Biochemical assessment of myocardial fibrosis in hypertensive heart disease

Fibrous tissue accumulation is an integral feature of the adverse structural remodeling of cardiac tissue seen with hypertensive heart disease. Given the importance of fibrous tissue in leading to myocardial dysfunction and failure, noninvasive monitoring of myocardial fibrosis by use of serological markers of collagen turnover could prove a clinically useful tool, particularly given the potential for cardioprotective and cardioreparative pharmacological strategies. An emerging experimental and clinical experience holds promise for the use of radioimmunoassays of various serological markers of fibrillar collagen type I and type III turnover in arterial hypertension. More specifically, the measurement of serum concentrations of procollagen type I C-terminal propeptide (a peptide that is cleaved from procollagen type I during the synthesis of fibril-forming collagen type I) may provide indirect diagnostic information on both the extent of myocardial fibrosis and the ability of antihypertensive treatment to diminish collagen type I synthesis and reduce myocardial fibrosis. This approach represents an exciting and innovative strategy, and available data set the stage for larger trials, in which noninvasive measures of fibrosis in hypertensive heart disease could prove useful.

[The Mycobacteria Growth Indicator Tube (MGIT) is useful for anticipating the resistance of Mycobacterium tuberculosis to rifampicin but not to isoniazid]

A previously proposed MGIT protocol was assessed focussing on its reliability to test the mainstay antituberculous drugs. Isoniazid (H) (0.1 mg/l) and rifampin (R) (1 mg/l) were assayed against 109 Mycobacterium tuberculosis isolates affecting patients at high risk of multidrug-resistant tuberculosis. All isolates were simultaneously tested on Löwenstein-Jensen medium by the proportion method considered the gold standard. MGIT readings were accomplished within 2 and 22 days after inoculation, at day 10, 93.4% of the tests were completed. Unsatisfactory to evaluate H activity, the assay misclassified 8.8% (5/57) H susceptible and 7.7% (4/52) H resistant isolates. Otherwise, it yielded correct results for all 60 R susceptible isolates and 93.9% (46/49) R resistant isolates. Properly backed-up by a conventional test and targeting high risk patients, the MGIT system proved to be a useful aid to anticipate most of resistance to R. Accuracy, cost and turnaround time were competitive compared with those of semi-automated culture-based or molecular methods.

Effect of different treatments on the evolution of polyamines during refrigerated storage of eggplants

The applicability of a thermal treatment was compared with modified-atmosphere (MA) storage in relation to chilling injury (CI) and polyamines evolution in eggplants. Fruits underwent physiological disorders at 3 degrees C, evidenced by the appearance of surface injuries at the third day of storage, and, after moving the fruits to 20 degrees C, by increased respiratory activity and more intense ethylene production. Storage of fruits in sealed low-density polyethylene bags and a previous treatment with heated air (1 h at 35 degrees C) were both effective in retarding chilling injury, though the former was better. Two free polyamines were found in cv. Black Nite: putrescine, in greater proportion, and spermidine. Putrescine increased in control (untreated) fruits stored at 3 degrees C in parallel with the external appearance of chilling injury, whereas this increase was either not exhibited or retarded in treated or MA stored fruits. Spermidine did not change in control fruits at 3 degrees C, remaining almost constant over the whole storage period, whereas in heat- and MAP-treated fruits spermidine levels exhibited a decrease.

N-acetyl-L-cysteine improves renal medullary hypoperfusion in acute renal failure

