Reaction of tetracycline with biologically relevant chloramines

Helicobacter pylori (H. pylori) infection triggers inflammatory processes with the consequent production of hypochlorous acid (HOCl), monochloramine (NH₂Cl), and protein-derived chloramines. As the therapy for eradicating H. pylori is partially based on the use of tetracycline, we studied the kinetic of its consumption elicited by HOCl, NH₂Cl, N-chloro-n-butylamine (NHCl-But, used as a lysine-derived chloramine model), and lysozyme-derived chloramines. In the micromolar concentration range, tetracycline reacted rapidly with HOCl, generating in the first few seconds intermediates of short half-life. In contrast, a slow tetracycline consumption was observed in the presence of high NH₂Cl and NHCl-But concentrations (millimolar range). Similar chlorinated products of tetracycline were identified by mass spectrometry, in the presence of HOCl and NH₂Cl. These results evidenced that tautomers of tetracycline are pivotal intermediates in all reactions. In spite of the low reactivity of chloramines towards tetracycline, it is evident that, in the concentration range where they are produced in a H. pylori infection (millimolar range), the reactions lead to oxidation and/or chlorination of tetracycline. This kind of reactions, which were also observed triggered by lysozyme-derived chloramines, could limit the efficiency of the tetracycline-based therapy.

Prevalence and risk factors for postpartum depression among women with preterm and low-birth-weight infants: a systematic review

BACKGROUND

Although much is known about the risk factors for postpartum depression (PPD), the role of giving birth to a preterm or low-birth-weight infant has not been reviewed systematically.

OBJECTIVE

To review systematically the prevalence and risk factors for PPD among women with preterm infants.

SEARCH STRATEGY

Medline, CINAHL, EMBASE, PsycINFO and the Cochrane Library were searched from their start dates to August 2008 using keywords relevant to depression and prematurity.

SELECTION CRITERIA

Peer-reviewed articles were eligible for inclusion if a standardised assessment of depression was administered between delivery and 52 weeks postpartum to mothers of preterm infants.

DATA COLLECTION AND ANALYSIS

Data on either the prevalence of PPD or mean depression score in the target population and available comparison groups were extracted from the 26 articles included in the review. Risk factors for PPD were also extracted where reported.

MAIN RESULTS

The rates of PPD were as high as 40% in the early postpartum period among women with premature infants. Sustained depression was associated with earlier gestational age, lower birth weight, ongoing infant illness/disability and perceived lack of social support. The main limitation was that most studies failed to consider depression in pregnancy as a confounding variable.

AUTHOR'S CONCLUSIONS

Mothers of preterm infants are at higher risk of depression than mothers of term infants in the immediate postpartum period, with continued risk throughout the first postpartum year for mothers of very-low-birth-weight infants. Targeted clinical interventions to identify and prevent PPD in this vulnerable obstetric population are warranted.

Dose-response effect of Red Maca (Lepidium meyenii) on benign prostatic hyperplasia induced by testosterone enanthate

The main goal of this study was to determine the effect of a freeze-dried aqueous extract of the red variety of Lepidium meyenii (Red Maca) on testosterone-induced benign prostatic hyperplasia (BPH) in adult rats of the Holtzman strain. Rats were treated with freeze-dried aqueous extract of Red Maca at doses of 0, 0.01, 0.05, 0.1, and 0.5 g/kg body wt. A positive control group received Finasteride (0.6 mg/kg body wt.). After treatment, the animals were sacrificed, and the ventral prostate was extracted, and weighed. HPLC was used to determine the presence of glucosinolates in Red Maca. The prostate weight diminished in a dose-dependent fashion in rats treated with Red Maca. The effect of Red Maca was better than that observed with Finasteride. Finasteride, but not Red Maca, reduced seminal vesicles weight. Analysis of the HPLC indicated the presence of benzyl glucosinolate (Glucotropaeolin) with a content of 0.639%. Serum testosterone levels were not affected by Red Maca. Moreover, serum testosterone levels were not related to prostate or seminal vesicles weight in rats treated with vehicle and Red Maca. In conclusion, Red Maca administered orally in rats seems to exert an inhibitory effect at a level post DHT conversion, on the BPH-induced experimentally, although a direct measure of reductase action would still be required.

Simulated laparoscopy using a head-mounted display vs traditional video monitor: an assessment of performance and muscle fatigue

BACKGROUND

The direction of visual gaze may be an important ergonomic factor that affects operative performance. We designed a study to determine whether a head-mounted display (HMD) worn by the surgeon would improve task performance and/or reduce muscle fatigue during a laparoscopic task when compared to the use of a traditional video monitor display (VMD).

