Von Willebrand's factor mediates the adherence of human tumoral cells to human endothelial cells and ticlopidine interferes with this effect

The aim of this study was to explore whether von Willebrand's factor (vWF) plays a role in the adhesion of human colon tumor cells to human endothelial cells in our coculture system. Cell colony density was evaluated basally (endothelial plus colon tumor cells) and following the addition of: purified vWF, vWF plus vWF-blocking antibodies, antibodies against various integrins and adhesion molecules (alpha2 b integrin, beta1 integrin, beta3 integrin, intercellular adhesion molecule-I, intercellular adhesion molecule-II, vitronectin receptor CD61 CD51, laminin alpha6/beta4 receptor), and various drugs inhibiting the hemostatic system (ticlopidine, heparin, acetyl salicylic acid [ASA], defibrotide, indobuphen, dipyridamole, sulfinpyrazone). Furthermore, vWF concentration was measured in the supernatant fluid of the coculture system basally and following the addition of the above-listed drugs. Cell colony density (as measured by light absorption) increased by 33% following the addition of vWF and returned to a value similar to the basal level with antibodies against vWF, while it did not change significantly following the addition of antibodies against the other integrins or adhesion molecules tested. The same parameter was reduced by 35% following the addition of ticlopidine, while it showed a smaller or no change with the other drugs tested. Similarly, vWF concentration in the cell coculture supernatant showed the greatest reduction (from 0.22 to 0.11 mg/mL) following the addition of ticlopidine. These data suggest that vWF mediates the adherence of human tumor cells to human endothelial cells and that ticlopidine interferes with this effect.

Nuclear medicine imaging procedures in differentiated thyroid carcinoma patients with negative iodine scan

Radioiodine treatment following surgery is an effective therapy in differentiated thyroid carcinoma (DTC) patients. However, in DTC patients with metastases characterized by very low or absent iodine uptake, total thyroidectomy and radical loco-regional lymphoadenectomy is the only effective therapeutic approach. In the present article, we have discussed the most recently available nuclear medicine techniques utilized for the detection of DTC metastases that have lost the capacity to trap radioiodine. A review of the data published in the literature has been presented, and a comparative analysis made of the results obtained by other imaging modalities such as high resolution neck ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI). In our experience, the most sensitive and accurate imaging procedure is represented by the combination of neck US and whole body 99mTc-methoxy-isobutylisonitrile (99mTc-MIBI) scintigraphy; this combination might be proposed as a first-line diagnostic approach in DTC patients with increased serum thyroglobulin (Tg) levels and negative high dose 131I scans.

Postoperative follow-up of breast cancer patients: overview and progress in the use of tumor markers

The role of serial measurement of serum tumor-associated antigens (TAA) in the postoperative follow-up of breast cancer patients is not considered by most authors. The authors of this article review the literature and original data showing benefits from the use of TAA in the postoperative follow-up of breast cancer patients. An increase in the lead time from the first pathological finding to the definite evidence of distant metastases has been observed in follow-up studies which have used TAA compared to those which did not use them. The sensitivity and specificity of TAA in the diagnosis of distant metastases have been markedly improved by selecting an appropriate combination of TAA and by identifying specific conditions associated with breast cancer responsible for false-positive results as well as by adopting a 'dynamic' evaluation of multiple successive determinations of TAA. TAA accurately predict patients with bone metastases and can be used to guide imaging techniques. The anticipation of distant metastasis by TAA can be used to initiate a relatively early treatment which has been shown to prolong overall survival in a previous study. It is hoped that these data will stimulate further trials including TAA in the follow-up of breast cancer patients.

The role of large-needle aspiration biopsy in the preoperative selection of palpable thyroid nodules: a summary of principal data

This report summarizes clinical and pathologic data showing the role of preoperative large-needle aspiration biopsy (LNAB) histology for a better evaluation of the palpable thyroid nodules that were non-diagnostic or microfollicular at fine-needle aspiration (FNA) cytology. LNAB performed on 261 nodules with non-diagnostic cytology showed findings which were adequate for diagnosis in 130 (49.8%) and inadequate in 131 (50.2%) cases. Two hundred sixty nodules that were diagnosed as microfollicular at FNA were also examined by LNAB; inadequate specimens were obtained in 17% of cases; pure microfollicular structure was confirmed by aspiration needle biopsy in 35% of the nodules and LNAB showed the remaining 48% to contain a macrofollicular component suggesting a benign hyperplastic lesion. Seventeen nodules that were found to be microfollicular at FNA and micromacrofollicular at LNAB were excised and the postoperative result was benign in all cases. Twenty-five nodules diagnosed as microfollicular on both FNA and LNAB were excised and the postoperative diagnoses were benign (20 nodules) or malignant (five nodules). These data indicate that LNAB histology can be used for the preoperative selection of the palpable thyroid nodules that were non-diagnostic or microfollicular at FNA cytology.