This study evaluated the effects of N-acetyl-L-cysteine (NAC), a free radical scavenger, and N(omega)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide (NO) synthesis inhibitor, on the changes in renal function, intrarenal blood flow distribution (laser-Doppler flowmetry), and plasma peroxynitrite levels during the acute renal failure (ARF) produced by inferior vena cava occlusion (IVCO; 45 min) in anesthetized rats. Renal blood flow fell on reperfusion (whole kidney by -45.7%; cortex -58.7%, outer medulla -62.8%, and papilla -47.7%); glomerular filtration rate (GRF) also decreased (-68.6%), whereas fractional sodium excretion (FE(Na%)) and peroxynitrite and NO/NO plasma levels increased (189.5, 46.5, and 390%, respectively) after ischemia. Pretreatment with L-NAME (10 microg. kg(-1). min(-1)) aggravated the fall in renal blood flow seen during reperfusion (-60%). Pretreatment with NAC (150 mg/kg bolus + 715 microg. kg(-1). min(-1) iv) partially prevented those changes in renal function (GFR only fell by -29.2%, and FE(Na%) increased 119.4%) and laser-Doppler blood flow, especially in the outer medulla, where blood flow recovered to near control levels during reperfusion. These beneficial effects seen in rats given NAC seem to be dependent on the presence of NO, because they were abolished in rats pretreated with L-NAME. Also, the antioxidant effects of NAC prevented the increase in plasma peroxynitrite after ischemia. In conclusion, NAC ameliorates the renal failure and the outer medullary vasoconstriction induced by ICVO, effects that seem to be dependent on the presence of NO and the scavenging of peroxynitrite.

Role of guanylyl cyclase and cytochrome P-450 on renal response to nitric oxide

The present study evaluated whether inhibition of guanylyl cyclase (GC) with 1H-(1,2,4)oxadiazolo[4,3-a]quinoxaline-1-one (ODQ) and methylene blue (MB) or inhibition of the renal metabolism of arachidonic acid by cytochrome P-450 (CYP450) enzymes with 1-aminobenzotriazole (ABT) and N-hydroxy-N'-(4 butyl-2-methyl phenyl)formamidine (HET0016) alters the renal tubular and vascular effects of a nitric oxide (NO) donor in vivo. Intrarenal infusion of ODQ or MB at a dose of 170 nmol. kg(-1). min(-1) lowered renal blood flow (RBF) by 30 and 15%, respectively; glomerular filtration rate (GFR) by 26 and 18%, respectively; and sodium and water excretion by approximately 35%. In rats pretreated with nitro-L-arginine methyl ester (37 nmol. kg(-1). min(-1)) to block the endogenous production of NO, intrarenal infusion of the NO donor S-nitroso-N-acetylcysteine (S-NO-NAC; 50 nmol. kg(-1). min(-1)) increased RBF (18%), sodium (73%), and water excretion (61%). ODQ or MB administration blocked the effect of S-NO-NAC on RBF but not the diuretic and natriuretic response. Pretreatment of rats with ABT or HET0016 also abolished the renal vasodilatory response to the NO donor and reduced its diuretic and natriuretic effect. These results indicate that both activation of GC and inhibition of CYP450 enzymes contribute to the renal vascular actions of NO, whereas the natriuretic and diuretic actions of NO appear to be largely CYP450 dependent.

Usefulness of serum carboxy-terminal propeptide of procollagen type I in assessment of the cardioreparative ability of antihypertensive treatment in hypertensive patients

BACKGROUND

We investigated whether serum concentration of carboxy-terminal propeptide of procollagen type I (PIP), a marker of collagen type I synthesis, can be used to assess the ability of antihypertensive treatment to regress myocardial fibrosis in hypertensive patients.

METHODS AND RESULTS

The study was performed in 37 patients with essential hypertension and hypertensive heart disease. After randomization, 21 patients were assigned to losartan and 16 patients to amlodipine treatment. At baseline and after 12 months, right septal endomyocardial biopsies were performed to quantify collagen volume fraction (CVF) on picrosirius red-stained sections with an automated image-analysis system. Serum PIP was measured by specific radioimmunoassay. Nineteen patients in the losartan group and 11 in the amlodipine group finished the study. Time-course changes in blood pressure during treatment were similar in the 2 groups of patients. In losartan-treated patients, CVF decreased from 5.65+/-2.03% to 3.96+/-1.46% (P<0.01) and PIP from 127+/-30 to 99+/-26 microgram/L (P<0.01). Neither CVF or PIP changed significantly in amlodipine-treated patients. CVF was directly correlated with PIP (r=0.44, P<0.001) in all hypertensives before and after treatment.

