Pericardial fluid absorption into lymphatic vessels in sheep

We estimated the volumetric lymphatic clearance rate of pericardial fluid in sheep. In the first group of studies, 125I-human serum albumin (HSA) was injected into the pericardial cavity and after 4 h, various lymph nodes and tissues were excised and counted for radioactivity. Several lymphatic drainage pathways existed defined by elevated 125I-HSA in the middle and caudal mediastinal, intercostal, and the cardiac nodes located near the root of the aorta. In a second group of experiments, the plasma recovery of intrapericardially administered tracer was compared in sheep with intact lymphatics and in animals in which thoracic duct lymph was diverted and other relevant lymphatics ligated. The 4-h plasma recoveries were reduced significantly from an average of 12.2 +/- 3. 4% injected dose in the lymph-intact group to 3.0 +/- 1.1% injected dose in the diverted/ligated group (an inhibition of approximately 75%). In order to estimate the volumetric clearance of pericardial fluid through lymphatics in conscious sheep, 125I-HSA was administered into the pericardial cavity to serve as the lymph flow marker. 131I-HSA was injected intravenously to permit calculation of plasma tracer loss and tracer recirculation into lymphatics. From mass balance equations, total pericardial clearance into lymphatics averaged 1.50 +/- 0.43 ml/h or approximately 1.13 ml/h if one was to assume that the average 25% recovered plasma tracer in lymph diverted/ligated animals was due to nonlymphatic transport. In conclusion, mediastinal lymphatic pathways remove a volume equivalent to the pericardial volume (8.1 +/- 1.1 ml) every 5.4 to 7. 2 h.

Impact on patients and partners of inpatient and extended cardiac counseling and rehabilitation: a controlled trial

OBJECTIVES

This study evaluated the effectiveness of cardiac counseling and rehabilitation programs led by a nurse counselor, compared with normal care on outcomes for myocardial infarction (MI) patients and their partners.

METHODS

A randomized controlled trial with follow-up to 1 year was conducted with 100 patients recruited within 72 hours of a first MI and their partners: a Control group received normal care; an Inpatient group received cardiac rehabilitation from a nurse counselor while in hospital; and an Extended group received the same cardiac rehabilitation as the Inpatient group, but with additional sessions continuing up to 6 weeks after discharge from hospital. The scales for main outcome measures were 1) knowledge of heart disease and treatment (correct, misconceptions, and uncertainty); 2) mood (Hospital Anxiety and Depression Scale); 3) satisfaction; 4) disability (Functional Limitations Profile).

RESULTS

Inpatient cardiac counseling and rehabilitation resulted in more knowledge, less anxiety, less depression, and greater satisfaction with care in both patients and partners and in less disability in patients, with effects enduring to 1 year. There was some evidence of additional benefit from the Extended program. Both nurse counselors achieved benefits on all outcome variables.

CONCLUSIONS

This Inpatient cardiac counseling and rehabilitation program resulted in significant and enduring benefits of clinical value. It is likely that it would be acceptable to most post-MI patients, many of whom are not offered or are unable to accept outpatient cardiac rehabilitation.

Binding of the glucose-dependent Mig1p repressor to the GAL1 and GAL4 promoters in vivo: regulationby glucose and chromatin structure

Binding of the MIG1 repressor to the glucose-repressible GAL1 and GAL4 promoters was analyzed in vivo by cyclobutane dimer footprinting in two yeast strains that show different glucose repression responses. Mig1p binding to the two promoters in both strains was glucose-induced. In cells subject to rapid and stringent glucose repression (S288c), long-term Mig1p binding in glucose-grown cells was inhibited by the formation of a competing chromatin structure. Under conditions where glucose repression was only partially effective (gal80 - or low glucose), the chromatin structure did not form and long-term Mig1p binding was observed The same long-term binding of Mig1p was seen in cells of a different strain (W303A) that shows only partial glucose repression of the GAL1 promoter. We conclude from these experiments that Mig1p binding to glucose-repressed promoters is glucose-dependent but transient. We suggest that Mig1p functions at an early step in repression, but is not required to maintain the repressed state.

The influence of developmental haemostasis on the laboratory diagnosis and management of haemostatic disorders during infancy and childhood

The physiology of the hemostatic system in children is different from that in adults. Reference ranges for components of the hemostatic system are age dependent. During early childhood, physiologic values may overlap with values observed in congenital deficiencies of acquired pathological conditions. Physiologically decreased plasma concentrations of hemostatic components also influence the response to antithrombotic therapy. The relevance of developmental hemostasis for the laboratory diagnosis and management of hemorrhagic and thrombotic disorders during childhood is discussed.