Large-needle aspiration biopsy for the preoperative selection of palpable thyroid nodules diagnosed by fine-needle aspiration as a microfollicular nodule or suspected cancer

The palpable thyroid nodules with a fine-needle aspiration (FNA) diagnosis of microfollicular nodule or suspected cancer usually are excised; however, most of them are proved benign by postoperative histologic examination. We reviewed the clinical and pathologic data for patients with thyroid nodules with an FNA diagnosis of microfollicular nodule or suspected cancer; nodules also were examined by large-needle aspiration biopsy (LNAB) to assess whether the distinction achieved by LNAB into pure microfollicular or mixed microfollicular-macrofollicular nodules could be used preoperatively to better predict malignancy. One hundred fourteen nodules of this type were excised. The prevalence of cancer was 22% (14/63) among the microfollicular and 4% (2/51) among the microfollicular-macrofollicular nodules at LNAB. These data indicate that histologic examination of the LNAB specimen can be used for preoperative selection of thyroid nodules diagnosed by FNA as a microfollicular nodule or suspected cancer.

The expanding use of forensics in environmental science

Advances in the scientific investigation of environmental crimes are defining the emerging discipline of environmental forensics.

Antithrombotic and prothrombotic activities of the vascular endothelium

Vascular endothelium plays a key role in the control of haemostasis and thrombosis. The main reactions involved in the regulation of platelet reactivity, blood coagulation and fibrinolysis take place at the luminal surface of endothelial cells. Following exposure to certain pathological stimuli, remarkable functional changes of the endothelial cells occur, including downregulation of antithrombotic mechanisms and upregulation of prothrombotic activities. Based on the recent knowledge of vascular endothelial function, a better understanding of the pathogenesis of atherothrombosis is expected.

Comparison of CMF (cyclophosphamide, methotrexate, and 5-fluorouracil) with a rotational crossing and a sequential intensification regimen in advanced breast cancer: a prospective randomized study

The Italian Oncology Group for Clinical Research tested two experimental chemotherapy strategies in an attempt to improve the results achievable with conventional chemotherapy in metastatic breast cancer. One hundred sixty-two patients were randomly allocated as follows: (a) to the conventional cyclophosphamide, methotrexate, 5-fluorouracil chemotherapy regimen (CMF); (b) to a rotational crossing program (ROT-CROSS); or (c) to a sequential intensification program (SEQ-INT). The same single agents (C, M, F, cisplatin, etoposide, and doxorubicin) were administered in both experimental arms, but following a different policy. The SEQ-INT program induced a significantly higher complete response (32% vs. 6%, p = 0.0006) and objective response rate (72% vs. 42%, p = 0.0047) than CMF did. There were no differences in survival between CMF and either experimental arm. A number of side effects were significantly more with both experimental chemotherapies than with CMF, but the treatments were generally tolerable. Although some caution is required when interpreting a significant advantage found between an entire chemotherapeutic strategy and a single conventional combination, this study documents the potential therapeutic advantage of administering different sequential chemotherapies, and changing each at the time of maximum result without waiting for a progression. The impressive cytoreductive effects achievable with this policy (SEQ-INT) in metastatic disease merit further investigation in the adjuvant setting.

Vestibular disorders in primary thrombocytosis

OBJECTIVE

Balance disturbances are some of the most common symptoms among the clinical manifestations of chronic myeloproliferative disorders (MPDs) with a high platelet count, such as essential thrombocythaemia (ET) and polycythaemia vera (PV). In this study, we evaluated the vestibulo-oculomotor and vestibulospinal reflexes in a group of patients suffering from these diseases.

DESIGN

Evaluation of balance disturbances.

SETTING

Department of Neurosciences, ENT Unit, University of Pisa, Italy.

METHOD

In this study, we evaluated 43 patients suffering from ET and PV who underwent otoneurologic examination, based on a study of the vestibulo-oculomotor and vestibulospinal reflexes.

RESULTS

There was exclusive central vestibular involvement in 26 cases (60.4%), peripheral and central signs were associated in 8 cases (18.6%), and the involvement was purely peripheral in 1 patient. In six patients (14%), the otoneurologic examination revealed no alterations.