CONCLUSIONS

These findings suggest that the ability of antihypertensive treatment to regress fibrosis in hypertensives with biopsy-proven myocardial fibrosis is independent of its antihypertensive efficacy. Our data also suggest that blockade of the angiotensin II type 1 receptor is associated with inhibition of collagen type I synthesis and regression of myocardial fibrosis in hypertensives. Thus, determination of serum PIP may be useful to assess the cardioreparative properties of antihypertensive treatment in hypertensives.

Vertical distribution of fine root density, length density, area index and mean diameter in a Quercus ilex forest

We used minirhizotrons to determine the vertical distribution of fine roots in a holm oak (Quercus ilex L.) forest in a typical Mediterranean area over a 3-year period (June 1994-March 1997). We measured fine root density (number of roots per unit area), fine root length density (length of roots per unit area), fine root area index (area of roots per unit area) and fine root mean diameter. Variables were pooled for each 10-cm depth interval to a depth of 60 cm. Fine roots tended to decrease with increasing depth except between 0 and 10 cm, where the values of all fine root variables were less than in the 10-cm stratum below. Fine root vertical distribution was compared with soil water content and soil temperature at different depths in the soil profile.

[Genetics and molecular biology in cardiology (IV). Myocardial response to biomechanical stress]

Biomechanical stress of the myocardium is the situation resulting from hypoxia, hypertension, and other forms of myocardial injury, that invariably lead to increased demands for cardiac work and/or loss of functional myocardium. As a consequence of biomechanical stress a number of responses develop involving all the myocardial cells, namely cardiomyocytes. As a result some myocardial phenotypic changes develop that are initially compensatory (i.e., hypertrophy) but which may mediate the eventual decline in myocardial function that occurs with the transition from hypertrophy to failure in conditions of persistent stress (i.e., apoptosis and fibrosis). This review focuses on the steps involved in the response of the myocardium to biomechanical stress and highlights the most recent developments in the molecular mechanisms involved in the development of heart failure.

[Biochemical diagnosis of hypertensive myocardial fibrosis]

A substantial increase in fibrillar collagen has been observed in the left cardiac ventricle of animals and humans with arterial hypertension. Hypertensive myocardial fibrosis is the result of both increased collagen types I and III due to the fact that its synthesis by fibroblasts and myofibroblasts is stimulated and its extracellular collagen degradation unchanged or decreased extracellular collagen degradation. Hemodynamic and non-hemodynamic factors may be involved in the disequilibrium between collagen synthesis and degradation that occurs in hypertension. As shown experimentally and clinically, an exaggerated rise in fibrillar collagen content promotes abnormalities of cardiac function, contributes to the decrease in coronary reserve and facilitates alterations in the electrical activity of the left ventricle. Although microscopic examination of cardiac biopsies is the most reliable method for documenting and measuring myocardial fibrosis, the development of non-invasive methods to indicate the presence of myocardial fibrosis in hypertensive patients would be useful. We have therefore applied a biochemical method based on the measurement of serum peptides derived from the tissue formation when synthesized and degradation of fibrillar collagens to monitor the turnover of these molecules in rats with spontaneous hypertension and patients with essential hypertension.

Effects of antihypertensive agents on the left ventricle: clinical implications

Hypertensive heart disease (HHD) is characterized by left ventricular hypertrophy (LVH), alterations of cardiac function, and coronary flow abnormalities. LVH is an independent cardiovascular risk factor related to cardiovascular complications in patients with hypertension. Therefore, a decrease in left ventricular mass is a therapeutic goal in these patients. The effect of the different antihypertensive agents on LVH regression has been studied in nearly 500 clinical trials. Most studies conclude that there is regression of LVH after significant decrease in blood pressure with most commonly prescribed antihypertensive agents. However, the ability to regress LVH is different between antihypertensive drug classes. ACE inhibitors and calcium channel antagonists are more potent in reducing left ventricular mass than beta-blockers, with diuretics falling in the intermediate group. Recent data suggest that angiotensin AT(1) receptor antagonists reduce left ventricular mass to a similar extent as ACE inibitors or calcium channel antagonists. Although a large number of studies have established that reversal of LVH decreases the occurrence of adverse cardiovascular events in patients with hypertension, the hypothesis that LVH regression is beneficial has not yet been conclusively proven. On the other hand, the time has come to revisit the current management of HHD simply focused on controlling blood pressure and reducing left ventricular mass. In fact, it is necessary to develop new approaches aimed to repair myocardial structure and protect myocardial perfusion and function and, in doing so, to reduce in a more effective manner, adverse risk associated with HHD. The identification of genes involved in both the process of HHD and the response to therapy may be critical for the development of these new approaches. This article will review briefly the available data on the effects of antihypertensive agents on HHD. In addition, the emerging new concepts on the pharmacology of hypertensive myocardial remodeling and the pharmacogenetic basis of the treatment of HHD will be also considered.