METHODS

Surgical residents (n = 30) were enrolled in the study. A junior group, consisting of 15 postgraduate year (PGY) = 1 subjects with no previous laparoscopic experience, and a senior group, consisting of 15 PGY 4 and PGY 5 subjects with experience, completed a laparoscopic task that was repeated four times using the Computer Enhanced Laparoscopic Training System (CELTS). Groups alternated between using the HMD with the task placed in a downward frontal position and the VMD with the task at a 30 degrees lateral angle. The CELTS module assessed task completion time, depth perception, path length of instruments, response orientation, motion smoothness; the system then generated an overall score. Electromyography (EMG) was used to record sternocleidomastoid muscle activity. Display preference was surveyed.

RESULTS

The senior residents performed better than the junior residents overall on all parameters (p < 0.05) except for motion smoothness, where there was no difference. In both groups, the HMD significantly improved motion smoothness when compared to the VMD (p < 0.05). All other parameters were equal. There was less muscle fatigue when using the VMD (p < 0.05). We found that 66% of the junior residents but only 20% of the senior residents preferred the HMD.

CONCLUSIONS

The CELTS module demonstrated evidence of construct validity by differentiating the performances of junior and senior residents. By aligning the surgeon's visual gaze with the instruments, HMD improved smoothness of motion. Experienced residents preferred the traditional monitor display. Although the VMD produced less muscle fatigue, inexperienced residents preferred the HMD, possibly because of improved smoothness of motion.

Effect of high altitude exposure on spermatogenesis and epididymal sperm count in male rats

The present study was designed to determine the effect of exposure to high altitude on spermatogenesis using transillumination technique and sperm count in male rats. In addition, the effect of oral intubation for intragastric administration of vehicle on testicular parameters in adult male rats in a schedule of 42 days was assessed. Male rats were exposed to Cerro de Pasco (Peru) at 4340 m for 3, 7, 14, 21, 28, 35 and 42 days resulting in a modification of the pattern of the seminiferous tubule stages. At day 3, stages I, IV-V, VI, VII and IX-XI were relatively shorter at high altitude than at sea level. At day 7, stages VIII, IX-XI, XII and XIII-XIV were reduced. At day 14, stages VII, VIII and IX-XI were reduced. At day 21 and 28, stages VIII, XII and XIII-XIV were significantly increased at high altitude. At day 35 an increase in stage XIII-XIV was observed. At day 42, stages II-III, IX-XI and XII were significantly increased at high altitude. Epididymal sperm count was significantly reduced at day 7 of exposure to high altitude and maintained low levels with respect to sea level up to 42 days. In conclusion, high altitude exposure affects spermatogenesis, particularly onset of mitosis and spermiation. This in turn affects epididymal sperm count.

Effect of Lepidium meyenii (Maca) on spermatogenesis in male rats acutely exposed to high altitude (4340 m)

Lepidium meyenii (Maca) is a Peruvian hypocotyl that grows exclusively between 4000 and 4500 m in the central Andes. Maca is traditionally employed in the Andean region for its supposed fertility-enhancing properties. The aim of this study was to test the hypothesis that Maca can prevent high altitude-induced testicular disturbances. Adult male rats were exposed for 21 days to an altitude of 4340 m and treated with vehicle or aqueous extract of Maca (666.6 mg/day). The lengths of the stages of the seminiferous epithelium and epididymal sperm counts were obtained at 0, 7, 14 and 21 days of exposure. The stages of the seminiferous tubules were assessed by transillumination. A dose-response study was also performed at sea level to determine the effect of Maca given to male rats at doses of 0, 6.6, 66.6 and 666.6 mg/day for 7 days on body weight, seminiferous tubule stages and epididymal sperm count. The length of stage VIII and the epididymal sperm count were increased in a dose-dependent manner in Maca-treated rats but treatment reduced the length of stage I. At the highest dose, sperm count increased 1.58 times, the length of stage VIII increased 2.4 times and the length of stage I was reduced 0.48 times compared with the value at dose 0. Exposure to high altitude resulted in a reduction in epididymal sperm count after 7 days and lower values were maintained up to 21 days. Altitude reduced spermiation (stage VIII) to half and the onset of spermatogenesis (stages IX-XI) to a quarter on days 7 and 14 but treatment with Maca (666.6 mg/day) prevented these changes. Data on transillumination and epididymal sperm count in the Maca-treated group exposed to high altitude were similar to those obtained at sea level. Maca increased the sperm count on day 21 of exposure to high altitude to values similar (1095.25 +/- 20.41x10(6) sperm, means +/- S.E.M.) to those obtained in the Maca-treated group at sea level (1132.30 +/- 172.95x10(6) sperm). Furthermore, in the Maca-treated group exposed for 21 days to high altitude, epididymal sperm count was higher than in the non-treated group at sea level (690.49 +/- 43.67x10(6) sperm). In conclusion, treatment of rats with Maca at high altitude prevented high altitude-induced spermatogenic disruption.