Contribution of extracranial lymphatics and arachnoid villi to the clearance of a CSF tracer in the rat

The objective of this study was to determine the relative roles of arachnoid villi and cervical lymphatics in the clearance of a cerebrospinal fluid (CSF) tracer in rats. 125I-labeled human serum albumin (125I-HSA; 100 micrograms) was injected into one lateral ventricle, and an Evans blue dye-rat protein complex was injected intravenously. Arterial blood was sampled for 3 h. Immediately after this, multiple cervical vessels were ligated in the same animals, and plasma recoveries were monitored for a further 3 h after the intracerebroventricular injection of 100 micrograms 131I-HSA. Tracer recovery in plasma at 3 h averaged (%injected dose) 0.697 +/- 0.042 before lymphatic ligation and dropped significantly to 0.357 +/- 0. 060 after ligation. Estimates of the rate constant associated with the transport of the CSF tracer to plasma were also significantly lower after obstruction of cervical lymphatics (from 0.584 +/- 0. 072/h to 0.217 +/- 0.056/h). No significant changes were observed in sham-operated animals. Assuming that the movement of the CSF tracer to plasma in lymph-ligated animals was a result of arachnoid villi clearance, we conclude that arachnoid villi and extracranial lymphatic pathways contributed equally to the clearance of the CSF tracer from the cranial vault.

Vasoflux, a new anticoagulant with a novel mechanism of action

BACKGROUND

Heparin and direct thrombin inhibitors, such as hirudin, have limitations in the treatment of acute coronary syndromes. Heparin does not inactivate fibrin-bound thrombin, whereas hirudin fails to block thrombin generation. In contrast, Vasoflux is a novel anticoagulant that inactivates fibrin-bound thrombin and attenuates factor Xa generation.

METHODS AND RESULTS

Vasoflux is prepared by depolymerization of heparin, restricting molecular size to between 3000 and 8000 Da, and reducing antithrombin affinity by periodate oxidation. Vasoflux catalyzes fibrin-bound thrombin inactivation by heparin cofactor II (HCII) and inhibits factor IXa activation of factor X independently of antithrombin and HCII. Compared with other anticoagulants in a thrombogenic extracorporeal circuit, Vasoflux maintains filter patency at concentrations that produce an activated clotting time (ACT) of 220 seconds. In contrast, to maintain filter patency, heparin, low-molecular-weight heparin (LMWH), and hirudin require concentrations that produced an ACT of 720, 415, and >1500 seconds, respectively, whereas dermatan sulfate was ineffective at concentrations that produced an ACT of 360 seconds.

CONCLUSIONS

Vasoflux is more effective than heparin and LMWH because it inactivates fibrin-bound thrombin and is superior to hirudin and dermatan sulfate because it also blocks factor Xa generation.

Feasting, fasting and fermenting. Glucose sensing in yeast and other cells

Glucose is the primary fuel for most cells. Because the amount of available glucose can fluctuate wildly, organisms must sense the amount available to them and respond appropriately. Altering gene expression is one of the major effects glucose has on cells. Two different glucose sensing and signal transduction pathways in the yeast S. cerevisiae--one for repression, and one for induction of gene expression--have recently come into focus. What we have learned about these glucose sensing and signaling mechanisms might shed light on how other cells sense and respond to glucose.

Influence of three types of automated coagulometers on the international sensitivity index (ISI) of rabbit, human, and recombinant human tissue factor preparations--a multicenter study

Five tissue factor reagents and three types of automated instruments for prothrombin time (PT) determination were studied in an international multicenter collaborative exercise. The purpose of this work was to determine the international sensitivity index (ISI) for each combination of reagent and instrument against the international reference preparation RBT/90. Each type of instrument was used by 3 or 4 centers to assess the interlaboratory variation of the ISI. The interlaboratory variation of the ISI for each combination of reagent and instrument ranged between 0.4% and 7.8% coefficient of variation. For three reagents, the mean ISI values for ACL (nephelometric) and STA (mechanical) were practically identical, but the mean ISI values for MLA (photo-optical) were at least 10% higher. For two other reagents prepared from rabbit tissue, the mean ISI values increased in the order ACL, STA, MLA. The widest range of mean ISI values was noted with one rabbit tissue factor reagent: 1.68 for ACL and 2.00 for MLA. Exclusion of patient specimens with INR <1.5 and INR >4.5 determined by the international reference preparation resulted in a slight decrease of the mean ISI. The interlaboratory variation of the International Normalized Ratio (INR) was assessed from the results obtained with common lyophilized and deep-frozen plasmas. The use of instrument-specific ISI values resulted in reduced interlaboratory variation of the INR. It is recommended that thromboplastin manufacturers provide instrument-specific ISI values.