Mechanisms of increased susceptibility to angiotensin II-induced apoptosis in ventricular cardiomyocytes of spontaneously hypertensive rats

Previous findings have shown that hypotensive doses of losartan prevent the excess of apoptosis present in the hypertrophied left ventricle of adult spontaneously hypertensive rats (SHR). This study was designed to determine whether angiotensin II facilitates apoptosis in cardiomyocytes of adult SHR. Primary cultures of ventricular cardiomyocytes from 30-week-old normotensive Wistar-Kyoto rats (WKY) and SHR with left ventricular hypertrophy were exposed to 10(-)(9) mol/L angiotensin II for 24 hours. Apoptotic cells were assessed by terminal deoxynucleotidyl transferase assay and confirmed by Annexin V detection. The expression of Bax-alpha, Bcl-2, p53, and caspase-3 proteins was assessed by Western blot assays. The expression of BAX gene was assessed by Northern blot. Angiotensin II increased (P<0.01) cardiomyocyte apoptosis, and this effect was higher (P<0.001) in SHR cells than in WKY cells. Whereas losartan (10(-7) mol/L) blocked the apoptotic effect of the octapeptide in cells from the two strains of rats, PD123319 (10(-7) mol/L) inhibited angiotensin II-mediated apoptosis only in SHR cells. Angiotensin II stimulated (P<0.01) Bax-alpha protein, and this effect was higher (P<0.01) in SHR cells than in WKY cells. Angiotensin II did not modify Bcl-2, p53, and BAX mRNA in cells from the two strains of rats. Angiotensin II induced a similar increase (P<0.05) in the ratio caspase-3/procaspase-3 (an index of caspase-3 activation) in cardiomyocytes from the two strains of rats. The present in vitro results indicate that SHR cardiomyocytes exhibit enhanced susceptibility to angiotensin II-induced apoptosis. Ligand binding to angiotensin II type 1 and type 2 receptors leading to changes in posttranscriptional processing of Bax-alpha and accumulation of this proapoptotic protein may be involved in the abnormal response of SHR cardiomyocytes. These data support a role for angiotensin II in apoptosis observed in the left ventricle of these rats.

Synthesis of vinyl- and alkynylcyclopentanetetraols by SmI2/Pd(0)-promoted carbohydrate ring-contraction

A variety of vinyl- or alkynyl-substituted polyhydroxylated cyclopentanes and cyclobutanes are prepared in enantiomerically pure form from appropriate carbohydrate precursors, in a direct one-step ring-contraction procedure promoted by SmI2 and catalytic Pd(O). This reaction is thought to proceed through intermediate ring-opened allyl- or allenylsamarium complexes that undergo ring-closure by intramolecular carbonyl addition. A predominant trans relationship is found between vinyl (or alkynyl) and hydroxyl groups at the two newly created stereogenic centers, with good to excellent levels of stereoselectivity being observed in the formation of homopropargyl cyclopentanol products. Under appropriate conditions, preparatively useful yields are realized of stereoisomers not directly available using alternative methodology.