Intraoperative ultrasound and prophylactic ursodiol for gallstone prevention following laparoscopic gastric bypass

BACKGROUND

Previous studies have shown that ursodiol decreases gallstone formation from 32% to 2% following open gastric bypass, but no data exist on laparoscopic Roux-en-Y gastric bypass (LRYGB) using intraoperative ultrasound (IOUS) screening.

METHODS

LRYGB with IOUS were performed on 195 consecutive patients. Patients with gallstones underwent simultaneous cholecystectomy, and patients without gallstones were prescribed ursodiol, 300 mg twice daily, for 6 month. Follow-up survey and ultrasound.

RESULTS

Of 195 patients, 44 (23%) had had a prior cholecystectomy, 21 (11%) underwent a simultaneous cholecystectomy, 129 (66%) had gallbladders left intact, and one (0.5%) false negative IOUS was excluded. Of 69 patients with ultrasound and survey follow-up (mean, 10 months), 19 (28%) developed gallstones seven with symptoms), and 50 (72%) were gallstone free. Forty-one percent of patients were compliant with ursodiol. There was no difference in compliance between patients with and without gallstones. In patients with gallstones, all of the symptomatic patients were noncompliant, whereas none of the compliant patients developed symptoms. Medication side-effects occurred in 17 of 69 patients (25%).

CONCLUSIONS

IOUS during LRYGB efficiently screens for gallstones, and selective cholecystectomy followed by prophylactic ursodiol results in low morbidity. Improvements in compliance may lower the incidence of postoperative gallstone formation.

Low-grade parasitaemias and cold agglutinins in patients with hyper-reactive malarious splenomegaly and acute haemolysis

A cluster of 16 cases of hyper-reactive malarious splenomegaly (HMS) with severe, acute haemolysis, from an isolated, Venezuelan, Yanomami population, was prospectively investigated. Nine (69%) of the 13 HMS sera investigated but only one (7%) of 14 control sera (P < 0.005) contained elevated titres (of at least 1:32) of complement-fixing IgM cold agglutinins (CA). The CA detected had specificity for both the I and i blood-group antigens (with a relative predominance of anti-I) and wide thermal stability. The mean reciprocal CA titre was much higher for the HMS sera than for the control samples (59.16 v. 2.28; P < 0.001). Indirect tests for antiglobulin were positive for two of the 13 HMS cases (but none of 14 controls) investigated; all of the direct tests for antiglobulin gave negative results. The seven HMS cases checked, using an assay based on a nested PCR which amplified species-specific ribosomal sequences from Plasmodium vivax or P. falciparum, each yielded the PCR product that indicated P. vivax infection. However, only six (25%) of the 24 control samples (collected, at the same time as the HMS samples, from asymptomatic adults from the same Yanomami population) were PCR-positive (P < 0.001). In some cases at least, the acute severe episodes of haemolysis occasionally seen in HMS appear to be associated with an auto-immune, cold-agglutinin-mediated response triggered by non-patent parasitaemias.

Laparoscopic surgery in the elderly patient

BACKGROUND

Elderly patients represent a unique surgical challenge because of the associated complex comorbidity and diminished cardiopulmonary reserve. Therefore, minimally invasive surgery in the elderly may have a larger impact compared to the younger population. The aim of this study was to prospectively evaluate the experience of laparoscopic surgery in patients >or=70 years of age in our unit.

METHODS

Two hundred and thirty-two patients (34 females and 98 males) older than 70 years who underwent various elective and emergency laparoscopic procedures between 1992 and 1997 were assessed prospectively. Preoperative comorbidity, operative results, and postoperative outcomes were analyzed.

RESULTS

The median age of the patients was 76 years. The majority of patients were ASA class II. The mean hospital stay was 3.4 days. The overall morbidity and mortality rates were 10.8% and 3.4% respectively, and the conversion rate was 4.3%.

CONCLUSIONS

Our experience suggests that laparoscopic surgery in the elderly is safe, is associated with short hospital stay, and produces less morbidity and mortality. Therefore, it should be adopted widely if the expertise in the area of laparoscopic surgery is available for this group of patients.

