteases. Two classes of neutral proteases have been extensively studied, namely the MMPs and the plasminogen activators (PAs), which act in concert to attack the ECM. After proteolytic injury occurs, the process of ECM remodeling begins, which can lead to fibrosis of blood vessels and gliosis. TIMPs are increased after the acute injury and may add to the fibrotic buildup of ECM components. Thus, an imbalance in proteolytic activity either during the acute injury or in recovery may aggravate the underlying disease process. Agents that affect the proteolytic process at any of the regulating sites are potentially useful in therapy.

Surgical treatment of lumbar spinal stenosis in the elderly.

148 elderly patients, aged 70 years or more, diagnosed as having lumbar spinal stenosis, were operated upon at our institution during 1983 to 1995. Totally 161 operative procedures were performed. We analysed retrospectively the results of the surgical treatment. The most frequently performed procedure was multisegmental laminectomy, in 32% interlaminar fenestration and laminotomy were done. In 9 cases fusion was indicated, two of them being secondary operations. The mean hospital stay was 11 days. The morbidity was 6%, and there was one fatality (0.6%). The outcome was determined according to the six-grade classification proposed by Pappas and Sonntag [25]. Overall, in 91% of cases satisfactory-to-excellent results could be achieved. We conclude, that in elderly patients with symptomatic lumbar spinal stenosis, with no evidence of instability, decompressive surgery without stabilisation can be done in the majority of patients with low morbidity and high expectation of clinical improvement.

Fetal fibronectin as a predictor of preterm birth in patients with symptoms: a multicenter trial.

OBJECTIVE: Our aim was to determine whether the presence of fetal fibronectin in vaginal secretions of patients with symptoms suggestive of preterm labor predicts preterm delivery. STUDY DESIGN: Patients who were examined at the hospital between 24 weeks' and 34 weeks 6 days' gestation with intact membranes, no prior tocolysis, symptoms suggestive of preterm labor, and cervical dilation < 3 cm were recruited at 10 sites. Swabs of the posterior fornix were assayed for the presence of fetal fibronectin by monoclonal antibody assay, with a positive result defined as > or = 50 ng/ml. Results were not available to the managing physicians. Tocolysis was used when clinically indicated after specimen collection. RESULTS: A total of 763 patients had fetal fibronectin results and pregnancy outcome data available for analysis. Fetal fibronectin was detected in specimens from 150 (20%) patients. Compared with patients who had negative results, patients who had positive results for fetal fibronectin were more likely to be delivered within 7 days (relative risk 25.9 [95% confidence interval 7.8 to 86]), within 14 days (relative risk 20.4 [95% confidence interval 8.0 to 53]), and before 37 completed weeks (relative risk 2.9 [95% confidence interval 2.2 to 3.7]). The negative predictive values for delivery within 7 days, within 14 days, and at < 37 weeks were 99.5%, 99.2%, and 84.5%, respectively. When we used multiple logistic regression analysis to control for potential confounding variables among singleton pregnancies, only the presence of fetal fibronectin (odds ratio 48.8, 95% confidence interval 7.4 to 320), prior preterm birth (odds ratio 8.3, 95% confidence interval 1.5 to 46.6), and tocolysis (odds ratio 4.1, 95% confidence interval 1.0 to 16.0) were associated with birth within 7 days; fetal fibronectin (odds ratio 3.6, 95% confidence interval 2.2 to 5.9), prior preterm birth (odds ratio 2.5, 95% confidence interval 1.4 to 4.4), cervical dilatation > 1 cm (odds ratio 2.9, 95% confidence interval 1.6 to 5.2), and tocolysis (odds ratio 4.5, 95% confidence interval 2.8 to 7.2) were all independently associated with delivery before 37 weeks. CONCLUSION: In a population of patients with symptoms, the presence of fetal fibronectin in vaginal secretions best defines a subgroup at increased risk for delivery within 7 days; the high negative predictive value of fetal fibronectin sampling supports less intervention for patients with this result.

Predictors of positivity for fetal fibronectin in patients with symptoms of preterm labor.

OBJECTIVE: Identifying patients at risk for preterm delivery continues to be difficult. We analyzed fetal fibronectin immunoassays in 763 subjects with threatened preterm delivery from 10 clinical sites. STUDY DESIGN: Symptomatic women between 24 weeks 0 days and 34 weeks 6 days with intact amniotic membranes and cervical dilatation <3 cm were included. Specimens were obtained from the posterior vaginal fornix and concentrations of fetal fibronectin were measured by enzyme-linked immunosorbent assay. A total of 150 (20%) patients had positive results for the fetal fibronectin immunoassay. The simultaneous effects of multiple variables on predicting positive fetal fibronectin immunoassay results were analyzed with use of logistic regression models. Variables included were patient age (mean 24.2 years), race (40% white), gravidity (29% primigravid), history of previous premature infants (15%), sexual activity within 24 hours of sample collection (66/763 or 9%), cervical examination within 24 hours of sample collection (107/763 or 14%), vaginal bleeding (118/759 or 16%), uterine contractions (192/750 or 26% with three or more in 1 hour), cervical dilatation (94/763 or 12% with dilatation between 1 and 3 cm), estimated gestational age at sampling (mean 30 weeks 2 days). RESULTS: Regardless of the variable selection process (e.g., forward, backward, or stepwise), the reduced model showed five significant variables in predicting positive fetal fibronectin: cervical dilatation (chi2 33.5, p = 0.0006), sexual activity within 24 hours of sample collection (chi2 22.9, p < 0.0001), presence of vaginal bleeding (chi2 17.0, p < 0.0001), cervical examination within 24 hours of sample collection (chi2 11.6, p < 0.0006), and uterine contractions (chi2 6.8, p = 0.01). Deletion of the true positive subset did not change these variables or the magnitude of risk. CONCLUSION: Cervical dilation or manipulation predicts positive fetal fibronectin assays and may serve to explain some of the false-positive results generated by the test.