Chronic AT(1) blockade stimulates extracellular collagen type I degradation and reverses myocardial fibrosis in spontaneously hypertensive rats

It has been suggested that left ventricular fibrosis in spontaneously hypertensive rats (SHR) is the result of both exaggerated collagen synthesis and insufficient collagen degradation. We have shown previously that chronic treatment with the angiotensin II type 1 receptor antagonist losartan results in diminished synthesis of collagen type I molecules and reversal of myocardial fibrosis in SHR. This study was designed to investigate whether losartan also affects the extracellular degradation of collagen type I fibers in the left ventricle of SHR. The study was performed in 30-week-old normotensive Wistar-Kyoto rats (WKY), untreated SHR, and SHR treated with orally administered losartan (20 mg/kg per day) for 14 weeks before they were killed. Ventricular collagenase activity was determined by degradation of [(14)C]collagen with tissue extracts. Ventricular expression of tissue inhibitor of metalloproteinases 1 (TIMP-1) mRNA was analyzed by Northern blot. A histomorphometric study of the left ventricle was performed in all rats. Compared with WKY, SHR exhibited left ventricular hypertrophy, increased (P<0.05) blood pressure, left ventricular collagen volume fraction and TIMP-1 mRNA, and diminished (P<0.05) collagenase activity. After the treatment period, blood pressure was higher (P<0.05) in losartan-treated SHR than in WKY, and no significant differences were noted in the remaining parameters between the 2 strains of rats. Compared with untreated SHR, treated SHR showed no left ventricular hypertrophy, diminished (P<0.05) blood pressure, left ventricular collagen volume fraction and TIMP-1 mRNA, and increased (P<0.05) collagenase activity. These results suggest that the transcription of the TIMP-1 gene is upregulated in the hypertrophied and fibrotic left ventricle of adult SHR. Upregulation of TIMP-1 may account for diminished collagenase activity in the myocardium of those rats. Chronic angiotensin II type 1 receptor blockade with losartan resulted in inhibition of TIMP-1 expression and stimulation of collagenase activity in the left ventricle of SHR. It is proposed that angiotensin II may facilitate myocardial fibrosis in SHR by depressing the collagenase-mediated extracellular degradation of collagen fibers.

Attention and joint attention in preschool children with autism

Three experiments examined the role of attention in explaining dyadic (child-adult) and triadic (child-adult-object) joint attention difficulties in autism. Experiments 1 and 2 investigated children's ability to orient to an adult's attention bid and to follow the direction of a human or nonhuman cue. Experiment 3 tested ability to disengage and shift attention to objects. Results showed autism-specific difficulties at both dyadic and triadic levels. Children with autism were less responsive than developmentally delayed controls in orienting to attention bids and in following a human head-turn cue yet had no difficulty in shifting attention and were faster overall in orienting to targets. Results suggest a specific developmental delay in which children with autism rely on the presence of objects in the visual field to guide action. The relation between this problem and autistic children's difficulties with human communicative signals is discussed.

Serum carboxy-terminal propeptide of procollagen type I is a marker of myocardial fibrosis in hypertensive heart disease

BACKGROUND

This study was designed to investigate whether the serum concentration of the carboxy-terminal propeptide of procollagen type I (PIP), a marker of collagen type I synthesis, is related to myocardial fibrosis in hypertensive patients.

METHODS AND RESULTS

The study was performed in 26 patients with essential hypertension in which ischemic cardiomyopathy was excluded after a complete medical workup. Right septal endomyocardial biopsies were performed in hypertensive patients to quantify collagen content. Collagen volume fraction (CVF) was determined on picrosirius red-stained sections with an automated image analysis system. The serum concentration of PIP was measured by specific radioimmunoassay. Compared with normotensives, both serum PIP and CVF were increased (P<0.001) in hypertensives. A direct correlation was found between CVF and serum PIP (r=0.471, P<0.02) in all hypertensives. Histological analysis revealed the presence of 2 subgroups of patients: 8 with severe fibrosis and 18 with nonsevere fibrosis. Serum PIP was higher (P<0.05) in patients with severe fibrosis than in patients with nonsevere fibrosis. Using receiver operating characteristic curves, we observed that a cutoff of 127 microg/L for PIP provided 78% specificity and 75% sensitivity for predicting severe fibrosis with a relative risk of 4.80 (95% CI, 1.19 to 19.30).

CONCLUSIONS

These results show a strong correlation between myocardial collagen content and the serum concentration of PIP in essential hypertension. Although preliminary, these findings suggest that the determination of PIP may be an easy and reliable method for the screening and diagnosis of severe myocardial fibrosis associated with arterial hypertension.

