Contribution of lethal mutations to excision assays for tumour cell survival

Conventional assays of cell survival determine only the proportion of colony-forming cells, assuming that all such cells are equivalent. However, cells surviving irradiation are reported to have lower plating efficiencies than unirradiated controls, suggesting an additional component of cellular damage that is ignored in conventional survival assays, but which could contribute to therapeutic outcome. Therefore we have examined the contribution of this additional form of damage to excision assays for cell survival in experimental tumours following both single dose and fractionated irradiation (10F/5 days) in vivo. Plating efficiencies were considerably lower for the long-term descendents of irradiated compared with non-irradiated cells. Expression of delayed reproductive death was reduced after fractionated radiation doses, only appearing after a substantial number of 3.4 Gy fractions had accumulated. Thus estimates of survival derived from single clonogenicity assays may underestimate the reduction in cell viability from a particular treatment. This could compromise assays for intrinsic radiosensitivity and mathematical modelling of the efficacy of treatment regimens.

Lobenzarit disodium inhibits the constitutive NO-cGMP metabolic pathways. Possible involvement as an immunomodulatory drug

Lobenzarit disodtulIl (CCA) is a novel immunomodulatory drug useful in the treatment of chronic inflammations. Its principal mechanism of action seems to be through enhancing the T suppressor/T helper lymphocyte ratio. However, the molecular basis for these actions remains unclear. In this study it was found that CCA inhibits the production of guanosine 3',5'-cyclic monophosphate almost completely when present in concentrations of 1 mM. Further results demonstrated that such inhibition could also be explained by interference in constitutive nitric oxide generation. In addition to previous findings, more insight into the molecular mechanism of action of CCA is provided.

Activation of phospholipase D by interleukin-8 in human neutrophils

Interleukin 8 (IL-8), a member of the C-X-C branch of the chemokine superfamily, stimulated the breakdown of 1-O-[3H]alkyl-2-acyl-sn-glycero-3-phosphocholine ([3H]EAPC) and the formation of 1-O-[3H]alkyl-2-acyl-phosphatidic acid ([3H]-EAPA) in human polymorphonuclear leukocytes (PMN) in the presence of cytochalasin B. In addition, the mass of diradyl-PA was increased with similar kinetics. In the presence of ethanol, 1-O-[3H]alkyl-2-acyl-phosphatidylethanol ([3H]EAPEt) was formed at the expense of [3H]EAPA formation, indicating the activation of phospholipase D by the cytokine. The effect was time- and concentration-dependent, reaching a plateau at 30 seconds with the maximally activating concentration of 120 nmol/L IL-8. Preincubation of cells with 1 microgram/mL Bordetella pertussis toxin inhibited the breakdown of [3H]EAPC and [3H]EAPA formation, indicating a role for a pertussis toxin-sensitive guanosine triphosphate-binding protein. Formation of phosphatidic acid (PA) correlated with activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, the oxidative burst enzyme, with both events occurring in the same concentration range. Inhibition of PA formation, by the presence of ethanol, also inhibited the oxidative burst stimulation by IL-8. Pretreatment of PMN with 10 nmol/L platelet-activating factor potentiated both [3H]EAPA accumulation and activation of NADPD oxidase by IL-8. Collectively, these data show that IL-8 stimulates the metabolism of choline-containing phosphoglycerides in human PMN and support a role for PA in the signaling mechanisms used by IL-8 to stimulate PMN function.

Activation of phospholipase D by interleukin-8 in human neutrophils

Interleukin 8 (IL-8), a member of the C-X-C branch of the chemokine superfamily, stimulated the breakdown of 1-O-[3H]alkyl-2-acyl-sn-glycero-3-phosphocholine ([3H]EAPC) and the formation of 1-O-[3H]alkyl-2-acyl-phosphatidic acid ([3H]-EAPA) in human polymorphonuclear leukocytes (PMN) in the presence of cytochalasin B. In addition, the mass of diradyl-PA was increased with similar kinetics. In the presence of ethanol, 1-O-[3H]alkyl-2-acyl-phosphatidylethanol ([3H]EAPEt) was formed at the expense of [3H]EAPA formation, indicating the activation of phospholipase D by the cytokine. The effect was time- and concentration-dependent, reaching a plateau at 30 seconds with the maximally activating concentration of 120 nmol/L IL-8. Preincubation of cells with 1 microgram/mL Bordetella pertussis toxin inhibited the breakdown of [3H]EAPC and [3H]EAPA formation, indicating a role for a pertussis toxin-sensitive guanosine triphosphate-binding protein. Formation of phosphatidic acid (PA) correlated with activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, the oxidative burst enzyme, with both events occurring in the same concentration range. Inhibition of PA formation, by the presence of ethanol, also inhibited the oxidative burst stimulation by IL-8. Pretreatment of PMN with 10 nmol/L platelet-activating factor potentiated both [3H]EAPA accumulation and activation of NADPD oxidase by IL-8. Collectively, these data show that IL-8 stimulates the metabolism of choline-containing phosphoglycerides in human PMN and support a role for PA in the signaling mechanisms used by IL-8 to stimulate PMN function.

Is there a role for ovarian stimulation and intra-uterine insemination after age 40?

