The impact of parasites on marine mammals: a review

The design and implementation of conservation plans for marine mammals is a matter of public concern. However, very little is known about the role of parasites in the dynamics of marine mammal populations. This is probably due to methodological constraints concerning sampling biases, poor knowledge of the biology of the hosts and parasites and difficulty and costy of experimental studies. However, current evidence supports the theory that parasites may regulate marine mammal populations. Crassicauda species in cetaceans and Uncinaria lucasi in pinnipeds seem good candidates as regulating agents. In addition, parasite-induced mass mortalities may be important in marine mammal populations. Well documented cases are the PDV virus which decimated the European common seal (Phoca vitulina) populations in 1988 and the Mediterranean striped dolphin (Stenella coeruleoalba) morbillivirus infection of 1990-1992. Due to the social organisation patterns of marine mammals it is possible that such die-offs occur at very low densities, representing a potential threat to endangered species like the Mediterranean monk seal (Monachus monachus), the Hawaiian monk seal (M. schauinslandi) or the Finish Saimaa seal (Phoca hispida saimensis). It is concluded that parasites can play an important role in marine mammal populations not only at the ecological scale but at the evolutionary one too.

Reference ranges for the concentrations of total and complexed plasma prostate-specific antigen and their ratio in patients with benign prostate hyperplasia

OBJECTIVE

To establish the normal distribution and reference ranges of complexed and total prostate-specific antigen (PSA) and the complexed-to-total PSA ratio according to the age of the patients, so that PSA can be used to distinguish between prostate cancer and benign prostate hyperplasia (BPH).

MATERIAL AND METHODS

Using specific ELISAs, total PSA and PSA complexed to alpha 1-antichymotrypsin (complexed PSA) were determined in 237 BPH patients, 160 with histologically confirmed BPH and 77 in whom prostate cancer was excluded by digital rectal examination, transrectal ultrasound and total PSA measurement.

RESULTS

Both total and complexed PSA correlated with patient age (r = 0.424 and r = 0.379, p < 0.0001, respectively). However, no correlation was found between the complexed-to-total PSA ratio and age (r = 0.026, p > 0.2). The mean complexed-to-total PSA ratio for the 237 BPH patients was 0.69 +/- 0.11, and only 23 had a ratio > 0.8.

CONCLUSIONS

These results show that the cut-off point of 0.8 established for the complexed-to-total PSA ratio is the same for men of all ages, and that the use of this ratio may avoid many negative prostate biopsies, confirming that PSA: alpha 1ACT is a potential marker for differential diagnosis of prostate carcinoma and BPH.

Molecular epidemiology of Mycobacterium tuberculosis strains isolated during a 3-year period (1993 to 1995) in Seville, Spain

The genetic polymorphism of Mycobacterium tuberculosis strains isolated in Seville, Spain, was studied by using computer-assisted analysis of the IS6110 fingerprint in order to determine the current situation and to evaluate the human-to-human transmission of this pathogen. One hundred seventy-six isolates from 175 patients among the 205 patients diagnosed with tuberculosis (TB) during a 3-year period (1993 to 1995) were cultured and analyzed. One hundred nine patients (62%) were infected with genetically different isolates, and 67 isolates (38%) were grouped into 19 clusters. These results demonstrate that the level of clustering of strains in Seville is intermediate between those in developed and developing countries. Epidemiological relatedness was shown for isolates from only 10 of these clusters. Active and high transmission rates exist in children and in human immunodeficiency virus (HIV)-infected adults, while in non-HIV-infected adults this transmission rate is moderate. Although transmission from children to adults is uncommon, the probability of transmission from HIV-infected patients to young adults not infected with HIV may be higher. On the basis of these observations, we predict a constant rise in the rate of TB transmission among HIV-infected patients and probably in young adult patients not infected with HIV if measures for the effective prevention of TB among the HIV-infected population are not implemented.