Attention and joint attention in preschool children with autism

Three experiments examined the role of attention in explaining dyadic (child-adult) and triadic (child-adult-object) joint attention difficulties in autism. Experiments 1 and 2 investigated children's ability to orient to an adult's attention bid and to follow the direction of a human or nonhuman cue. Experiment 3 tested ability to disengage and shift attention to objects. Results showed autism-specific difficulties at both dyadic and triadic levels. Children with autism were less responsive than developmentally delayed controls in orienting to attention bids and in following a human head-turn cue yet had no difficulty in shifting attention and were faster overall in orienting to targets. Results suggest a specific developmental delay in which children with autism rely on the presence of objects in the visual field to guide action. The relation between this problem and autistic children's difficulties with human communicative signals is discussed.

Epidemiological study of Streptococcus pneumoniae carriers in healthy primary-school children

To obtain information on the Streptococcus pneumoniae carrier state in Spanish children, 332 healthy 6-year-old children from nine primary schools in northern Spain were screened. Thirty-six percent of the children had positive cultures yielding 128 strains. Seventy-one strains belonged to 14 serogroup/serotypes, the most frequent being 19, 23, 3, 24 and 11. Fifty-seven strains were nontypeable. The identification of strains with equivocal results was confirmed at species level by means of hybridisation with a specific probe, pneumolysin-mediated agglutination and a pathogenicity test in mice. Sixty-four percent of strains showed resistance to penicillin, 22% of these also being resistant to cefotaxime. More than 40% of the strains were resistant to trimethoprim-sulfamethoxazole, tetracycline and erythromycin. Twenty percent of the erythromycin-resistant strains were susceptible to clindamycin. Two strains were resistant to rifampicin and one strain was resistant to ofloxacin. All strains were susceptible to vancomycin. Previous antibiotic administration and having siblings under the age of 2 years correlated with the carriage of pneumococcus. There was no correlation with the carriage of antibiotic-resistant strains, or a record of previous infections, previous hospital admissions or having relatives with chronic respiratory disease.

Comparative analysis of quantification of viral load in patients infected with hepatitis C virus: quantiplex HCV RNA assay and amplicor monitor assay

OBJECTIVE

two standardized techniques, Quantiplex HCV RNA 2.0 (bDNA) and Amplicor Monitor, were evaluated for the quantification of hepatitis C virus (HCV) load. Our objectives were: 1) to determine the relationship between viral load and genotype, and 2) to evaluate viral load in serial serum samples and in patients with normal or slightly elevated liver enzyme values in an area with a high prevalence of genotype 1.

RESULTS

the viral loads detected with the two methods correlated significantly (r = 0.7, p < 0.0001), but viral load was smaller with the Monitor than with the Quantiplex assay, and was independent of genotype. The Monitor/Quantiplex ratio was lower in patients with a non-1 genotype than in patients with genotype 1b. Virological characteristics were similar in patients with normal or slightly elevated enzyme levels and in patients with elevated enzyme values. Neither method showed a relationship between viral load and age, sex, duration of the infection, mode of transmission, or histological activity index.

CONCLUSION

viral load was not dependent on genotype. Measurement of viral load in a single serum sample adequately reflected the viral load measured in several serum samples from patients with chronic HCV infection. Patients with normal liver enzyme levels are not good candidates, in virological terms, for treatment with interferon.

Changes in polyamines and ethylene during the development and ripening of eggplant fruits (Solanum melongena)

The levels of free polyamines in the endocarpium of eggplants (Solanum melongena) cv. Black Nite were studied during fruit growth and ripening. Other parameters such as weight and volume variation, respiratory intensity, ethylene production, and sugar content were determined. The polyamines found were putrescine and spermidine, with a higher amount of the former. No spermine, agmatine, or cadaverine were found during the development and ripening period of eggplant. At the beginning of fruit development, the levels of putrescine and spermidine observed were 1.67 nmol/g of fresh tissue. Putrescine levels peaked at 17.4 nmol/g of fresh tissue on the ninth day after petal fall, decreasing later to the initial levels. No significant changes in spermidine were observed during the growth period of the fruit. Beginning 9 days after petal fall, there was a rapid increase in fruit weight and volume, which coincided with the maximum content of free polyamines. At the same growth stage, total sugar content was maximum. Ethylene production decreased rapidly from 14.23 to 1.5 microL/kg.h and remained low during the whole growth period.