The objective of this study was to determine the conception rate in infertile couples in which the female partner was > or = 40 years old and who had received ovarian stimulation treatment and intra-uterine insemination (IUI). It was a retrospective study of 77 patients who underwent a total of 210 treatment cycles. Protocols for ovulation induction included clomiphene citrate, human menopausal gonadotrophin (HMG) and clomiphene citrate plus HMG. Patients were monitored using transvaginal ultrasound, and two IUI were performed 24 and 48 h after the determination of urinary luteinizing hormone (LH) surge or human chorionic gonadotrophin (HCG) injection. A total of 11 pregnancies were reported, giving a pregnancy rate of 14% per patient and 5% per cycle. Eight spontaneous abortions occurred, giving a pregnancy wastage of 73%. In a previous comparative analysis of 543 patients < 39 years old receiving IUI and identical protocols of ovarian stimulation, 141 pregnancies were achieved, giving a pregnancy rate of 21% per patient and 10% per cycle. The miscarriage rate in that group was 18%. This report compares IUI results for women > or = 40 years with those obtained previously for younger women, and shows the very poor success rate in women > 40 years of age. This information will be important in the proper counselling of this group of patients, as well as indicating that a prompt recommendation for assisted reproductive treatment should be made soon after the failure of a few attempted cycles of ovarian stimulation treatment and IUI.

[Prefrontal dementias: clinical features and SPECT in 6 cases]

Six patients with primary degenerative dementias and frontal or frontotemporal hypoperfusion are reported. Five were diagnosed as Frontal Progressive Dementia (FPD), characterized by striking changes in personality and social behavior. The last patient had a progressive aphasia and a moderate cognitive impairment. We discuss the heterogeneity of FPD that includes Pick's disease, frontal lobe type dementia (Neary) and progressive subcortical gliosis. The usefulness of SPECT and the need of a brain bank are remarked.

Effects of glucose, ethanol, Hg(II) and Cu(II) on almond beta-glucosidase

The kinetic parameters of almond beta-glucosidase (beta-D-glucoside glucohydrolase; EC 3.2.1.21), using pNGP as substrate were kM = 2.24 +/- 0.11 mM and Vmax 588 +/- 25.1 U/mg protein. Only Hg(II) and Cu(II) showed irreversible inactivation of the enzyme. However, when these metals were present in the reaction system the inhibition effects were consistent with a mixed-type inhibition pattern (Cu(II) ki: 5.08 mM and Hg(II) ki: 0.07 mM). The glucose kinetic effect was also consistent with a mixed-type inhibition (ki = 406 mM) pattern with pNGP as varied substrate. Ethanol displayed the kinetic pattern of competitive inhibition (ki = 640 mM).

[Importance of the deficit of crystallization inhibitors in the etiopathogenesis of urolithiasis]

BACKGROUND

five percent of consultations at the Emergency Room of Catholic University Hospital are due to nephrolithiasis. The causes of this high frequency remain unknown.

AIM

to know the main metabolic and anatomic factors involved in the genesis of neprholithiasis.

PATIENTS AND METHODS

forty one patients (31 male) were studied presenting with a renal colic were studied as soon as the acute episode subsided and without diet modifications. Fasting blood calcium and creatinine and 24 h urine calcium, uric acid, citrate, magnesium and pH were measured and an intravenous pyelogram was performed. Twenty one subjects without a history of nephrolithiasis were used as controls.

RESULTS

Patients with nephrolithiasis did not differ from controls in urinary calcium (159 +/- 67 and 172 +/- 67 mg/24 h respectively), uricosuria (417 +/- 171 and 431 +/- 121 mg/24 h respectively) or urinary magnesium (55 +/- 19 and 62 +/- 21 mg/24 h respectively, whereas urinary citrate was lower (219 +/- 172 vs 319 +/- 179 mg/24 h in controls p < 0.05). All patients had normal renal functions, urinary acidification and intravenous pyelogram. Seven percent of patients with nephrolithiasis had hypercalciuria, 2.4% had hyperuricosuria. 68.3% had a low urinary citrate and 44.4% had low urinary magnesium.

CONCLUSIONS

in this sample, there is a strong association of nephrolithiasis with low levels of crystallization inhibitors in special with urinary citrate, a crystallization inhibitor.

[Epidemiology of Chagas' disease in Chile. Serological follow-up of 1,906 inhabitants from an endemic rural area, IV Region, 1991-1993]

The IV Region (29 degrees 30'-32 degrees 13' south lat.) is located in the center of the geographical area of distribution of Chagas' disease in Chile. Triatoma infestans is the main and almost exclusive vector of Trypanosoma cruzi in this country. The mean prevalence rate of T. cruzi human infection in urban and periurban sections of IV Region is 24.7%. To assess the impact of anti-T. infestans activities, by means of health education and sprayings of dwellings with insecticides, carried out in the IV Region since 1980, during January-February (summer) a serological follow-up to residents from 46 rural chagasic localities was performed. An indirect hemagglutination test and an indirect immunofluorescence test were done to each of the surveyed persons. In 1991, 303 (15.9%) out of 1,906 examined people resulted serologically positive. In 1992, previous discarding the positive individuals found in 1991, 1,334 persons were examined resulting positive 9 (0.7%). In 1993, 1,398 persons were surveyed and 26 (1.9%) were positive. It is noteworthy that none of these 35 positive persons had been surveyed in 1991, being difficult to assert if any was positive before. Two infants, daughters of positive mothers, serologically positive at the beginning, changed to negative in the following survey, indicating that it was a passive transfer of maternal specific antibodies. According to the results of this study, it is concluded that dwelling spraying with persistent-activity insecticides against T. infestans and health education are good tools in the control of T. cruzi human infection, particularly when the involved community participates.