Characterization of three related glucose repressors and genes they regulate in Saccharomyces cerevisiae

Mig1 and Mig2 are proteins with similar zinc fingers that are required for glucose repression of SUC2 expression. Mig1, but not Mig2, is required for repression of some other glucose-repressed genes, including the GAL genes. A second homolog of Mig1, Yer028, appears to be a glucose-dependent transcriptional repressor that binds to the Mig1-binding sites in the SUC2 promoter, but is not involved in glucose repression of SUC2 expression. Despite their functional redundancy, we found several significant differences between Mig1 and Mig2: (1) in the absence of glucose, Mig1, but not Mig2, is inactivated by the Snf1 protein kinase; (2) nuclear localization of Mig1, but not Mig2, is regulated by glucose; (3) expression of MIG1, but not MIG2, is repressed by glucose; and (4) Mig1 and Mig2 bind to similar sites but with different relative affinities. By two approaches, we have identified many genes regulated by Mig1 and Mig2, and confirmed a role for Mig1 and Mig2 in repression of several of them. We found no genes repressed by Yer028. Also, we identified no genes repressed by only Mig1 or Mig2. Thus, Mig1 and Mig2 are redundant glucose repressors of many genes.

Cerebral spinal fluid lymphocytes are part of the normal recirculating lymphocyte pool

We have investigated the migration of lymphocytes from blood into the central nervous system (CNS) under normal physiological conditions. Using sheep as our model, we simultaneously sampled blood, lymph and cerebral spinal fluid (CSF). Normal, nonactivated, recirculating lymphocytes can migrate into the CSF in similar concentrations as found in subcutaneous lymph and there is no difference in the temporal appearance between them. Lymphocytes infused into the CNS could be found in cervical lymph nodes. These data suggest that lymphocytes found in the CNS are part of the recirculating lymphocyte pool and do not require activation to enter the CSF.

A cross-Canada survey of prothrombin time testing: Does the establishment of local ISI values improve the accuracy of international normalized ratio reporting? Thrombosis Interest Group of Canada

The international normalized ratio (INR) was established as a means of standardizing the prothrombin time regardless of the thromboplastin used in the individual laboratories. The INR is the prothrombin time ratio of the sample raised to the power of the International Sensitivity Index (ISI). Traditionally, the ISI is determined by using a manual clotting technique by comparing the test thromboplastin with a World Health Organization international reference thromboplastin with results from 60 patient samples standardized on warfarin, and 20 samples from normal volunteers. Most laboratories no longer perform prothrombin time testing by a manual technique but instead automate the procedure by using a variety of coagulation instruments. Thromboplastin ISI values have the potential to be modified considerably by instrumentation, and as a consequence, they, may result in INRs that are unreliable when compared to those obtained by the traditional manual method. It has been proposed that the use of calibrant plasmas tested with the laboratory's thromboplastin and instrument may overcome this problem and a local ISI value could be established. Our study objective was to determine whether a local ISI calibration with the plasma calibrants could reduce the variation of the INR over a wide range of thromboplastin/ instrument combinations. A total of 58 laboratories from across Canada, including community hospitals, private laboratories, and large tertiary care units, participated. The findings indicate that the use of calibrant plasmas to calculate the local ISI does improve the accuracy of INR reporting in the majority of thromboplastin/instrument combinations.

Does refrigeration of urine alter culture results in hospitalized patients with neurogenic bladders?