Activated protein C resistance phenotype in patients with antiphospholipid antibodies

The effect of antiphospholipid antibodies (aPL) on the action of activated protein C (APC) was examined in 32 patients: 19 with lupus anticoagulant (LA), 6 with anticardiolipin antibodies (aCL), and 7 with LA and aCL. Eighteen patients had a ratio of activated partial thromboplastin time (APTT) with APC to APTT without APC (APTT ratio) <2.06 (cut-off level) and no factor V Leiden mutation; these patients showed APC-resistance (APC-R) phenotype. The mean prolongation of APTT after addition of APC in a control group was 45.3 seconds, with a lower limit of 31.4 seconds. Only 3 of the 18 patients with low APTT ratio had a prolongation of <31.4 seconds; they were classified as true APC-R phenotype, whereas the other 15 patients were classified as spurious APC-R. Of the 3 patients with true APC-R, 2 had deep venous thrombosis, 1 with pulmonary embolism, and the third had recurrent abortion. Of the other 15 patients, 2 had had ischemic stroke, 1 had recurrent abortion, and 12 were asymptomatic. Circulating APC level was measured in 14 of the 18 aPL patients with a low APTT ratio; it was lower than the normal lower limit in 4 patients and within the lower limit in 2. Three of the 4 patients with reduced APC levels had a history of thrombosis. We conclude that patients with aPL who show APC-R phenotype due to a low APTT ratio without the factor V Leiden mutation can be classified into two groups: true and spurious APC-R phenotype. Since those with true APC-R phenotype could have greater thrombotic risk, adequate classification of these patients is important. Moreover, aPL can sometimes interfere with the activation of protein C, thus reducing the circulating levels of APC, and this could constitute another thrombotic risk factor.

Modulatory effect of erythrocytes on the platelet reactivity to collagen in IDDM patients

Platelets participate in the atherothrombotic complications of diabetes. Recent data demonstrate that platelet reactivity can be modulated via cell-cell interactions with erythrocytes and neutrophils. In this study, platelet reactivity was evaluated in 30 IDDM patients. We used an analytical procedure that permits an independent evaluation of platelet activation (granule release, eicosanoid formation) and platelet recruitment (pro-aggregatory activity of cell-free releasates) after platelet stimulation with collagen in the presence or absence of other blood cells. The interaction between platelets and erythrocytes (hematocrit 40%) resulted in a marked enhancement of platelet activation (5HT, betaTG, TXA2 release) and recruitment in both patients and control subjects. The erythrocyte enhancement of platelet TXA2 synthesis and recruitment was significantly higher in the patients, while no differences were detected in platelet granule release. The elevated platelet recruitment in the IDDM patients was found to be due to 1) increased susceptibility of diabetic platelets to the prothrombotic effect of erythrocytes and 2) the greater response of diabetic platelets to their own cell-free releasate. Patients with poor metabolic control (elevated HbA1c) or longer evolution time had an even greater platelet recruitment. The presence of microalbuminuria is not related to the platelet recruitment. Since platelet recruitment is an essential step in thrombus growth, its enhancement may favor thrombotic complications in IDDM.

The effect of long-term treatment with hypotensive drugs on blood viscosity and erythrocyte deformability in patients with essential arterial hypertension

This study examined ninety-six patients with essential arterial hypertension (WHO grade I-II) who had been under treatment for a period of at least one year before participating in the study. When the study began the patients received no drug treatment for one month. At the end of this washout period their basal situation was evaluated and drug treatment was begun (26 patients on calcium antagonists, 39 on beta-blockers and 31 on angiotensin converting enzyme inhibitors). The patients were evaluated again after one and two years of uninterrupted treatment with the chosen medication. The results obtained indicate that in a basal situation hypertensive patients have higher blood viscosity and erythrocyte rigidity values than the control group. Regardless of the drug treatment used, the patients experienced during the study a progressive deterioration of their hemorheological situation consisting of an increase in red blood cell rigidity and increased blood viscosity. These results indicate the importance of evaluating the hemorheological parameters of hypertensive patients and suggest that it may be advisable to include in their treatment some kind of medication that prevents progressive rheological deterioration.