Plants used in Guatemala for the treatment of protozoal infections. I. Screening of activity to bacteria, fungi and American trypanosomes of 13 native plants

Extracts were prepared from 13 native plants used for the treatment of protozoal infections. Activity against bacteria and fungi was demonstrated by dilution procedures; Trypanosoma cruzi was evaluated in vitro against epimastigote and trypomastigotes and in vivo against trypomastigotes. In active extracts, toxicity was evaluated by Artemia salina nauplii, oral acute toxicity (1-5 g/kg) and oral and intraperitoneal subacute toxicity in mice (500 mg/kg). From the plants screened, six showed activity (< or = 2 mg/ml) against bacteria, three against yeasts, five against Microsporum gypseum and five against T. cruzi in vitro and/or in vivo. In vitro and in vivo activity was demonstrated by Neurolaena lobata and Solanum americanum; in vitro or in vivo activity was shown by Acalypha guatemalensis, Petiveria alliacea and Tridax procumbens. Toxicity studies showed that extracts from S. americanum are toxic to A. salina (aqueous, 160 ppm). None showed acute or oral toxicity to mice; S. americanum showed intraperitoneal subacute toxicity.

Rapid screening tests for determining in vitro susceptibility of herpes simplex virus clinical isolates

The susceptibility of human herpes simplex virus (HSV) to acyclovir (ACV) was determined with the use of a single dose of the drug (1 and 2 micrograms of ACV per ml for HSV-1 and HSV-2, respectively) in two rapid assays: a rapid cytopathic effect inhibitory assay (Rapid CIA) and a rapid dye uptake assay (Rapid DUA). These tests allow the simultaneous determination of virus titer and susceptibility to ACV at a determined viral concentration (100 50% tissue culture infective doses and 100 50% dye uptake units). These tests were compared with a conventional susceptibility assay (dye uptake assay) and showed similar results. Indeterminate results with the Rapid CIA appeared in 3 of 30 samples. With the use of both Rapid CIA and Rapid DUA, we were able to determine the susceptibility of 100% of the isolates. The rapid tests, unlike conventional assays, are able to provide susceptibility results within 3 days after the virus has been isolated from a clinical specimen and could thus play a direct role in therapeutic decisions.

Soft salt-mannitol agar-cloxacillin test: a highly specific bedside screening test for detection of colonization with methicillin-resistant Staphylococcus aureus

The early detection of colonization with methicillin-resistant Staphylococcus aureus (MRSA) of patients in intensive-care units is an essential step in the strategy for preventing MRSA epidemics. In this study, tubes containing soft salt-mannitol agar with cloxacillin (6 microg/ml) (SSMAC) were prepared for inoculation of clinical samples at patients' bedsides by personnel of an intensive-care unit. A total of 1,914 swabs from different sample sites of 81 patients were dipped into SSMAC tubes, and after 24 h of incubation (in an incubator located near the intensive-care unit), an evident color change was considered by the intensive-care-unit personnel to be an MRSA alarm. Sixty-three (3.3%) SSMAC tubes were considered positive for MRSA, 1,827 (95.4%) were considered negative, and 24 (1.2%) were considered intermediate. Compared with values for parallel conventional surveillance cultures for MRSA, excluding tubes with intermediate results, the SSMAC test had a sensitivity of 72.7%, a specificity of 99.2%, a positive predictive value of 76.2%, and a negative predictive value of 99.0%. When intermediate tubes were considered positive, the corresponding values were 75.3, 98.2, 63.2, and 99.0%, respectively. The sensitivity and specificity values of the test to identify MRSA-colonized patients were 89.4 and 100%, respectively. Oropharyngeal and naris specimens were the most reliable samples for MRSA detection. False-negative results were frequent in bronchial aspirates with low (< 10(3) to 10(6) CFU/ml) MRSA counts. False-positive results were mainly due to methicillin-resistant Staphylococcus haemolyticus. The SSMAC tube is a useful, rapid, and inexpensive tool for the early identification of MRSA-colonized patients and, consequently, for the implementation of measures to prevent the spread of MRSA.