A prospective, blinded study of 40 hospitalized spinal cord injured (SCI) patients was conducted to evaluate the effects of refrigeration on urinalysis and culture results. Urine samples were divided, with one aliquot examined within 4 hours and the other after 24 hours of refrigeration. Comparisons using Wilcoxon Signed Rank analysis showed no significant difference between fresh and refrigerated samples in white blood cell (WBC) count (z = -0.353, p = 0.724), number of bacteria (z = -0.772, p = 0.440), leukocytes (z = -0.277, p = 0.782), or colony counts of E. fecalis, E. coli, Citrobacter, Pseudomonas, Streptococcus, Yeast, or Acinetobacter (z = -1.00, p = 0.317; z = 0.00, p = 1.0; z = 0.00, p = 1.0; z = 0.00, p = 1.0; z = -1.00, p = 0.317; z = 0.00, p = 1.0; z = 0.00, p = 1.0, respectively). A statistically significant difference between fresh and refrigerated samples was found with "mixed" organisms (z = -2.565, p = 0.010) and a difference approaching significance was found with Staph aureus (z = -1.841, p = 0.066), both with colony counts of less than 50 k. No changes in cultures or colony counts occurred following refrigeration that would have resulted in altered treatment regimens. This study indicates that refrigeration of urine samples for up to 24 hours in the hospital setting rarely causes changes in identified organism type and causes no clinically significant changes in urinalysis or urine culture results in SCI patients.

Hirudin causes more bleeding than heparin in a rabbit ear bleeding model

This study was undertaken to determine the appropriateness of the current practice of using the activated partial thromboplastin time (APTT) to select hirudin doses. A rabbit bleeding ear model was used to compare the effects of various doses of heparin and hirudin on the relationship between the APTT and bleeding. In addition, the effects of these agents on the thrombin clotting time (TCT) and factor Xa clotting time also were examined. Both heparin and hirudin produced a concentration-dependent increase in bleeding. When bleeding was plotted as a function of APTT ratio, even a small increase in APTT ratio within the therapeutic range of 1.5 to 2.5 resulted in a marked increase in bleeding with hirudin but not with heparin. The TCT was more responsive than the APTT or factor Xa clotting time to increases in hirudin-induced bleeding. In this model, hirudin produces more bleeding than heparin when the agents are used in doses that increase the APTT ratio to the same extent. These studies highlight the pitfalls of extrapolating from experience with heparin when choosing a test to monitor new antithrombotics. Our findings also suggest that the TCT may be more responsive than the APTT for monitoring hirudin therapy.

Raised intracranial pressure increases CSF drainage through arachnoid villi and extracranial lymphatics

We demonstrated previously that about one-half of cerebrospinal fluid (CSF) removed from the cranial vault was cleared by extracranial lymphatic vessels. In this report we test the hypothesis that lymphatic drainage of CSF increases as intracranial pressure (ICP) is elevated in anesthetized sheep. Catheters were inserted into both lateral ventricles, cisterna magna, cervical lymphatics, and jugular vein. A ventriculocisternal perfusion system was employed to regulate CSF pressures and to deliver a protein tracer (125I-labeled human serum albumin) into the CSF compartment. 131I-labeled human serum albumin was injected intravenously to permit calculation of plasma tracer loss and tracer recirculation into lymphatics. ICP was controlled by adjusting the height of the inflow reservoir and the cisterna magna outflow catheter appropriately. The experimental design consisted of a 3-h period of lower pressure followed by a 3-h period of higher pressure in the same animal (10-20 or 20-30 cmH2O). We determined that incremental changes in ICP were associated with higher CSF transport through lymphatic and arachnoid villi routes in all eight animals tested (P = 0.004).

Health benefits of joint replacement surgery for patients with osteoarthritis: prospective evaluation using independent assessments in Scotland

STUDY OBJECTIVES

To determine extent of change in psychological, functional, and social health after knee and hip joint replacement surgery using independent assessments.

DESIGN

Patients were recruited before surgery and interviewed preoperatively, three months after surgery, and nine months after surgery. Interviews were conducted in the patients' own homes.

SETTING

Two orthopaedic surgery units in Scotland.

PARTICIPANTS

A consecutive sample of 107 patients with osteoarthritis having primary replacement of the knee or hip.

MAIN OUTCOME MEASURES

Assessments of depression, anxiety, pain, functional activity, informal care, and formal service utilisation were made at three time points.

MAIN RESULTS

Anxiety and pain were significantly reduced and functional activity levels significantly increased after surgery. While gains in anxiety and pain reduction occurred between the preoperative and three month assessments, gains in activity were made between the three month and nine month assessments. Although pain was reduced and activity increased, levels of depression were unchanged after surgery. Patients reported need for assistance with fewer activities after surgery, but increases in the use of formal services and increases in the number of hours per week of informal support received were observed at both three month and nine month follow up.