Increases in chromosome aberrations and in abnormal sperm morphology in rubber factory workers

Subjects working at a rubber plant in a chemicals warehouse or in calandering and bambury units were analyzed for both sperm parameters and structural chromosome aberrations in peripheral blood lymphocytes. Sperm analysis was performed in a group of 24 workers for comparison with fertile (n = 24) and infertile (n = 24) control groups. The statistical analyses of semen volume, vitality and sperm count did not show significant differences between exposed and fertile groups but significant differences were found from the infertile group. A significantly lower proportion of normal sperm head shapes was found in exposed subjects when compared to the fertile group (40.1 vs. 57.8). Seven exposed workers were re-analyzed 1 year later and their sperm parameters did not change. The cytogenetic analysis showed a significant increase (3.90%) in the percentage of cells with aberrations in bambury workers (n = 11). However, no differences were found between calandering workers (n = 8) and control subjects (n = 10). Workplace air samples taken on the day of tissue sampling did not show any increase above the Cuban maximal allowed concentration for benzo[a]pyrene or toluene.

[Asymptomatic bacteriuria and pyuria during pregnancy]

BACKGROUND

The presence of pyuria and the role of mixed culture in the diagnosis of asymptomatic bacteriuria in pregnant women have been evaluated

METHODS

One hundred and sixty four pregnant women without any symptomatology have been studied using two cultures of mid-stream urine samples and pyuria quantification. In addition culture of bladder urine has been carried out in 17 of these patients (12 with pure cultures and 5 with mixed cultures).

RESULTS

110 samples were culture negative without pyuria; 7 were pure cultures with pyuria; 19 pure culture without pyuria and the remaining 28 patients yielded mixed culture with or without pyuria in the first culture. Twenty of these 28 mixed cultures were negative in the second culture. A estimated frequency of asymptomatic bacteriuria in pregnancy was 16% and pyuria was only found in 27% of pregnant women with asymptomatic bacteriuria.

CONCLUSION

The pyuria is not a useful marker for the diagnosis of asymptomatic bacteriuria in pregnancy.

Pharmacokinetics of varying doses of nicotinamide and tumour radiosensitisation with carbogen and nicotinamide: clinical considerations

Plasma concentrations, after administration of varying doses of nicotinamide, were measured in CBA male mice using a newly-developed high performance liquid chromatography assay. In all dose groups, peak levels were observed within the first 15 min after an i.p. administration of 0.1, 0.2, 0.3 or 0.5 mg g-1 of nicotinamide. There was a clear dose-dependent increase in plasma concentration with increasing dose, with almost a five-fold lower concentration (1.0 vs 4.9 mumol ml-1) achieved with a dose of 0.1 mg g-1 compared with 0.5 mg g-1, respectively. The half-life of nicotinamide increased from 1.4 h to 2.2 h over the dose range (P < 0.01). Comparisons with previous pharmacokinetic data in humans show that clinically-relevant oral doses of 6 and 9 g in humans give plasma levels slightly higher than those achieved at 1 h with doses of 0.1 to 0.2 mg g-1 in mice. Tumour radiosensitisation with carbogen alone, and with carbogen combined with varying doses of nicotinamide (0.05 to 0.5 mg g-1), was investigated using a 10-fraction in 5 days X-ray schedule. Relative to air-breathing mice, a statistically significant increase in sensitisation was observed with both a local tumour control and with an in vivo/in vitro excision assay (P < or = 0.007). With the local control assay, a trend was observed towards lower enhancement ratios (ERs) with decreasing nicotinamide dose (from 1.85 to 1.55); carbogen alone was almost as effective as when combined with 0.1 mg g-1 of nicotinamide. With the excision assay, ERs for carbogen combined with nicotinamide increased with decreased levels of cell survival. At a surviving fraction of 0.02, enhancement ratios of 1.39-1.48 were obtained for carbogen plus 0.1 to 0.3 mg g-1 of nicotinamide. These were lower than those seen with the two higher doses of 0.4 to 0.5 mg g-1 (ERs = 1.63-1.69).

Chlorpromazine inhibits both the constitutive nitric oxide synthase and the induction of nitric oxide synthase after LPS challenge

The effects of chlorpromazine on either the activity of mouse brain nitric oxide synthase or the induction of lung nitric oxide synthase in mice and rats were studied. Chlorpromazine inhibited the nitric oxide synthase activity in mouse brain cytosol. This effect could be reversed by adding an excess of calmodulin. In addition, chlorpromazine was able to inhibit the induction of lung nitric oxide synthase, in both species, after LPS administration. Furthermore, chlorpromazine also inhibited arginase activity in mouse lung cytosol.