[Spinal stenosis: current aspects of imaging diagnosis and therapy]. / Die spinale Stenose: Stand der bildgebenden Diagnostik und Therapie.

Lumbar spinal stenosis typically manifests itself through low back pain and neurogenic claudication during walking. Cervical spinal stenosis may manifest itself through a multitude of symptoms. Spinal stenosis is classified into congenital or primary and acquired or secondary forms. Conventional X-rays of the spine often reveal only unspecific findings. Computed tomography (CT) is the preferred method of judging the width and anatomy of the spinal canal. Myelography remains a good method of imaging the spinal cord in its entirety and in addition allows functional imaging of the width of the spinal canal with functional stress images. CT performed directly after myelography (myelo-CT) allows specific imaging of areas still unclear. Magnetic resonance imaging (MRI) allows multiplanar imaging of the spine and better soft tissue definition. Surgical therapy is discussed in relation to the clinical and neuroradiological findings.

Multivariable analysis of DNA ploidy, p53, and HER-2/neu as prognostic factors in endometrial cancer.

BACKGROUND: Several molecular-genetic alterations in endometrial cancers, including aneuploidy and aberrant expression of p53 and HER-2/neu, have been associated with poor prognosis. To determine the importance of molecular-genetic factors relative to more traditional surgical-pathologic prognostic factors, a multivariable analysis was performed. METHODS: Immunohistochemical staining for p53, HER-2/neu, estrogen receptor, progesterone receptor, and epidermal growth factor receptor was performed on frozen sections from 100 primary endometrial cancers. DNA ploidy was determined using computerized image analysis of Feulgen-stained touch preparations. In addition, information regarding surgical-pathologic features of the cancers was obtained. Univariable analysis was performed followed by multivariable analysis using Cox's proportional hazards model to identify variables predictive of poor prognosis. RESULTS: With univariable analysis, race, histologic type, stage, grade, myometrial invasion, estrogen receptor, progesterone receptor, ploidy, p53 and HER-2/neu were predictive of the presence of persistent or recurrent disease. In the multivariable analysis, only International Federation of Gynecology and Obstetrics stage (P = 0.005), grade (P = 0.005), myometrial invasion (P = 0.024), and ploidy (P = 0.028) were significant. CONCLUSIONS: Among molecular-genetic prognostic factors, DNA ploidy was the most strongly predictive of persistent or recurrent disease.

New criteria for diagnosis of infective endocarditis: utilization of specific echocardiographic findings. Duke Endocarditis Service.

PURPOSE: This study was designed to develop improved criteria for the diagnosis of infective endocarditis and to compare these criteria with currently accepted criteria in a large series of cases. PATIENTS AND METHODS: A total of 405 consecutive cases of suspected infective endocarditis in 353 patients evaluated in a tertiary care hospital from 1985 to 1992 were analyzed using new diagnostic criteria for endocarditis. We defined two "major criteria" (typical blood culture and positive echocardiogram) and six "minor criteria" (predisposition, fever, vascular phenomena, immunologic phenomena, suggestive echocardiogram, and suggestive microbiologic findings). We also defined three diagnostic categories: (1) "definite" by pathologic or clinical criteria, (2) "possible," and (3) "rejected." Each suspected case of endocarditis was classified using both old and new criteria. Sixty-nine pathologically proven cases were reclassified after exclusion of the surgical or autopsy findings, enabling comparison of clinical diagnostic criteria in proven cases. RESULTS: Fifty-five (80%) of the 69 pathologically confirmed cases were classified as clinically definite endocarditis. The older criteria classified only 35 (51%) of the 69 pathologically confirmed cases into the analogous probable category (p < 0.0001). Twelve (17%) pathologically confirmed cases were rejected by older clinical criteria, but none were rejected by the new criteria. Seventy-one (21%) of the remaining 336 cases that were not proven pathologically were probable by older criteria, whereas the new criteria almost doubled the number of definite cases, to 135 (40%, p < 0.01). Of the 150 cases rejected by older criteria, 11 were definite, 87 were possible, and 52 were rejected by the new criteria. CONCLUSION: Application of the proposed new criteria increases the number of definite diagnoses. This should be useful for more accurate diagnosis and classification of patients with suspected endocarditis and provide better entry criteria for epidemiologic studies and clinical trials.

Diagnosis of infective endocarditis.

The diagnosis of IE is often difficult to establish with certainty. Current diagnostic criteria have several weaknesses, the most important being failure to utilize the results of echocardiography. This seems inconsistent with modern practice. In reality, the results of modern echocardiography, including appropriate use of transesophageal echocardiography, are critically important for diagnosis of infective endocarditis. New criteria are in the process of development which should prove more sensitive and more specific for disease classification, epidemiologic studies, and clinical trials.

Disproportionation involving an organomercurial and a sulfhydryl-containing protein. Reaction between chloromercuryferrocene and bakers'-yeast cytochrome c.

Reaction between iso-1 cytochrome c from bakers' yeast and chloromercuryferrocene, FcHgCl, does not result in simple replacement of the sulfhydryl hydrogen atom in Cys 102 with the ferrocenylmercury group, FcHg. Instead, this reaction yields the protein monomer modified at Cys 102 with an HgCl+ group and the protein dimer in which the thiolate groups of Cys 102 are bridged by a mercury(II) atom. These proteins and other organometallic products are identified by chromatographic, spectroscopic, and electrochemical methods. Organomercurials of the type RHgX and biological thiols can undergo not only substitution reactions, but disproportionation reactions as well.