High prevalence of GB virus C/hepatitis G virus genotype 3 among autochthonous Venezuelan populations

GB virus C or hepatitis G virus (GBV-C/HGV) is highly prevalent among population groups at risk of parenterally transmitted viral agents, but it has also a worldwide distribution in other non-risk population groups. GBV-C/HGV RNA and antibodies against its envelope protein (anti-E2 Abs) were found in 3/86 (3%) and 7/89 (8%) of biomedical science personnel (BSP), in 31/453 (7%) and 37/200 (19%) of blood donors (BD), and in 6/64 (9%) and 26/59 (44%) of hemodialysis patients (HD) from Caracas, Venezuela. A significant gradient of GBV-C/HGV exposure (anti-E2 Abs and/or GBV-C/HGV RNA) was found between BSP (lowest prevalence), BD, and HD (P < 0.001). GBV-C/HGV RNA and anti-E2 Abs were also found in 2/69 (2.9%) and 2/44 (4.5%) of individuals from a rural community, in 9/162 (5.5%) and 2/40 (5%) of West Amerindians, and in 14/56 (25%) and 4/53 (7.5%) of South Amerindians. Socioeconomic and cultural factors may have contributed to the relatively high risk of exposure to GBV-C/HGV in BD and Amerindians. Whereas GBV-C/HGV genotypes 1 (n = 1), 2 (n = 6), and 3 (n = 22) were present in Venezuela, only the Asiatic genotype 3 was found infecting Amerindians and rural populations (n = 16). Genotype assignment based on the 5' noncoding region of the GBV- C/HGV genome was corroborated in some isolates by genetic analysis of the E2 region. This report confirms the circulation of the Asiatic genotype of GBV-C/HGV among Amerindians, suggesting an old origin of GBV-C/HGV. This might be associated with the apparently low pathogenesis of this virus.

Artemisinin antimalarials in pregnancy: a prospective treatment study of 539 episodes of multidrug-resistant Plasmodium falciparum

The emergence and spread of multidrug-resistant Plasmodium falciparum compromises the treatment of malaria, especially during pregnancy, where the choice of antimalarials is already limited. Artesunate (n=528) or artemether (n=11) was used to treat 539 episodes of acute P. falciparum malaria in 461 pregnant women, including 44 first-trimester episodes. Most patients (310 [57.5%]) received re-treatments after earlier treatment with quinine or mefloquine. By use of survival analysis, the cumulative artemisinin failure rate for primary infections was 6.6% (95% confidence interval, 1.0-12.3), compared with the re-treatment failure rate of 21.7% (95% confidence interval, 15.4-28.0; P=.004). The artemisinins were well tolerated with no evidence of adverse effects. Birth outcomes did not differ significantly to community rates for abortion, stillbirth, congenital abnormality, and mean gestation at delivery. These results are reassuring, but further information about the safety of these valuable antimalarials in pregnancy is needed.

Randomized comparison of quinine-clindamycin versus artesunate in the treatment of falciparum malaria in pregnancy

In areas where multidrug-resistant Plasmodium falciparum (MDR-Pf) is prevalent, only quinine is known to be safe and effective in pregnant women. On the western border of Thailand, 7 days of supervised quinine (30 mg/kg daily) cures two-thirds of P. falciparum-infected women in the 2nd and 3rd trimesters of pregnancy. Artesunate is effective against MDR-Pf and the limited data on its use in pregnancy suggest it is safe. An open randomized comparison of supervised quinine (10 mg salt/kg every 8 h) in combination with clindamycin (5 mg/kg every 8 h) for 7 days (QC7) versus artesunate 2 mg/kg per day for 7 days (A7) was conducted in 1997-2000 in 129 Karen women with acute uncomplicated falciparum malaria in the 2nd or 3rd trimesters of pregnancy. There was no difference in the day-42 cure rates between the QC7 (n = 65) and A7 (n = 64) regimens with an efficacy of 100% in both, confirmed by parasite genotyping. The A7 regimen was also associated with less gametocyte carriage; the average person-gametocyte-weeks for A7 was 3 (95% CI 0-19) and for QC7 was 39 (95% CI 21-66) per 1000 person-weeks, respectively (P < 0.01). There was no difference in gastrointestinal symptoms between the groups but there was significantly more tinnitus in the QC7 group compared to the A7 group (44.9% vs 8.9%; RR 5.1; 95% CI 1.9-13.5; P < 0.001). The favourable results with quinine-clindamycin mean that there is a useful back-up treatment for women with falciparum malaria who experience quinine and artesunate failures in pregnancy. Adherence to the 7-day regimen and cost (US$18.50 per treatment) are likely to be the main obstacles to this regimen.

Effect of Lepidium meyenii (maca) roots on spermatogenesis of male rats

AIM

To determine the effect of oral administration of an aqueous extract from the roots of Lepidium meyenii (maca) on spermatogenesis in adult male rats.

METHODS

Male rats received an aqueous extract of the root (66.7 mg in one mL) twice a day for 14 consecutive days.

RESULTS

Treatment with Lepidium meyenii resulted in an increase in the weights of testis and epididymis but not the seminal vesicle weight. The length and frequency of stages IX-XIV seminiferous tubules, where mitosis occurred, were increased and stages I-VI were reduced in rats treated with Lepidium meyenii.

CONCLUSION

The Lepidium meyenii root invigorates spermatogenesis in male rats by acting on its initial stages (IX-XIV).