Monocyte chemotactic protein-1 inhibits the induction of nitric oxide synthase in J774 cells

We evaluated the effect of monocyte chemotactic protein-1 (MCP-1) on the induction of nitric oxide synthase activity in J774 cells. MCP-1 was able to inhibit the production of nitric oxide induced by LPS and IFN-gamma in a dose-dependent manner. Moreover, the inhibition was only achieved when the cells were pretreated with MCP-1. No inhibition was observed when MCP-1 was added after stimulation with LPS and IFN-gamma. These results demonstrate that MCP-1 is able to inhibit the induction of nitric oxide synthesis.

[Biochemical markers of bone remodeling and bone density in healthy postmenopausal women]

The aim of this study was to study bone turnover and density in postmenopausal women. One hundred healthy postmenopausal women aged 45 to 86 years, in whom menopause occurred between 3 months and 33 years before and were not receiving medications that could alter bone metabolism, were studied. Measurements performed were serum alkaline phosphatases, urine hydroxyproline/creatinine and calcium/creatinine excretion ratios and lumbar spine and femoral bone densities. Mean urinary hydroxyproline/creatinine excretion ratio was 39.5 +/- 11.9 (over 45 in 26% of women) and calcium/creatinine ratio was 0.11 +/- 0.08 (over 0.12 in 29% of women). At least one of these measurements were increased in 39% of women and no relationship of these values with age or length of postmenopausal period was found. Alkaline phosphatases were elevated in 9.6% of women. Twenty six percent of women had lumbar spine osteopenia and 10% femoral neck osteopenia. There was an inverse relationship between the length of hypoestrogenism and bone density. It is concluded that more than one third of studied women had biochemical evidences of bone resorption and that these women had a higher frequency of osteopenia than the general population. A decrease in bone density and an increase in bone resorption indices identify women with higher risk of osteoporosis that could be benefitted with an opportune treatment.

[Vascular lesions in surgery of the lumbar spine]

We present two cases of iliac artery damage arising from surgery to correct a lumbar disc hernia due to ventral perforation. The first was a pseudoaneurysm of the left iliac artery with a retroperitoneal hematoma diagnosed by ultrasound and TAC on the third day after surgery. The second was a retroperitoneal hematoma diagnosed by intraoperative ultrasound after the patient was shifted to a new position. Emergency laparotomy was performed on both patients to repair the damage. This is an unusual but serious complication, and in most cases requires intuitive diagnosis and lifesaving surgery.

[Comparison of the frequency of electrocardiographic changes in groups of apparently healthy persons with a positive serology for Chagas' disease, for toxoplasmosis or for both parasitoses]

In order to compare the frequency of electrocardiographical abnormalities among apparently healthy persons with Trypanosoma cruzi and Toxoplasma gondii infections, electrocardiogram (EKG) and the corresponding indirect hemagglutination tests (IHAT) were performed to 13,444 randomly selected rural and suburban inhabitants from the seven first regions of Chile which are located in the geographic area of distribution of Chagas' disease in the country. The IHAT for each parasitosis resulted positive (titers > or = 1:16) for Chagas' disease alone in 1,289 (9.6%), for toxoplasmosis alone in 3,519 (26.2%) and for the two infections in 994 (7.4%). EKG abnormalities of all type (AAT) and suggestive of a chagasic etiology (ASChE) were found in 18.5 and 8.3% respectively of the T. cruzi infected group, in 10.9 and 3.2% of the T. gondii infected group, in 18.9 and 4.8% of the group simultaneously infected by the two parasites, whereas AAT and ASChE were found in 7.9 and 1.8% of the IHAT negative group. All the corresponding percentage differences between abnormal EKG had a statistical significance (p < 0.05). Besides the increasing of the IHAT positivity, for each infection parallels to the age grouping of the studied persons, a similar situation was observed in the frequence of the AAT and ASChE mainly among people aged > or = 50 years. As T. cruzi and T. gondii infections sometimes isoletely adopt a high virulence and overlap in a proportion higher than 43.0% in Chagas' disease endemic areas, it is advisable to consider these etiologic possibilities in the presence of patients with a myocardiopathy of dubious interpretation, particularly when AIDS is involved.

Renal damage in the mouse: repair kinetics at 2 and 7 Gy per fraction

The kinetics of repair of radiation damage during the intervals between fixed X-ray dose fractions of 2 or 7 Gy has been measured in the kidneys of mice. Two-gray fractions were given as one pair per day for a total of 9 days, with intervals of 0 to 12 h between the two doses in each pair. Seven-gray fractions were given as a single pair, also with different interfraction intervals. Variable top-up doses of d(4)-Be neutrons were given as two fractions separated by 1 week, starting 1 day after the last X-ray dose in each of these schedules, to increase underlying renal damage to the level at which late functional injury could be measured by reduction in renal clearance and decrease in hematocrit to 45 weeks after irradiation. Two separate experiments were carried out, and when the data from the two studies were pooled, there was no difference at all in the repair rate between the schedules using 2- or 7-Gy fractions; values of repair half-time were within 1% of one another, demonstrating no dependence on dose per fraction. In both the individual experiments and the pooled data set, repair occurred single-exponentially at both 2 and 7 Gy per fraction and there was no evidence of a "slow" component. Analyzing the whole data set together gave a repair half-time of 1.29 +/- 0.16 h (95% confidence limits) and an alpha/beta ratio of 3.22 +/- 0.16 Gy.