Diagnostic value of SCC, CEA and CYFRA 21.1 in lung cancer: a Bayesian analysis

The aim of this study was to evaluate the diagnostic value of three tumour markers, squamous cell carcinoma (SCC) antigen, carcinoembryonic antigen (CEA) and CYFRA 21.1, in lung cancer using a Bayesian analysis to obtain the predictive values for different pretest probabilities or prevalences. A cross-sectional study included 94 patients with lung cancer, 40 with benign lung disease, and 40 healthy controls. SCC antigen and CEA were measured in blood samples by microparticle enzyme immunoassay (MEIA), and CYFRA by enzyme-linked immunosorbent assay (ELISA). The results of tumour marker determinations were expressed as percentiles, and showed significantly higher levels in the cancer group than in the two control groups. Taking the 95th percentile of benign lung diseases as the cut-off point (specificity 95%), the following sensitivities were found: SCC 41%, CEA 31% and CYFRA 79%. After a Bayesian analysis, the best results for the three tumour markers were found in prevalences of 30-40%. The highest incremental gain was obtained by CYFRA (at prevalence of 36%, positive and negative predictive value approximately 90%). The three tumour markers were included in a stepwise regression analysis to predict lung cancer, and CYFRA was the only selected variable. We conclude that CYFRA 21.1 may be a useful marker in lung cancer when there is an intermediate pretest probability of disease.

[False tuberculosis outbreak caused by specimen contamination in a micro-bacteriology laboratory: confirmation by molecular techniques]

BACKGROUND

The authors describe a false outbreak of tuberculosis by contamination in sample processing.

METHODS

The longitudinal polymorphisms of restriction fragments (RFLPs) of 6 strains of Mycobacterium tuberculosis isolated in different patients over a three week period and which were apparently implicated in an outbreak of tuberculosis were analyzed.

RESULTS

Four of the strains studied presented identical restriction pattern and the remaining two presented totally different patterns. Following study of the clinical histories and the epidemiologic relationships three cases of tuberculosis were confirmed. The other three strains isolated corresponded to contamination during the sampling process.

CONCLUSIONS

In a possible outbreak of six cases of tuberculosis, molecular techniques have allowed identification of three true cases of tuberculosis and have demonstrated contamination during the sampling process in three other cases. The latter could not have been shown with the clinical and phenotypical data of the strains.

Diagnostic value of SCC, CEA and CYFRA 21.1 in lung cancer: a Bayesian analysis

The aim of this study was to evaluate the diagnostic value of three tumour markers, squamous cell carcinoma (SCC) antigen, carcinoembryonic antigen (CEA) and CYFRA 21.1, in lung cancer using a Bayesian analysis to obtain the predictive values for different pretest probabilities or prevalences. A cross-sectional study included 94 patients with lung cancer, 40 with benign lung disease, and 40 healthy controls. SCC antigen and CEA were measured in blood samples by microparticle enzyme immunoassay (MEIA), and CYFRA by enzyme-linked immunosorbent assay (ELISA). The results of tumour marker determinations were expressed as percentiles, and showed significantly higher levels in the cancer group than in the two control groups. Taking the 95th percentile of benign lung diseases as the cut-off point (specificity 95%), the following sensitivities were found: SCC 41%, CEA 31% and CYFRA 79%. After a Bayesian analysis, the best results for the three tumour markers were found in prevalences of 30-40%. The highest incremental gain was obtained by CYFRA (at prevalence of 36%, positive and negative predictive value approximately 90%). The three tumour markers were included in a stepwise regression analysis to predict lung cancer, and CYFRA was the only selected variable. We conclude that CYFRA 21.1 may be a useful marker in lung cancer when there is an intermediate pretest probability of disease.

Prothrombotic effects of erythrocytes on platelet reactivity. Reduction by aspirin

BACKGROUND

Aspirin effectively reduces the incidence of secondary vascular occlusive events in only 25% of patients. Low-dose aspirin as currently used blocks platelet production of prothrombotic thromboxane A2 and allows endothelial synthesis of antithrombotic prostacyclin. This regimen minimizes gastrointestinal toxicity. We previously showed that intact erythrocytes markedly enhance platelet reactivity. Therefore we investigated whether supplementation of low-dose aspirin with a single high dose at 2-week intervals could more effectively block erythrocyte promotion of platelet reactivity.