Hepatitis delta virus genotypes I and III circulate associated with hepatitis B virus genotype F In Venezuela

The genotypes of hepatitis B (HBV) and delta (HDV) viruses circulating among Venezuelan Amerindian populations, where these viruses are endemic, were determined by sequencing of PCR amplified products from HBsAg positive sera. HDV genotype I (n = 7, 6 from West Amerindians), and III (n = 5, 4 from South Amerindians), were found. Only one HDV genotype I isolate was associated with HBV genotype D, 4 HDV genotype I and 2 HDV genotype III infected individuals were co-infected with HBV genotype F. The failure to detect the South American HDV genotype III in West Amerindians might be related to the outbreak of fulminant hepatitis with high mortality rate occurred between 1979 and 1982, probably affecting more the Amerindians infected with HDV genotype III. These results suggest the circulation of HDV genotype I among Amerindians, probably introduced through European immigrations, and that this HDV genotype is able to replicate in association with HBV genotype F.

Oral quinine pharmacokinetics and dietary salt intake

OBJECTIVES

The objective was to determine whether or not dietary salt intake affects the relative bioavailability of oral quinine. Salt intake has been shown to alter quinidine bioavailability.

METHODS

The pharmacokinetic properties of oral quinine sulphate (600 mg salt) were investigated in seven healthy Caucasian volunteers, in a randomised, crossover study, on low- and high-salt diets. Plasma quinine concentrations were measured by high-performance liquid chromatography (HPLC) and the 24-h urinary sodium excretion was assayed.

RESULTS

Although the 24-h urine sodium excretion was significantly higher when the volunteers were on a high-salt diet, there were no significant differences in quinine AUC0-infinity, tmax, and Cmax after the two diets. The median (range) quinine elimination half-life was significantly shorter after a high-salt diet [8.5 (4.3-10.2) h] than after a low-salt diet [10.0 (7.6-14.8) h] (P = 0.04).

CONCLUSION

Dietary salt does not affect the relative oral bioavailability of quinine sulphate.

Prevalence of infection with hepatitis C virus in Venezuela, as assessed with an immuno-assay based on synthetic peptides

Information on infection with hepatitis C virus (HCV) in South America is scarce. The seroprevalences of antibodies to HCV among urban, rural and Amerindian populations from Venezuela, and the genotypes of the HCV isolates recovered, were therefore determined. A total of 2592 sera were tested with an immuno-assay which was developed in-house and based on synthetic peptides. Each reactive sample was then re-tested, using other enzyme immuno-assays and a reverse-transcription, nested PCR, and any sample confirmed positive (in any test) was considered HCV-positive. Genotypes were determined by analysis of RFLP. Overall, 39 (1.5%) of the samples were found HCV positive. The results of the immuno-assays indicated that the seroprevalence of HCV markers among the Amerindians investigated (23/1082, or 2.1%) was significantly higher than that among the other subjects (16/1510, or 1.1%; P = 0.02). No such difference was observed in the numbers of subjects confirmed positive by PCR, however (6/1082 v. 10/1510), and some of the anti-HCV reactivity observed among Amerindians may have been the result of cross-reactivity with parasitic infections. The relative low prevalence of active HCV infection (16/2582, or 0.6%) and the HCV genotypes observed (mainly genotype 1) are in agreement with the results of previous studies indicating that HCV is not autochthonous to South America. However, it is clear that the virus may now be found even in isolated Amerindian populations. The in-house, synthetic-peptide-based immuno-assay seems to be a valuable tool for epidemiological studies.

Spur cell anaemia and acute haemolysis in patients with hyperreactive malarious splenomegaly. Experience in an isolated Yanomamo population of Venezuela

A prospective study, aimed to investigate the aetiology of an unusual clustering of cases of severe acute haemolytic anaemia affecting a high percentage of the adult population, was carried out in two isolated Yanomamo communities of the Upper Orinoco basin in Venezuela. Twenty-six patients with active or recent episodes of severe haemolysis were evaluated. All of them exhibited massive liver and spleen enlargement and fulfilled the diagnostic criteria of the hyperreactive malarious splenomegaly (HMS) syndrome. In four cases with advanced non-alcohol-related chronic liver disease, hypersplenism, severe haemolytic anaemia and acanthocytosis, the characteristic clinical and laboratory findings of spur cell anaemia were documented. Chronic infection by the HBV and HCV was present in three of them. However, in most of the 22 additional HMS cases, the acute haemolytic condition appeared associated with the occurrence of a cold agglutinin-mediated autoimmune response. The clustering of a significant number of cases of severe acute haemolysis in HMS patients from this small isolated aboriginal community is most unusual, and represents a serious complicating factor for a population already beleaguered by a high prevalence of malaria due to multiresistant strains of Plasmodium falciparum. Moreover, the coexistence of HMS and severe chronic HBV or HCV infection may further aggravate the course of the haemolytic disorder, because of the occurrence of spur cell anaemia.