CONCLUSIONS

The high percentage of balance disorders in cases of ET and PV probably depends upon disorders of the microcirculation due to platelet dysfunction. We also postulate a full explanation of the involvement of the central vestibular system on the basis of a greater availability of central activated serotonin acting as neuromediator.

Protocols for the preoperative selection of palpable thyroid nodules: review and progress

Modern protocols for the management of patients with palpable thyroid nodules agree that fine-needle aspiration is the first examination to be performed. However, they differ very much in the role attributed to scintigraphy and ultrasound examinations. In some protocols, these two techniques are not considered, whereas in others they are recommended at the end of the diagnostic workup to select for surgery those nodules with nondiagnostic or suspect fine-needle aspiration biopsy results. We report original data and literature showing that such use of scintigraphy and ultrasonography is not cost effective. Furthermore, we report original data showing that large-needle aspiration biopsy can be used to select for surgery those nodules with nondiagnostic or suspect results after fine-needle aspiration. Consequently, we suggest a new protocol for the preoperative selection of palpable thyroid nodules.

Clinical assessment of collagen cross-linked N-telopeptides as a marker of bone metabolism in patients with primary hyperparathyroidism

This study assesses the clinical usefulness of collagen cross-linked N-telopeptides (NTx), a new marker for bone resorption, as a marker for primary hyperparathyroidism. The study was conducted on 114 patients who had undergone parathyroidectomy for primary hyperparathyroidism. Urine NTx levels were longitudinally determined by ELISA. Longitudinal serum bone Gla protein (BGP) determinations and dual energy X-ray absorptiometry (DEXA) examinations were also performed before and after parathyroidectomy. Before parathyroidectomy, the mean urine NTx level in primary hyperparathyroidism was 149.0 +/- 116.8 pmol BCE/mumol Cr (normal: < 55 pmol BCE/mumol Cr), and the positive rate was 88.5%. The mean BGP level was 33.5 +/- 59.1 ng/mL (normal: 12.7 ng/mL), and the positive rate was 77.7%. The NTx positive rate was higher than the BGP positive rate. NTx values were significantly correlated with bone mineral density (P < 0.002) and BGP values (P < 0.005). Two weeks after parathyroidectomy the NTx levels had already decreased significantly to 65.1 pmol BCE/mumol Cr (P < 0.001), and by one month postoperatively they had fallen to 55.9 pmol BCE/mumol Cr, reaching the normal range much sooner than BGP. The NTx normalization rate two weeks postoperatively was 37%, and by 12 months postoperatively it was normal in 83% of patients. BGP levels decreased more gradually than the NTx levels, and only became normal in 9% of cases two weeks postoperatively, as opposed to 74% by 12 months. It is concluded that NTx reflects bone turnover in primary hyperthyroidism, and that it is an excellent marker for bony lesions before and after parathyroidectomy.

Blood coagulation parameters in retinal arterial occlusion

BACKGROUND

Thromboembolism is considered a crucial event in the pathogenesis of retinal occlusion, resulting in a severe damage of central or peripheral visual function.

METHODS

We evaluated hemostatic system parameters in the plasma of 14 patients (11 males and 3 females aged 59-73 years) affected by acute retinal ischemia (central retinal arterial occlusion or arterial branch occlusion). The diagnosis of retinal arterial occlusion was established according to clinical symptoms, ophthalmoscopic findings and fluorescein angiography. In addition to routine coagulation tests, antithrombin III, prothrombin fragment 1+2 (F1+2), thrombin-antithrombin III complex (TAT), and D-dimer were measured in the plasma both at the moment of diagnosis (before therapy initiation) and 3-6 months later (at least 1 months after antithrombotic therapy discontinuation).

RESULTS

We found a marked increase in the plasma levels of F1+2, TAT, and D-dimer during the acute event, compared with healthy control values. F1+2 and TAT significantly decreased during follow-up, whereas D-dimer was unchanged.

CONCLUSION

Our data indicate accelerated conversion of prothrombin to thrombin (high F1+2) and an increase in circulating thrombin (high TAT) during retinal arterial occlusion, providing evidence that increased thrombin generation may play a role in acute retinal ischemia.

A percutaneous large-needle aspiration biopsy technique for histologic examination of the testis in infertile patients

OBJECTIVE

To describe a relatively new percutaneous large-needle aspiration biopsy technique for histologic examination of the testis in infertile patients.