CONCLUSIONS

The main benefit of joint replacement surgery is pain relief. Gains in functional activity, particularly mobility and leisure activities are made by many patients. Paradoxically, surgery for osteoarthritis seems to act as a "gateway" to increases in formal and informal community support, which are maintained into the longer term.

Assessment of individual quality of life in survivors of intensive care

Quality of life is a dynamic, multi-dimensional concept, the essence of which is its individuality. In this study quality of life six to 12 months after intensive care was not significantly lower than quality of life prior to intensive care, assessed retrospectively. Family, leisure activities and people were seen as more important than health as a main determinant of quality of life after intensive care. Quality of life assessment after intensive care should combine generic measures of health status and individual measures.

Treatment of acute deep vein thrombosis in spinal cord injured patients with enoxaparin: a cost analysis

Enoxaparin, a low molecular weight heparin, has been demonstrated to be effective in the prophylaxis and treatment of deep vein thrombosis (DVT) in the general population. This study presents an analysis of the costs of subcutaneous (SQ) enoxaparin compared with intravenous (IV) heparin. Data were gathered on six spinal cord injured (SCI) patients in an acute freestanding rehabilitation center who were initially treated with SQ enoxaparin (n=3) or IV heparin (n=3) for a proximal DVT. No patients in either group developed further clinical complications. Comparison of the total costs of each treatment was performed, including the direct cost of the drug, as well as some of the costs of administration. Although the cost of enoxaparin per unit dose is higher, the total costs of enoxaparin are slightly lower, because its labor and administration costs are less. Subcutaneous enoxaparin is a safe, cost-effective, and less labor-intensive treatment, and can be of substantial benefit in the treatment of DVT in SCI patients in the rehabilitation setting.

Cognitive representations of illness and functional and affective adjustment following surgery for osteoarthritis

A prospective investigation is described which sought to test the role of illness cognitions in determining patient responses to a surgical intervention for osteoarthritis. Illness cognitions were assessed amongst a consecutive sample of patients with osteoarthritis of the knee or hip prior to undergoing joint replacement surgery. Functional activity and depression were assessed pre-operatively, and at 3 and 9 months post surgery. At pre-operative assessment, functional activity and depression were univariately associated with the perceived consequences of osteoarthritis. Path analyses using longitudinal data demonstrated that illness cognitions had predictive value in explaining outcomes. Depression at 3 months was associated with higher pre-operative perceived control beliefs suggesting that patients who have high control pre-operatively may be at risk for temporary depressed mood in the immediate aftermath of surgery. This effect was not maintained at 9 months. Depression at 9 months was lower amongst patients who were more active at 3 months, who did not attribute their condition to wear and tear and who had higher expectations of surgery. Functional activity at 9 months was higher amongst those who did not attribute their condition to growing older and who perceived more control over symptoms. Socio-demographic variables were not associated with change in functional activity or depression over the course of surgery. The results provide support for an illness cognition approach in explaining functional activity and depression outcomes following surgery.

Effectiveness and patient satisfaction with nurse-directed treatment of Barrett's esophagus

OBJECTIVE

Using clinical practice guidelines, a registered nurse adjusted antireflux medications, evaluated esophageal biopsy reports, determined the interval between surveillance endoscopies, and provided education for patients with Barrett's esophagus. No previous reports have assessed the effectiveness or patient satisfaction associated with registered nurse-provided primary care. Because estimates of the incidence of dysplasia and adenocarcinoma vary widely, we also prospectively followed a cohort of patients with Barrett's esophagus.

METHODS

Charts were reviewed to determine the frequency of variation from guidelines, the annual incidence of dysplasia and adenocarcinoma, and frequency of reflux symptoms. Patients were mailed a questionnaire to assess satisfaction with their medical care and with the nurse.

RESULTS

Variation by the nurse from the guidelines on surveillance endoscopy (1.9%) and the treatment of reflux (1.3%) was rare. Most patients were very satisfied (score of 6 on 0-6-point Likert scale) with overall medical care (88%), and patient education (76%), and most patients did not think that increased physician involvement would improve their care (93%). Ninety-seven percent of patients had control of reflux symptoms. Two patients with long segment Barrett's esophagus (n = 67) developed high grade dysplasia over 323 patient-yr of follow-up (1 of 162 patient-yr for an annual incidence of 0.6%). No patients with short segment Barrett's esophagus (n = 56) developed high grade dysplasia or adenocarcinoma over 172 patient-years of follow-up.