Role of nitric oxide pathway in the protection against lethal endotoxemia afforded by low doses of lipopolysaccharide

Survival after lipopolysaccharide challenge (LD80, 20 mg.kg-1, i.p.) was significantly enhanced by previous treatment with a microdose of LPS (50 micrograms.kg-1, i.v.). When NG-monomethyl-L-arginine, a specific inhibitor of the formation of nitric oxide from L-arginine, was given 30 minutes before microdose, survival was significantly reduced. When we monitored the serum Tumor Necrosis Factor (TNF) levels in both groups a significant reduction of TNF level after the microdose was observed in mice previously treated with L-NMMA. The ability of L-NNMA to reduce TNF release was dose dependent.

[Frequency of electrocardiographic alterations in apparently healthy persons with indirect hemagglutination reaction positive for toxoplasmosis]

An indirect hemagglutination test (IHAT) for toxoplasmosis and electrocardiogram (EKG) were performed to 11,161 apparently healthy inhabitants with negative IHAT for Chagas' disease, from 259 rural and periurban localities sited in the first seven regions of Chile (geographic area of distribution of Chagas' disease in the country). The age of the 11,161 examined people ranged between 5 and 94 years, being 4,518 males and 6,643 females. The IHAT for toxoplasmosis was considered positive with titers > or = 1:16. This test resulted positive in 3,519 (31.1%) persons (30.8% in males and 32.0% in females). Positivity of the IHAT increased from 21.2%, in the youngest group (< 10 years) up to 46.9% in the oldest group (> or = 60 years). Different types of EKG alterations were observed in 10.9% of the IHAT positive individuals and in 7.9% of the IHAT negative ones. In both groups the percentages of altered EKG increased parallel with age. The overall difference of percentages of altered EKG in IHAT positive and IHAT negative persons has a statistical significance with p < 0.001. This study suggest the convenience to consider toxoplasmosis as a cause of chronic myocardiopathy in epidemiological studies on Chagas' disease, because a possible Toxoplasma gondii infection may contribute to overincrease the magnitude of the impact of Trypanosoma cruzi in the generation of the quoted myocardiopathy.

Monoclonal antibodies to apolipoprotein AI: generation and characterization

BALB/c mice were immunized with apolipoprotein (apo AI)--high density lipoprotein (HDL) conjugate. By polyethylene glycol-induced fusion of isolated spleen cells with the myeloma cell line P3 X63 Ag8 6.5.3, three different hybridomas were obtained and characterized. Two of them were found to secrete antibodies of the IgG2a subclass, whereas the third produced antibodies of the IgG1 type. Binding capacities to 125I-apo AI and 125I-HDL were higher than 90% in all cases. The isolated antibodies recognize independent epitopes on the apo AI molecule and bind isolated HDL and serum-HDL with different affinities.

[3 beta-hydroxysteroid dehydrogenase defect: frequency of presentation in a sample of Chilean hirsute women]

The defect of 3 beta hydroxysteroid dehydrogenase (3 beta HSD) is frequent among hirsute women and clearly dependent on the ethnic composition of the studied population. Our aim was to study the frequency of 3 beta HSD deficit in a group of Chilean hirsute women. Basal and post ACTH concentrations of cortisol, 17 hydroxyprogesterone and 17 hydroxypregnenolone were measured by RIA in 40 hirsute post puberal women and in 15 normal age matched female volunteers. Criteria for considering a 3 beta HDS deficit were 17 hydroxypregnenolone values and 17 hydroxypregnenolone/17 hydroxyprogesterone and 17 hydroxypregnenolone/cortisol ratios after ACTH stimulation over the 95% confidence intervals of normal women. Basal dehydroepiandrosterone sulphate and testosterone levels were also measured in hirsute women. All samples were obtained during the follicular phase of the menstrual cycle. ACTH stimulated hormone values and ratios were diagnostic for 3 beta HDS deficit in 7.5% of hirsute women. Basal testosterone was over 80 ng/dl in 47.5% and dehydroepiandrosterone sulphate over 3.9 micrograms/ml in 52.5% of these women. There was no correlation between dehydroepiandrosterone or testosterone values and ACTH stimulated hormone values. It is concluded that 3 beta HSD is frequent in hirsute women and that its diagnosis requires the determination of ACTH stimulated 17 hydroxypregnenolone values and 17 hydroxypregnenolone/17 hydroxyprogesterone ratio.

Generation of murine triomas secreting bi-specific monoclonal antibodies that recognize HBsAG ad and ay subtypes

We report the generation of murine triomas by fusing splenocytes from mice previously immunized with HBsAg ay-subtype and a hybridoma, secreting anti-HBsAg ad-subtype monoclonal antibody, which was rendered HGPRT- by induced mutagenesis with N-methyl-N'nitro-N-nitrosoguanidine. The fusion yielded a 83.8% of hybrids showing the antigen specificity of the parental hybridoma and a 16.1% of bi-specific monoclonal antibodies. One of them, coded as 1C8A5, showing a heavy chain isotype (IgG1/IgG2b) was used as capture reagent in an ultramicro-ELISA. As little as 0.78 I.U. of both HBsAg ad- and ay-subtypes could be realiably detected.