DESIGN

Retrospective analysis of clinical and pathologic data.

SETTING

Clinical and academic research environment.

PATIENT(S)

Sixty-six infertile patients who underwent testicular biopsy.

INTERVENTION(S)

Local anesthesia was induced through spermatic cord block with lidocaine, and a relatively large needle (usually 18- or 20-gauge) was introduced percutaneously into the testicle without a scrotal incision.

MAIN OUTCOME MEASURE(S)

The number of seminiferous tubules per histologic section of each testicular biopsy sample.

RESULT(S)

A mean of 74 seminiferous tubules were obtained in the histologic sections of each biopsy sample. This number varied according to the size of the needle used; it was 24.7 when a 21-gauge needle was used, 56.2 when a 20-gauge needle was used, and 103 when an 18-gauge needle was used. The biopsies were performed in the office. No significant hematomas occurred, no antibiotic prophylaxis was prescribed, and no postbiopsy medical or pharmacologic interventions were required.

CONCLUSION(S)

Tissue specimens as large as those obtained with open surgical biopsy can be obtained from the testicles of infertile patients with the use of a percutaneous technique that is easier, less costly, and safer than any previously reported.

The role of tumour markers in predicting skeletal metastases in breast cancer patients with equivocal bone scintigraphy

Bone scintigraphy (BS) is commonly performed in the staging and postoperative monitoring of breast cancer. Nevertheless, due to low specificity it often demonstrates hot spots with equivocal interpretation, which may be misleading in the management of these patients. The aim of this study was to assess the value of a serum tumour marker panel in selecting among the patients with equivocal BS those with bone metastases. Between January 1986 and December 1995, 297 breast cancer patients were followed-up after mastectomy with serial determinations of a CEA-TPA-CA15.3 tumour marker panel, BS and liver echography. The tumour marker panel was used to select patients with equivocal BS for examination of suspicious bone areas by further imaging techniques. Up to December 1995, 158 (53%) patients showed an equivocal BS and 47 patients developed bone metastases. In the 158 patients with equivocal BS, prolonged clinical and imaging follow-up over 45 months (mean; range 12-120) was used to ascertain the presence or absence of bone metastases. In these 158 patients the negative predictive value and positive predictive value of the tumour marker panel to predict bone metastases was 97% and 75% respectively. This study shows that in breast cancer patients the CEA-TPA-CA15.3 tumour marker panel has a high value in selecting those patients with bone metastases, or at high risk of developing clinically-evident bone metastases, among the large number of subjects with equivocal BS.

Aspiration needle biopsy in preoperative selection of thyroid nodules defined at fine-needle aspiration as microfollicular lesions

The palpable thyroid nodules that are diagnosed as microfollicular by fine-needle aspiration cytologic analysis are usually excised for the low probability that the nodule is a well-differentiated follicular cancer. The authors retrospectively assess the use of aspiration needle biopsy (either 16- or 18-gauge needles) in the preoperative selection of the nodules diagnosed as microfollicular at fine-needle aspiration (either 20- or 22-gauge needles). Aspiration needle biopsy is a type of large needle biopsy that is a relatively easy and innocuous method of obtaining tissue fragments for preoperative histologic examination of palpable thyroid nodules. From 1980 through 1996, 6,314 patients with palpable thyroid nodules were examined by fine-needle aspiration; 29.5% of these nodules were also examined preoperatively by aspiration needle biopsy. Of all the patients with nodules, 6% received a fine-needle aspiration diagnosis of microfollicular nodule. Two hundred sixty of the 380 nodules (68%) that were diagnosed as microfollicular at fine-needle aspiration were also examined by aspiration needle biopsy; inadequate specimens were obtained in 17% of cases; pure microfollicular structure was confirmed by aspiration needle biopsy in 35% of the nodules; and aspiration needle biopsy showed the remaining 48% to contain a macrofollicular component suggesting a benign hyperplastic lesion. Seventeen nodules that were found to be microfollicular at fine-needle aspiration cytologic analysis and micromacrofollicular at aspiration needle biopsy were excised and the postoperative result was benign in all cases. Twenty-five nodules diagnosed as microfollicular either on both fine-needle aspiration and aspiration needle biopsy were excised and the postoperative diagnoses were benign (20 nodules) or malignant (5 nodules). These data indicate that aspiration needle biopsy can be used for preoperative selection of the nodules that are microfollicular at fine-needle aspiration by identifying the nodules with high probability of being malignant and thus contributing to the reduction in the number of surgical operations for benign nodules.