METHODS AND RESULTS

Effects of different aspirin regimens on erythrocyte enhancement of platelet reactivity in normal volunteers were measured with the use of an assay that evaluates both platelet activation and recruitment. After 15 days of daily ingestion of 50 mg aspirin, reactivity of platelets alone was inhibited. However, erythrocyte promotion of platelet activation and recruitment was only inhibited by approximately 50% and persisted in the total absence of thromboxane synthesis. In contrast, if 50 mg/d aspirin was preceded by a single loading dose of 500 mg aspirin, the erythrocyte prothrombotic effect was strongly inhibited (approximately 90%) for 2 to 3 weeks. However, over time, erythrocytes "escaped" from this inhibition, and once again became prothrombotic, even on a daily regimen of 50 mg aspirin.

CONCLUSIONS

For clinical purposes, we recommend a loading dose of aspirin (500 mg), followed by daily administration of 50 mg. The loading dose should be repeated at 2-week intervals. This regimen blocks recovery of the erythrocyte capacity to promote platelet reactivity and may amplify the therapeutic potential of aspirin in cardiovascular disease.

Heparin stimulation of the inhibition of activated protein C and other enzymes by human protein C inhibitor--influence of the molecular weightof heparin and ionic strength

The ability of unfractionated (UF) heparin and low-molecular-weight heparin (LMWH) to potentiate the inhibition of fibrinolytic and coagulation factors by protein C inhibitor (PCI) was studied. Inhibition of activated protein C (APC), urokinase plasminogen activator (uPA), tissue plasminogen activator (tPA), thrombin, factor Xa (Xa), factor XIa (XIa) and plasma kallikrein (KK) by PCI was found to be dependent on the size of the polysaccharide. In general, maximal stimulation was reached with UF heparin, except in the case of KK. Differences in heparin stimulation were more pronounced for thrombin, APC, uPA, tPA and XIa, whereas inactivation of Xa by PCI was less dependent on the presence of heparin, and kallikrein showed higher potentiation with LMWH than with UF heparin. The second-order rate constants for enzyme inhibition by PCI were strongly dependent on the ionic strength, and, in general, with an ionic strength higher than 0.15 the heparin stimulation of the inhibition reactions was drastically reduced. These results may explain the large discrepancies in the literature on the effect of heparin on the stimulation of enzyme inhibition by PCI. They also show that LMWH is less efficient in stimulating the PCI inhibition of APC, uPA and tPA, which could contribute to the antithrombotic effect of these enzymes.

Decreased expression of PAI-2 mRNA and protein in pregnancies complicated with intrauterine fetal growth retardation

An increase in plasma plasminogen activator inhibitors (PAIs), fundamentally PAI type 2 (PAI-2), has been described in normal pregnancy probably because the placenta is the main source of the high plasma levels of this protein. Although we have previously described plasmatic alterations of these inhibitors in pregnancies complicated with intrauterine fetal growth retardation (IUGR), no reports have been published about placental PAI-2 mRNA expression. In the present study, the placental PAI-2 expression determined in pregnancies complicated with IUGR and in severe preeclamptic patients was compared with that of normal pregnancies in order to identify the placental cell types expressing PAI-2 and to determine whether the production of PAI-2 is altered in placentas from IUGR. In situ hybridization analyses show that the syncytiotrophoblasts are the cells with the greatest PAI-2 expression in placenta. We report that the significant decrease in plasma and placental PAI-2 levels in IUGR groups is fundamentally due to a diminished expression of PAI-2 mRNA in placenta.