Pharmacokinetics of nicotinamide and its effect on blood pressure, pulse and body temperature in normal human volunteers

The pharmacokinetics of nicotinamide were studied in four human volunteers after oral doses of 1-6 g. Plasma concentrations and clearance rates of the vitamin were found to be dose-dependent, with a half-life of approximately 7-9 h for the two highest doses administered (4 and 6 g), approximately 4 h with 2 g and approximately 1.5 h with a 1-g dose. Peak concentrations ranged from 0.7 to 1.1 mumol.ml-1 after a 6-g dose. The time to reach peak plasma concentration was dose independent with a broad range from 0.73 to 3 h. In this study, nicotinamide had no detectable effect on blood pressure, pulse or body temperature.

[Current prevalence of trichinosis in Santiago, Chile (1992). A study on 500 corpses]

In August-December 1992, 500 diaphragm muscle samples taken at random from people who were autopsied at the Santiago Medico-Legal Service, were submitted to phototrichinoscopy to search for encysted larvae of Trichinella spiralis. For each sample seven small pieces were examined. Three hundred and eighty nine (77.8%) cadavers corresponded to males and one hundred and eleven (22.2%) to females. Ages ranged from 1 to 90 years. Ten (2.0%) of the individuals examined resulted positive, the higher frequencies corresponding to individuals over 20 years of age. The prevalence rate of T. spiralis infection found is rather similar to those detected in 1966-1967, 1972 and 1982, with percentages of 2.2, 3.4 and 2.8 respectively.

[Electrocardiographic alterations in persons with a positive serology for toxoplasmosis]

To each of 11,161 randomly taken people from urban and peri-urban localities of the first seven regions of Chile (geographic area of distribution of Chagas' disease in the country), with negative serology for Chagas' disease, an indirect hemagglutination test (IHAT) for toxoplasmosis and an EKG were practiced. The IHAT for toxoplasmosis resulted positive in 3,519 individuals (31.5%). The EKG showed alterations in 10.9% of the IHAT positive individuals and in 7.9% of the IHAT negative ones. This difference between the proportion of altered EKG in IHAT positive people and altered EKG in those with negative IHAT is statistically significative with p < 0.001. These results suggest the convenience of considering toxoplasmosis as a cause of chronic myocardiopathy in epidemiological studies on Chagas' disease, since not discard the presence of Toxoplasma gondii infection should overvaluete the magnitude of the impact of Trypanosoma cruzi in the genesis of such a myocardiopathy.

No increase in chromosome aberrations in workers from an oil catalytic cracking plant

A study of structural chromosome aberration frequencies in blood lymphocytes was performed in a group of 20 oil catalytic cracking unit workers and in 26 subjects belonging to the office staff of an oil refining plant, as well as in 35 matched controls. Subjects in the latter group were of the same sex (males) and similar age as the exposed group, and had similar smoking habits. Benzo[a]pyrene levels in workplace air samples were also determined. The cytogenetic analysis failed to show any differences between the exposed and control groups. A slight increase in benzo[a]pyrene level above the Cuban national standard of 1 ng/m3 was found during the air sample analysis in the oil catalytic cracking unit.

A test of equal effect per fraction in the kidney of the mouse

Measurements of renal damage in the mouse were made to determine if there was an equal effect per fraction during a course of repeated 240-kVp X-ray doses. An X-ray dose of 2 Gy was given 2, 8, 14, or 20 times with interfraction intervals of 12 h. Some animals were also irradiated with twenty 2-Gy doses using a 5-h interfraction interval. The underlying effect per fraction (-logeSF of the notional target cell population) was determined from the additional top-up dose of d(4)-Be neutrons needed to produce measurable renal impairment assessed by decreased clearance from the plasma of [51Cr]EDTA and by a reduction in the hematocrit at 25, 29, 33, and 39 weeks after treatment. There was no significant influence of the time of assay on the values of underlying effect measured. A mean value of underlying effect was therefore calculated for the two different assays of each mouse, from the measurements at the four times. This gave approximately 40 estimates (one for each animal assessed) with each assay of the effectiveness of 2-Gy fractions in each of the four fractionation schedules, a total of 321 determinations in the study with 12-h intervals. Regression analysis showed that there was no significant trend in underlying effect per fraction with number of fractions, i.e., the damage per fraction was constant regardless of the number of fractions used. With underlying effect normalized to 1 unit of damage for a single 2-Gy dose, the slope of this plot was -0.0013 per fraction2 +/- 0.0097 (95% CL). The assumption of equal effect per fraction was therefore not invalidated in the kidney of the mouse. With a 5- instead of a 12-h interfraction interval, the 20-fraction schedule was 7% more effective as measured by the two assays analyzed together; this was significant at P = 0.0001. This shows that 5 h is not sufficient time between fractions for full repair to occur in the kidney, and underlines the need for intervals of at least 6 h between the doses in clinical radiotherapy using more than one fraction per day. The data are consistent with an alpha/beta ratio approximately 1.6 Gy, with a repair half-time approximately 1.3 h. However, these experiments were not designed to determine these parameters and their values should be regarded only as rough estimates.