A multistep therapy with subcutaneous low dose recombinant interleukin-2, 5-fluorouracil and leucovorin prolongs the response of metastatic colorectal cancer patients: a pilot study

Data from 12 metastatic colorectal cancer patients who were submitted to a pilot study with a multistep subcutaneous (sc) low dose recombinant interleukin-2 (rIL-2), 5-fluorouracil (5-FU) and leucovorin (LV) administration were compared with those from 13 historical controls who were comparable for the major prognostic indices. All 12 patients in the pilot study were subjected initially to six to eight courses of 5-FU-LV by endovenous (ev) bolus consistent with the Machover schedule alternating with 6 weeks of rIL-2 cycles. At the progression of metastatic disease, the patients were given 500 mg/m2 per day of 5-FU by continuous infusion (ci) for 5 days every 4 weeks and in case of further progression, 2,600 mg/m2 of 5-FU by 24-h ci once a week for 6 weeks. The control patients were treated with 5-FU-LV by the Machover schedule until progression and then observed. As yet, two patients in the pilot study and three control patients are currently alive. In the pilot study, the patients' response rate (CR + PR) and overall response rate (CR + PR + SD) were much higher than in the controls (50 vs 23% and 92 vs 54%, respectively). Time duration of response and survival from primary surgery were more prolonged in the pilot study than in the historical control, although not significantly (10.5 vs 6 and 41.5 vs 29 months, respectively). Time from starting therapy to progression and survival from relapse were significantly in favour of the pilot study (11.5 vs 4 and 31 vs 13.5 months; P < 0.01 and P < 0.05 unpaired t-test, respectively). Low dose s.c. rIL-2 cycles were well tolerated and no interruption occurred. In the pilot study sporadic grade 3 toxicity (diarrhoea or leucopenia) was responsible for the reduction of 5-FU doses to 80% of the previous infusion, but no treatment was postponed. In conclusion, these preliminary data suggest the opportunity to initiate large prospective randomized trials using a multistep therapy with rIL-2, 5-FU ci at conventional and at high dose in metastatic colorectal cancer.

Large needle aspiration biopsy for reducing the rate of inadequate cytology on fine needle aspiration specimens from palpable thyroid nodules

From 1980 to 1996, 1,907 consecutive euthyroid subjects with palpable thyroid nodules were examined by fine needle aspiration (FNA) cytology plus large needle aspiration biopsy (LNAB) histology. There were 1,630 (85%) women and 277 (14.5%) men aged from 17 to 80 years. A single nodule was palpated in 1,419 subjects (74.4%) while 488 (25.6%) showed multiple nodules. The nodule size ranged between 1 and 7.5 cm. The number of inadequate specimens at the first examination, FNA cytology of LNAB histology, were 261 (13%) or 398 (20.8%), respectively. LNAB performed on the 261 nodules with nondiagnostic cytology showed findings which were adequate for diagnosis in 130 (49.8%) and inadequate in 131 (50.2%). Among the 261 patients with inadequate initial cytological findings 61 were subjected to repeated FNA and 36 repeated LNAB. More than 60% of the nodules on which FNA was repeated achieved a cytological diagnosis; more than 80% of the nodules reinvestigated by LNAB were finally diagnosed by histology. The mean nodule size was larger in the group with inadequate result than in that with adequate FNA or LNAB result. Among the 261 patients with inadequate cytological finding at the first FNA 28 were operated on; 20 were in the group with adequate LNAB histological findings and eight in the group with an inadequate LNAB. Two papillary cancers, one per group, were found at postoperative histology. However, one was diagnosed by LNAB and one at the second FNA. The remaining 26 nodules were all found to be benign postoperatively. This study shows that the addition of LNAB to FNA leads to a histological diagnosis in 50% of the palpable thyroid nodules with inadequate cytology at the first FNA and that LNAB can be used even for those nodules which remain uncharacterized after repeat FNA.