Abnormal expression of plasminogen activator inhibitors in patients with gestational trophoblastic disease

We previously reported significantly elevated levels of plasminogen activator inhibitor type 1 (PAI-1) in plasma and placenta from pregnant women with severe pre-eclampsia, and pre-eclampsia is a frequent problem in molar pregnancies. As increases in PAI-1 may contribute to the placental alterations that occur in pre-eclampsia, we have begun to investigate changes in PAI-1 as well as PAI-2 and several other components of the fibrinolytic system in patients with trophoblastic disease. Significant increases in plasma PAI-1 and decreases in plasma PAI-2 levels were observed in molar pregnancies when compared with the levels in normal pregnant women of similar gestational age. PAI-1 antigen levels also were increased, and PAI-2 levels were decreased in placenta from women with molar pregnancies compared with placenta obtained by spontaneous abortion. Immunohistochemical analysis revealed strong positive and specific staining of PAI-1 in trophoblastic epithelium in molar pregnancies and relatively weak staining of PAI-2. No association between the distribution of PAI-1 and vitronectin was found, and no specific signal for tissue type PA, urokinase type PA, tumor necrosis factor-alpha, or interleukin-1 was detected. In situ hybridization revealed an increase in PAI-1 but not PAI-2 mRNAs in placenta from molar pregnancies in comparison with placenta from abortions. These results demonstrate increased PAI-1 protein and mRNA in trophoblastic disease and suggest that localized elevated levels of PAI-1 may contribute to the hemostatic problems associated with this disorder.

Effect of HMG-CoA reductase inhibitors on red blood cell membrane lipids and haemorheological parameters, in patients affected by familial hypercholesterolemia

Eighteen patients with familial hypercholesterolemia treated with lovastatin (40 mg/day) for three months were studied to find out whether the drug induces modifications in the lipid composition of the erythrocyte membrane and whether these induce changes in the rheological behaviour of the red blood cell. Our results show that the changes observed in plasma lipids correlate with a significant decrease in the cholesterol/phospholipid ratio of the red blood cell membrane. These changes in the lipid composition of the cell are statistically related to a decrease in the erythrocyte aggregability and an improvement in blood filterability probably due to an increase in the red blood cell deformability.

Hemorheological profile in patients with cardiovascular risk factors

In order to find out whether hemorheological alterations precede the atherosclerotic lesions and could constitute an atherothrombotic risk factor, we studied the hemorheological profile in 150 healthy normotensive offspring whose parents were diagnosed as having essential hypertension WHO I-II grade and in another group of 40 children with familial hypercholesterolemia (FH) but without vascular atherosclerosis lesions, whose parents also suffer from FH. In offspring of hypertensive individuals, a significant increase in the fibrinogen level with respect to the control group was found both in males and females. In addition, only the female offspring showed a higher leucocyte count. FH children showed increased erythrocyte aggregation and increased plasma viscosity with respect to the control group. The fact that the rheological alterations appear prior to the development of the vascular lesion suggests that they could play a role in the pathogenesis of the atherosclerotic process.

Erythrocyte membrane cholesterol/phospholipid changes and hemorheological modifications in familial hypercholesterolemia treated with lovastatin

Fourteen patients with familial hypercholesterolemia treated with lovastatin (40 mg/day) for three months were studied to find out whether the expected changes in plasma lipids are accompanied by modifications in the lipid composition of the erythrocyte membrane and whether these in turn induce changes in the rheological behavior of the red blood cell. Our results demonstrate the efficacy of lovastatin in reducing the plasma concentration of cholesterol and LDL cholesterol. The changes observed in the plasma lipids correlate with a significant decrease in the cholesterol/phospholipid ratio of the red blood cell membrane, from 1.19 +/- 0.19 in a basal situation to 0.92 +/- 0.23 (p < 0.01) at the end of treatment. These changes in the lipid composition of the cell are statistically related to a decrease in erythrocyte aggregability and an improvement in blood filterability, which means beneficial change in the patients' hemorheological situation.

A modification of the APC resistance test and its application to the study of patients on coumarin therapy

APC resistance appears to be caused, predominantly, by a mutation in coagulation factor V (nucleotide 1691: G to A). This phenomenon is usually studied by performing APTTs in the absence and presence of added APC. We studied a modification of the assay involving dilution of the test plasma in factor V deficient plasma, to render the assay more factor V specific. This modification was applied to 76 patients with venous thrombosis on coumarin treatment and to 45 controls. Two out of 45 controls (4.4%) showed abnormal results with the modified test. They also showed loss of factor V exon 10 Mnl I restriction site, associated to APC resistance. All remaining controls, with normal functional results by the modified assay, showed normal restriction profile. We detected 9 affected patients (11.8%), one of them homozygous or double heterozygous. In conclusion, the modified assay is very sensitive for factor V dependent APC resistance, and can successfully be applied to patients on coumarin therapy.