Parasitological indicators of onchocerciasis relevant to ivermectin control programmes in the Amazonian focus of Southern Venezuela

In the previous paper it was concluded that those aged > or = 15 years of both sexes could comprise the indicator group for rapid epidemiological assessment (REA) of onchocerciasis in the Amazonian focus. This paper explores relationships between community microfilarial (mf) prevalence, intensity, and nodule prevalence in 20 Yanomami communities, that would allow identification of REA methods in the region. The mean nodule ratio (prevalence of nodules/prevalence of mf) was 0.54 when onchocercomata in the indicator group were considered. The Spearman correlation coefficient between mf and nodule prevalence was 0.686 (P = 0.001). Palpation of nodules had 92 % specificity and 32 % sensitivity when compared to skin-snipping for the diagnosis of onchocerciasis. The predictive value positive increased from 75 % to 81 % when the indicator group was used. A microfilarial prevalence > 75 % in this group would be indicative of hyperendemic status in the village, between 30 and 75 % of mesoendemicity, and < 30 % of hypoendemicity. For the assessment of infection intensity, biopsies may be taken from the iliac crest for all endemicity levels. Five of the hyperendemic villages surveyed in this work had a community microfilarial load (CMFL) greater than 10 mf/skin snip; the remaining 5 had a CMFL between 5 and 9. These levels of infection merit high priority ivermectin treatment. In Latin America, communities at both moderate and severe risk are included in mass chemotherapy programmes (i.e. when mf prevalence is over 20 %). Roughly, a nodule prevalence in the indicator group > 10 % would suggest a community mf prevalence > 20 % with a sensitivity of 85 % and a specificity of 71 %. A multiple linear regression model of the arc-sine transformed mf prevalence in the village (all ages) on nodule prevalence in those aged > or = 15 years and altitude of the village explained 72 % of the variance. The model combining nodule and altitudinal information had a sensitivity of 92 % and a specificity of 71 % in comparison to an estimated mf prevalence of 21 % or more. It is suggested that the usefulness of the REA methods proposed be assessed in other areas of the Amazonian onchocerciasis focus.

Artemether-lumefantrine for the treatment of multidrug-resistant falciparum malaria

The efficacy and safety of the 6-dose regimen of artemether-lumefantrine were assessed in an open randomized trial in children and adults presenting with acute, uncomplicated Plasmodium falciparum malaria in Thailand between November 1997 and March 1998. 200 patients were enrolled in 2 centres: 150 received artemether-lumefantrine (i.e., a median total dose of 9.6 mg/kg [interquartile range 8.7-10.7] and 57.9 mg/kg of lumefantrine [52.4-64.0]) and 50 the standard combination of artesunate (12 mg/kg over 3 d) and mefloquine (25 mg/kg). All patients had rapid initial clinical and parasitological responses. The 28 d cure rates were high: 97.7% (95% confidence interval [95% CI] 93.5-99.5%) for artemether-lumefantrine and 100% (95% CI 92.5-100%) for artesunate-mefloquine. The 6-dose regimen of artemether-lumefantrine was better tolerated than, and as effective as, artesunate-mefloquine, the current standard treatment in this area of multidrug-resistant P. falciparum malaria.

Larval habitats of anopheline mosquitoes in the Upper Orinoco, Venezuela

Survey of larval habitats of anopheline mosquitoes was conducted in Ocamo in the State of Amazonas, southern Venezuela. The sampled habitats belonged to three different hydrological types: lagoons (26 habitats), forest pools including flooded forest (16 habitats), and forest streams (4 habitats). Out of 46 habitats surveyed, 31 contained anopheline larvae. Six species were found: Anopheles darlingi, Anopheles triannulatus, Anopheles oswaldoi, Anopheles peryassui, Anopheles punctimacula, and Anopheles mediopunctatus. Anopheles triannulatus was the most abundant species. Significantly higher numbers of anopheline larvae, in general, and of An. triannulatus specifically were found in lagoons with submersed macrophytes and sparse emergent graminoids than in forest pools with detritus.

[Changes in calcium, phosphate, magnesium and sodium content in bones of ovariectomized rats]

Bilateral ovariectomies (OVX) or sham surgeries-respectively-were performed in two lots of ten female Wistar rats, 90 days old. Food was available ad libitum to sham rats, and it was restricted to OVX ones. At 15, 30, 45 and 90 days, a segment of their tails was sectioned. At 180 days all rats were sacrificed and the left femurs were excised. With the tail's bones and the femurs we determined Ca++, PO4(-3), Mg++ y Na+ concentration. After 15 days, no significant differences inter lots were observed (p < 0.05) in all ions contents. After 30 days Ca++ value was significantly less (p < 0.05) in the OVX rats than in the sham ones. After 45 days all the analyzed OVX rats ions were significantly less (p < 0.05) than the sham values. That difference inter lots was greater after 90 days. Finally, day 180th gave a decrease in the OVX rat values-from the femur-as follows: for Ca++ 31%, for PO4(-3) 29%, for Mg++ 31.6% and for Na+ 29%. Our results shown that in 90 days old ovariectomized rats, the concentration of calcium, phosphate, magnesium and sodium in the tail bones is a good indicator of bone mass loss, after 45 days of ovariectomy.