Evaluation of three rapid enzyme immunoassays and cell culture for detection of respiratory syncytial virus

Three rapid enzyme immunoassay techniques for the detection of respiratory syncytial virus antigen (Becton Dickinson Directigen RSV, Abbott RSV Testpack and Abbott RSV EIA) and cell culture were evaluated in a total of 250 nasal washings. The sensitivity and specificity were 62% and 76% respectively for Directigen, 64% and 86% for RSV Testpack, and 76% and 81% for RSV EIA, taking cell culture as the reference method. Agreement between cell culture and EIA techniques was 79% (70 positive and 128 negative results). All three EIA techniques gave positive results in 69 samples (52 positive and 17 negative in the cell culture). In 121 samples all three EIA techniques gave negative results (103 negative and 18 positive in the cell culture). Using the cell culture technique 46 strains other than respiratory syncytial virus were isolated.

No increase in chromosome aberrations in lymphocytes from workers exposed to nitrogen fertilisers

The putative genetic risk of people occupationally exposed to nitrogen fertilisers was studied using the structural chromosome aberration assay in peripheral blood lymphocytes. The exposed group included 23 subjects working at complex and mixed fertiliser plants. The percent of aberrant cells (Ab.C %) and break to cell ratio (B/C) were 0.95% and 0.01 respectively. The matched control group (20 subjects) was found to have 0.80% Ab.C and a B/C ratio of 0.0085. The results show a lack of detectable genetic damage in exposed people using this cytogenetic approach.

Enhancement of tumor radiosensitivity and reduced hypoxia-dependent binding of a 2-nitroimidazole with normobaric oxygen and carbogen: a therapeutic comparison with skin and kidneys

To evaluate the therapeutic potential of normobaric oxygen and carbogen as hypoxic-cell sensitizers, both radiosensitization in a mouse mammary carcinoma, mouse skin and kidneys, and the reduction in the proportion of hypoxic tumor cells were quantified in mice breathing air, oxygen, or carbogen. Local tumor control, acute skin reactions, reduced renal clearance, and hematocrit were used as assays. X rays as 10 fractions in 5 days were given to skin and tumors and 10F/12 days to kidneys. In the tumor study, the pre-irradiation breathing time was varied from 2 to 20 min. Hypoxic cells, before and during a 10F/5 day schedule, were quantified using a 2-nitroimidazole with a theophylline side chain. Bioreductively reduced metabolites of this probe were localized in hypoxic cells that were then stained using an immunofluorescent technique and analyzed by flow cytometry. The fraction of cells with high fluorescence intensity was 19% in air, 9% in oxygen, and 3% in carbogen-breathing mice. For all three gases, hypoxia-dependent binding was similar in non-irradiated tumors and those treated with four or nine fractions. Both gases significantly enhanced tumor radiosensitivity (ER = 1.3 to 1.6) and carbogen was slightly more effective than oxygen. With carbogen, maximum sensitization was observed with a 5 min pre-irradiation breathing interval. With oxygen, pre-irradiation breathing times of 2-20 min gave similar sensitization. In skin an enhancement ratio of 1.2 was observed, whereas enhancement ratios for both renal endpoints were significantly lower (1.0 to 1.07). Relative to both tissues, there was therefore a substantial therapeutic gain by irradiating CaNT tumors under both gases, especially with carbogen.

[Chagasic infection in blood donors from hospitals in endemic regions of Chile (1982-1987). Epidemiological impact of the problem]

Chagas' disease, produced by Trypanosoma cruzi and transmitted by hematophagous triatomine bugs, exists in the Western Hemisphere from the south-western United States to central Chile and Argentina. It exists in rural and periurban sections of the northern half of Chile, with a prevalence of 16.9%. Constant rural-urban migrations have contributed to its spreading to urban sections. In order to investigate the impact of these migrations on the population susceptible of being blood donors and the probable increasing of the risk of T. cruzi transmission by blood transfusion, epidemiological surveys were carried out in donors from 22 hospitals located in the northern half of Chile. By means of an indirect hemagglutination test for Chagas' disease 16,841 blood donors were examined, arising a 2.7% of positivity, percentage that permitted to estimate that 126,477 potential blood donors infected with T. cruzi should be in the urban sections studied. These facts strengthen the need that serology for Chagas' disease must be routinely performed in endemic regions of the country, to adopt or reinforce the pertinent preventive measures.

[Evaluation of 2 techniques for ventilation support during single-lung ventilation]

In a group of 22 patients undergoing thoracotomy we compared two techniques of ventilatory assistance to the nondependent lung during single lung ventilation. We simultaneously administered a 0.5% FiO2 to the dependent lung. We used a CPAP system with continuous O2 flow limited by an underwater valve at a pressure of +5 cmH2O. We performed 33 ventilatory assistances: in 15 cases to the nondependent lung (CPAP group) and in 18 patients to the lower lobe of the nondependent lung (lobar CPAP group). Evaluation of both techniques was performed by means of arterial blood gas measurement and the mean values were compared using the student's t test. During single lung ventilation the PaO2 in CPAP group increased from 85.86 +/- 22.28 mmHg to 155.52 +/- 59.54 mmHg (p less than 0.001) and in the lobar CPAP series it increased from 88.75 +/- 24.34 mmHg to 122.36 +/- 43.21 mmHg (p less than 0.01). In 11 out of the 22 patients we firstly applied the lobar CPAP and thereafter the CPAP to the whole lung in order to compare the efficacy of both techniques in the same patient. The PaO2 during single lung ventilation was 86.9 +/- 22.7 mmHg and it increased to 111.1 +/- 37.9 mmHg after lobar CPAP (p less than 0.01) ant to 163.3 +/- 64 mmHg after total lung CPAP ventilation (p less than 0.001). Our results confirm the usefulness of both techniques and they indicate that CPAP to the whole nondependent lung is the most effective.