Uremic medium increases cytokine-induced PAI-1 secretion by cultured endothelial cells

The overall fibrinolytic activity is depressed in patients with chronic renal failure where a prothrombotic state is described, thereby enhancing the risk of vascular occlusive events. The mechanism responsible for fibrinolysis derangement has not yet been elucidated. To evaluate the effect of the uremic environment on the fibrinolytic activity of endothelial cells, we studied plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) production by human umbilical vein endothelial cells (HUVEC) in culture, exposed either to uremic or normal sera, before and after cytokine stimulation. Twenty uremics were studied: 11 were on conservative dietary treatment and nine were on maintenance hemodialysis. Eight healthy subjects served as controls. Before cytokine stimulation, no difference in the HUVEC supernatant concentration of t-PA and PAI-1 was found among the groups studied. After stimulation with interleukin (IL)-1 and tumor necrosis factor (TNF)-alpha, the HUVEC supernatant levels of PAI-1 in the uremics were higher than in the controls, whereas the supernatant levels of t-PA did not differ. Our data provide evidence that uremic serum, in concert with IL-1 or TNF-alpha, can enhance PAI-1 secretion by endothelial cells, thereby depressing the fibrinolytic system. This impaired endothelial fibrinolytic response to hypercoagulation could favor vascular events, which are the major cause of morbidity and mortality in patients with chronic uremia.

Comparison between plasma concentrations of testosterone, nitric oxide and endothelin 1-2 in penile and brachial venous blood: preliminary results in men with psychogenic impotence

In the present study venous plasma concentrations of testosterone (T), nitric oxide (NO) and endothelin 1-2 (ET1-2) in the flaccid penis and brachial blood were measured in men with psychogenic impotence. T and NO were significantly lower in the penile venous blood, while ET1-2 showed no statistical difference. These data support the hypothesis of testosterone dependence of penile nitric oxide synthesis (NOS).

Anti-D treatment for chronic immune thrombocytopenic purpura: clinical and laboratory aspects

We used low-dose anti-D immunoglobulins for home treatment of Rh+ adult patients with chronic immune thrombocytopenic purpura (ITP). After informed consent, 15 unselected outpatients (ten males and five females, aged 22 to 72), affected by chronic ITP with negative HIV test, were given intramuscular injection of 900-1500 micrograms of anti-Rh0 (D) IgG over 3 days every month for 2 or 3 consecutive months. Platelet count (mean +/- SD) significantly increased from basal value of 17,000 +/- 9,000/microL to 72,000 +/- 55,000/microL at the end of treatment. Eight patients achieved a rise in platelet count above 50,000/microL (five above 100,000/microL) and two of them maintained the increase longer than 6 months without further anti-D administration. Three patients responsive to the first cycle responded to further treatment with substantially identical results. Seven patients had no response. Four of them had not responded to previous glucocorticoid and intravenous IgG therapy. Direct antiglobulin test became strongly positive in all patients and mean serum haptoglobin decreased from a basal value of 118 +/- 59 to 61 +/- 43 mg/dL; nevertheless no clinically overt hemolysis was observed in any patient, there was no rise of serum indirect bilirubin and hemoglobin level was unchanged (mean +/- SD basal level 13.6 +/- 2.2 g/dL; after anti-D 13.9 +/- 1.2 g/dL). No hematoma developed at the injection site, and no other side effects occurred. Our results show that anti-D therapy is effective in the majority of patients well tolerated, and feasible as home treatment: thus it can be recommended as a cheap and safe alternative treatment in ITP Rh+ patients.

Natural anticoagulants, aging, and thromboembolism

The normal aging process alters blood coagulation system in humans; this may be of great concern in the view of the known association of vascular disease with advancing age. The plasma concentration of several coagulation factors, namely fibrinogen, factor VII, factor VIII, factor IX, high molecular-weight kininogen, and prekallikrein, increase in healthy humans, paralleling the physiological aging process. Plasma parameters of clotting activation in vivo, such as prothrombin fragment 1 + 2, fibrinopeptide A, thrombin-antithrombin III complex, and D-dimer, are positively correlated with age. Nevertheless, among centenarians, biochemical signs of marked hypercoagulability are associated with a healthy state. Natural anticoagulants, including antithrombin III, heparin cofactor II, protein C, protein S, and tissue factor pathway inhibitor, can modulate the reactions of blood coagulation system. The occurrence of menopause is accompanied by a significant increase in antithrombin III plasma level; the mean antithrombin III levels in older women exceed levels in male contemporaries. In healthy elderly subjects heparin cofactor II plasma concentrations are lower than in young subjects, independently of gender. Protein C levels raise with age in both sexes, as well as free protein S levels. In women, statistically significant increases in the plasma concentration of the tissue factor pathway inhibitor have been observed, whereas no significant age-related change has been found in men. The fact that many subjects with congenital defects of natural anticoagulants do not undergo thromboembolic events in young age suggests that in healthy individuals a raise in natural anticoagulants can balance the age-related increase of procoagulant factors.