[Cicatrization effect of Jatropha curcas latex (Angiospermae: Euforbiaceae)]

The wound healing effects of Jathopha curcas latex upon surgical wound produced in Balb/c mice skin, were studied with a modification of the Hoowes-Sooy-Harvey method. The effects of topical treatment using single 50 ul doses of latex at different dilutions (10% to 100%) was compared with a multiple dose treatment (four 25 ul/dose q12h, latex 5% to 100%). The single dose treatment with 10%, 50% or 100% latex and the multiple dose treatment with dilutions between 5% and 10%, have a healing effect but only on males. The multiple dose treatment with 50% or pure undiluted latex produced caustic lesions to treated skin.

[Effects of lyophilization on four biological activities of Bothrops atrox venom (Serpentes: Viperidae)]

Fresh venom was obtained by milking both sexes of adult Bothrops atrox snakes. Four biological activities were studied in both fresh and freeze dried venom: local hemorrhagic in guinea pig skin, proteolytic upon casein (caseinolytic), esterasic upon TAME and fibrinogen clotting activity. All activities were detected in fresh venom: Hemorrhagic (DHM = 0.93, DHR = 9.75 micrograms protein), caseinolytic (0.25 U kunitz/mg protein), esterasic (0.70 U/mg protein) and clotting activity (75.7 U NIH/mg protein). After freeze drying, all the biological activity of B. atrox venom enzymes decreased: hemorrhagic, caseinolytic and clotting activity in 50% and the esterasic activity only in 15%. Our results show that lyophylization decreases several important biological activities in snake venom related to a decrease in the venom enzymatic activities.

Isoelectric focusing of cassava protoplasts

Cassava (Manihot esculenta Crantz) protoplast was analyzed by using isoelectric focusing techniques. Two populations, representing 68 and 32% of the total sample, with mean isoelectric points of 4.48 and 4.60, were obtained using mesophyll protoplasts. The use of this technique allows demonstration of a discontinuous distribution of protoplast isoelectric point from one species according to their surface potential.

Non-electrolyte diffusion across the frog gastric mucosa under osmotic gradients

Serosal-to-mucosal and mucosal-to-serosal diffusion of 14C-labelled inulin, sucrose, erythritol and propionamide was compared with 3HHO diffusion in mucosae incubated with isosmotic solutions at both surfaces, as well as isosmotic solution at serosal surface and hyperosmotic solution at the mucosal surface. The use of a hyperosmotic solution at the mucosal surface significantly increases unidirectional diffusion fluxes of inulin and of sucrose. To a nonsignificant extent, it affects the fluxes of erythritol and propionamide and significantly reduces the 3HHO diffusion. A size increment of the diffusion path utilized by the larger molecules is proposed.

Water diffusion under osmotic gradients in frog gastric mucosa

The asymmetry of the osmotic response of the frog gastric mucosa has been further analyzed by studying the effect of external tonicity changes on the water diffusion fluxes. Hyperosmotic solution at the serosal surface does not affect the water diffusion fluxes. Hyperosmotic solution at the mucosal surface, with isosmotic solution at the serosal surface, significantly reduces (P less than 0.001) the serosal-to-mucosal and the mucosal-to-serosal water diffusion. An increment in the restriction offered by the mucosa to water diffusion by effect of hypertonicity at the mucosal surface is proposed.

Asymmetry in osmotic response of frog gastric mucosa

The effects of hyperosmolality of the serosal and mucosal bathing solutions on the transmucosal net water and ion fluxes were studied in frog gastric mucosa. Addition of 100 mosM glucose to the solution at the serosal surface produces a reversed mucosal-to-serosal net water flux of 7.1 +/- 1.4 microliter . cm-2 . h-1. When added to the abolished spontaneous net water flux, this results in an increment in the net water flux of -17.8 +/- 1.4 microliter . cm-2 . h-1. Addition of the same amount of glucose to the solution at the mucosal surface produces an increment in the serosal-to-mucosal net water flux of 3.7 +/- 1.1 microliter . cm-2 . h-1 when the solution at the opposite surface was kept in 220 mosmol/kg H2O. Simultaneous increments of both solutions of 320 to 420 and 420 to 520 mosM changes the osmotic serosal-to-mucosal induced fluxes to 1.9 +/- 0.9 and 3.4 +/- 1.6 microliter . cm-2 . h-1, respectively. The initial spontaneous net water fluxes measured in 220, 320, and 420 mosM solutions were 11.3 +/- 0.9, 6.9 +/- 1.6, and -1.5 +/- 1.5 microliter . cm-2 . h-1. It is proposed that the osmotic water flux is asymmetric, independent of the solutions tonicities, and not significantly affected by the sweep of solutes at the mucosal surface.