Comparative in-vitro activity of sparfloxacin against genital pathogens

The in-vitro activity of sparfloxacin against four pathogens commonly implicated in genital infections was compared with that of a number of other commonly administered antimicrobials. Sparfloxacin demonstrated excellent activity against Neisseria gonorrhoeae (MIC range of < or = 0.0002-5 mg/L for beta-lactamase producing strains, and < or = 0.0002-0.03 mg/L for non-beta-lactamase producing strains). This activity was similar to that of lomefloxacin and ciprofloxacin and was greater than that of ofloxacin. Sparfloxacin was more active against Ureaplasma urealyticum (MIC90 1 mg/L) than the other three quinolones (MIC90 4 mg/L). Sparfloxacin was much more active against Mycoplasma hominis (MIC90 0.06 mg/L) than the other quinolones (MIC90 1 mg/L). Sparfloxacin showed the most potent inhibitory and bactericidal activity of the quinolones against Chlamydia trachomatis with MIC and MBC of 0.06 mg/L (ofloxacin MIC and MBC 1 mg/L; ciprofloxacin and lomefloxacin MIC and MBC 2 mg/L). The results of this study and others performed by workers using different methods are consistently similar. Since sparfloxacin has broad activity against pathogens implicated in genital infections it may be a good therapeutic alternative for these syndromes.

Sinus Venous Thrombosis Associated with a Nephrotic Syndrome in an Eight-Year-Old Child

The nephrotic syndrome (NS) is reportedly as sociated with an increased risk of thromboembolic dis ease. We describe the case of an 8-year-old child with a steroid-responsive NS who developed a longitudinal si nus venous thrombosis. No family thrombophilic ten dency was found. To our knowledge, this is the second case published with these clinical characteristics. We sug gest that the sinus venous thrombosis was precipitated by the low levels of antithrombin III and hypoalbuminemia. Moreover, steroids probably played an etiological role. Key Words: Nephrotic syndrome—Sinus venous throm bosis—Venous thrombosis—Antithrombin III.

Quantification of circulating activated protein C in human plasma by immunoassays--enzyme levels are proportional to total protein C levels

We have developed a simple assay that measures the circulating activated protein C (APC) in plasma. The assay requires collection of duplicate blood samples, one in citrate plus heparin and the other in citrate plus inhibitors of the enzyme. In the heparin tube, APC reacts completely and irreversibly with its major plasma inhibitors, protein C inhibitor (PCI) and alpha 1-antitrypsin (alpha 1AT), and the complexes formed are measured by ELISAs. The amount of circulating APC is calculated from the difference between the total amount of complexed APC (sample in citrate plus heparin) and the amount of APC complexed in vivo (sample in citrate plus inhibitor). Over 95% of the APC added to blood collected with heparin was recovered in the assay. The assay can easily be performed in four hours, and had a detection limit of 0.1 ng/ml APC. The mean APC level in 18 protein C heterozygous members from seven kindreds was significantly lower (0.6 +/- 0.3 ng/ml) than in 20 healthy controls (1.1 +/- 0.3 ng/ml) (p < 0.001), whereas the mean level in 10 non-affected members from the kindreds studied was 1.5 +/- 0.3 ng/ml. In the group of 12 nonanticoagulated heterozygous protein C-deficient individuals, the three patients with a history of venous thrombosis had a mean APC level significantly lower than the nine asymptomatic members (p < 0.01), both subgroups showing similar protein C levels. There was a significant correlation in all groups between the levels of APC and the levels of protein C antigen (r = 0.758, p < 0.0001) and activity (r = 0.745, p < 0.0001), which means that APC circulating levels are proportional to protein C levels and suggests that the protein C level is the limiting factor in the rate of protein C activation in vivo.