CONCLUSION

The registered nurse in our clinical setting effectively administered clinical practice guidelines for the management of Barrett's esophagus without clinically significant morbidity or patient dissatisfaction. Before these results can be generalized to other settings, further studies will need to be performed.

Effect of warfarin on activated partial thromboplastin time in patients receiving heparin

BACKGROUND

The activated partial thromboplastin time (APTT) is used to adjust heparin sodium dosage. However, warfarin sodium is often administered concomitantly with heparin and may also affect the APTT and, therefore, heparin dose. We performed a prospective cohort study to quantify the effect of warfarin on the APTT in patients who are being treated with heparin.

METHODS

Serial assays of APTT, international normalized ratio, heparin levels, and functional levels of prothrombin (factor II) and factors VII and X were performed in 24 patients with acute venous thromboembolism who were treated with concomitant continuous intravenous heparin and warfarin. The effects of warfarin, as expressed by international normalized ratio and coagulation factor levels, on APTT were determined.

RESULTS

Warfarin markedly affected APTT; for each increase of 1.0 in the international normalized ratio, the APTT increased 16 seconds (95% confidence interval, 10-22 seconds). The effects of warfarin and heparin on APTT were additive. Consequently, warfarin markedly altered the relationship between APTT and heparin levels; of the 29 blood samples with supratherapeutic APTT, 13 had a therapeutic heparin level and 10 had a subtherapeutic heparin level.

CONCLUSIONS

In patients receiving concomitant heparin and warfarin therapy, APTT reflects the combined effects of both drugs. Because of the marked effect of warfarin on the APTT, decreasing heparin dose in response to a high APTT frequently results in subtherapeutic heparin levels.

Glucose sensing and signaling by two glucose receptors in the yeast Saccharomyces cerevisiae

How eukaryotic cells sense availability of glucose, their preferred carbon and energy source, is an important, unsolved problem. Bakers' yeast (Saccharomyces cerevisiae) uses two glucose transporter homologs, Snf3 and Rgt2, as glucose sensors that generate a signal for induction of expression of genes encoding hexose transporters (HXT genes). We present evidence that these proteins generate an intracellular glucose signal without transporting glucose. The Snf3 and Rgt2 glucose sensors contain unusually long C-terminal tails that are predicted to be in the cytoplasm. These tails appear to be the signaling domains of Snf3 and Rgt2 because they are necessary for glucose signaling by Snf3 and Rgt2, and transplantation of the C-terminal tail of Snf3 onto the Hxt1 and Hxt2 glucose transporters converts them into glucose sensors that can generate a signal for glucose-induced HXT gene expression. These results support the idea that yeast senses glucose using two modified glucose transporters that serve as glucose receptors.

Improving emotional outcomes following acute stroke: a preliminary evaluation of work-book based intervention

Sixteen acute stroke patients (6 males and 10 females) who received a self-help workbook addressing both medical and psychological issues on discharge from hospital showed Significantly lower anxiety and depression levels and a non-significant trend toward greater satisfaction with advice/information than 53 patient controls. (28 male, 25 female) recruited to an earlier study who did not receive the workbook. All patients had been admitted to hospital with a first stroke, were aged less than 80 years, and had a residual disability at discharge. There were no significant group differences in age, sex distribution or neurological impairment measured within 48 hours of admission to hospital, thus our findings suggest that a workbook-based intervention can improve short-term emotional outcomes. A large-scale randomised controlled trial is needed.

Homozygous protein C deficiency: description of a new mutation and successful treatment with low molecular weight heparin

We present a kindred with a new mutation of the protein C gene, in which the proband had an unusual clinical presentation. The relationship between warfarin induced skin necrosis and level of anticoagulation was investigated. The pharmacokinetics of protein C concentrate was assessed to determine frequency of replacement therapy. The clinical and biochemical efficacy of therapy with low molecular weight heparin (LMWH) was assessed. The effect of long-term LMWH on bone density in the growing child was monitored using whole body densitometry. Warfarin therapy required an INR of greater than 3.5 to avoid skin necrosis. If protein C replacement was to be used, doses of 100 U/kg/day would have been required to maintain protein C levels consistently at or above 0.20 U/ml. While receiving prophylactic therapy with LMWH for almost 3 years, there were no episodes of recurrent thrombosis, no skin necrosis and no bleeding. Biochemical markers of in vivo thrombin generation were suppressed and within the normal range. Bone density continued to increase at the normal rate throughout the treatment period. LMWH is an effective form of long-term therapy for homozygous protein C deficient patients with measurable protein C levels.