Applied pressures and net water flux across in vitro frog gastric mucosa

The effects of hydrostatic pressure differences up to 0.4 atm/413 cmH2O were studied on frog gastric mucosa in vitro. Net water flux, transmucosal electrical potential difference, and acid secretion were measured. A significant correlation between hydrostatistic pressure difference and net water flow (r=0.77) was obtained. The intercept of the regression line, at zero hydrostatic pressure difference, is 9.3 +/- 0.5 microliter/cm2.h, and the slope 42.9 +/- 3.2 microliter/cm2.atm.h. No significant correlation was obtained between the hydrostatic pressure difference and the transmucosal potential difference (P greater than 0.20), the acid secretion (P greater than 0.20), or the nonacidic chloride transport, measured as short-circuit current (P greater than 0.20). Hydrostatic water flux is compared to osmotically induced flux previously reported. It is proposed that the difference between hydrostatic and osmotic induced water fluxes is due to the area of cells exposed to the pressures. Only part of surface cells are directly exposed to the osmotic pressure due to the presence of restricted extracellular compartments.

Weak acid accumulation in the serosal extracellular compartment of the frog gastric mucosa

The dimethyloxazolidine dione distribution in the extracellular compartments of the frog gastric mucosa was analyzed by washout kinetics. The volumes of the two extracellular compartments, serosal and mucosal, were estimated by inulin washout as 0.435 +/- 0.019 and 0.176 +/- 0.018 microliter/microliter tissue water, respectively. In the serosal extracellular space, significant dimethyloxazolidine dione accumulations of 2.63 +/- 0.25, 2.28 +/- 0.16, and 1.86 +/- 0.08 times that of the bathing media were found for bathing solutions with pH values of 6.9, 7.4, and 7.9 respectively. A high pH of the serosal extracellular fluid by itself could not account for the high values of dimethyloxazolidine dione accumulation. A difference in the total dimethyloxazolidine dione accumulation requires: (a) the existence of differences in the pH values and also the existence of a difference in the diffusion coefficient of the two forms of dimethyloxazolidine dione; or (b), a binding of one of the two forms, i.e., binding of dimethyloxazolidine dione form by fixed charges.

Response of active transport of ions and spontaneous water flux to osmotic gradients in gastric mucosa

The effects of symmetric changes of the mucosal and serosal bathing solution on cell water content, net ion flux, and net water movement were studied in the isolated frog gastric mucosa. Similar to transmucosal concentration gradients that induce water movement and changes in cell water content, symmetric osmolality changes of the bathing solutions also produce changes in these functional parameters. Thus, increments from 165 to 286 mosmol/kg water in the osmolality of both solutions reduce cell water content from 2.37 plus or minus 0.12 to 1.30 plus or minus 0.20 ml/g wt, the net ion flux (acid secretion plus short-circuit current) from 4.83 plus or minus 0.36 to 3.44 plus or minus 0.26 mueq/cm2 per h, and the net water flux from 10.6 plus or minus 1.1 to 2.4 plus or minus 1.2 mul/cm2 per h. These osmotically induced flux changes of water and ions must be considered when osmotic gradients are being used to generate and to evaluate water movement across the gastric mucosa.

Sodium, potassium, and chloride concentrations in the Schwann cell and axon of the squid nerve fiber

Sodium, potassium, and chloride concentrations were determined in the sheath cells and axoplasm of the nerve fiber of the squid Sepioteuthis sepioidea. The sheaths were obtained by slitting the nerve fiber, the extracellular electrolytes were washed out in isotonic sucrose solution, and the concentrations in the cells were determined after different soaking times in the sucrose solution. Values for the Schwann cell were calculated by extrapolation to zero time from the plots of the logarithms of the concentrations in the cells as a function of soaking time in sucrose solution. The Schwann cells made up 84 per cent of the sheath's total cellular volume. The Schwann cell concentrations in millimols per liter, are: 312 (404-241) for sodium, 220 (308-157) for potassium, and 167 (208-138) for chloride. The concentrations in the axoplasm (mean +/- SE), in millimols per liter are: 52 +/- 10 for sodium, 335 +/- 25 for potassium, and 135 +/- 14 for chloride. The possibility that some fraction of the Schwann cell electrolytes, especially of sodium, is bound, cannot be discarded.