[Laboratory study on the immediate and persistent insecticide activity of the pyrethroid lambda-cyhalothrin on nymphs of IV instar Triatoma infestans]

Lambda-cyhalothrin (LCT) is a new broad-spectrum synthetic pyrethroid insecticide with efficient immediate and persistent activity against a great variety of arthropods harmful both to human and animal health and to vegetal production. In many countries this insecticide has been successfully used in the control of infectious diseases vectors, such as mosquitoes, triatomine bugs (transmitters of Trypanosoma cruzi, agent of Chagas' disease) and other arthropods. In order to test the immediate and persistent activity of LCT under laboratory conditions (27 degrees C and 75-80% humidity) on laboratory reared Triatoma infestans--the most resistant instar of this insect to the commonest insecticides used--a series of six experiments was performed in 1-year period. Previous to experiments, the interior surface (400 cm2) of 36 specially manufactured cardboard boxes was uniformly sprayed with 2 ml of the following substrates: 12 with 0.6% LCT suspension, 12 with 1.0% LCT suspension and 12 with water (controls). Twenty four hours, 30 - 90 - 150 - 270 and 360 days later, in two pairs of each six boxes, lots of 10 T. infestans IV nymphs were deposited inside of them. In each of the six experiments, daily observations of the conditions of the insects (unaffected, affected in terms of various grades of progressive uncoordination, or dead) after exposure to the insecticide were performed to end with the register of these conditions 96 hours later. Moreover, after 7 and 10 days of exposure in the immediate and persistent effect of LCT respectively a 100% of mortality was verified.(ABSTRACT TRUNCATED AT 250 WORDS)

Screening for antimicrobial activity of crude drug extracts and pure natural products from Mexican medicinal plants

Preliminary antimicrobial screening against Candida albicans and selected Gram-positive and Gram-negative bacteria of methanol extracts prepared from eight Mexican medicinal plants, noted for their antiseptic properties, was conducted. The significant activity exhibited for extracts of Ratibida latipalearis, Teloxys graveolens, Dodonaea viscosa, Hyptis albida, H. pectinata, H. Suaveolens and H. verticillata tends to support their traditional use as anti-infective agents. Only the extract of Hintonia latiflora was inactive. The antimicrobial activities of 44 pure natural compounds and two derivatives were determined. Of these, only 23 compounds were effective in inhibiting the growth of the tested organisms (MIC less than or equal to 100 micrograms/ml).

[Evaluation of IgG and IgA type antibodies to capsid and early antigens of the Epstein-Barr virus in the diagnosis of nasopharyngeal carcinoma]

BACKGROUND

The Epstein-Barr virus (EBV) is related with nasopharyngeal carcinoma (NPC) in that, in this neoplasm, high levels of antibodies are found vs different EBV antigens.

METHODS

The determinations of IgG and IgA type antibodies were evaluated vs capsid antigens (VCA) and early antigen (EA) of the EBV by indirect immunofluorescence in 14 patients diagnosed with NPC, in 12 patients with other tumors of the head and neck and in 61 blood donors.

RESULTS

The detection of IgA type antibodies with a sensitivity and specificity of 100% and 92% for the VCA antigen and of 86% and 100% for the EA antigen are the most useful tests in the early diagnosis of nasopharyngeal carcinoma. The determination of IgG type antibodies were of a more limited usefulness with sensitivities and specificities of 86% and 67% for IgG anti-VCA and 100% and 83% of IgG anti-EA.

CONCLUSIONS

The detection of antibodies vs VCA and EA antigens is useful in the differential diagnosis of NPC with other tumors of the head and neck.

[Evaluation of 2 serological techniques in the diagnosis of neurocysticercosis: complement fixation reaction and Western blot]

Evaluation of two serological techniques for diagnosis cysticercosis: complement fixation reaction and Western blot. Comparative study that includes 49 sera samples and 30 CSF samples belonging to 35 patients with clinical diagnosis of cysticercosis of the CNS. As a control group we used 10 sera samples of patients with Trichinella spiralis infection, 33 sera samples of patients with hydatid cyst disease, 9 sera samples from patients with oxyuriasis, 52 sera samples of healthy blood donors and 22 additional CSF samples from patients with different CNS disorders. Thirty-one samples were positive by Western blot technique and 21 samples by complement fixation reaction technique. Agreement between both techniques was 76%. Gathering clinical and laboratory information we believe that a total of 11 patients had cysticercosis of the CNS (33 samples), and three additional patients remain with indeterminate diagnosis. We have also detected cross-reactions with Western blot techniques (reactivity to more than one band) in 43% of patients with hydatid disease and in 20% of patients with Trichinella spiralis infection, but none in oxyuriasis patients. The CFR technique had cross-reaction with 33% of sera samples from hydatid disease patients and 20% of those from oxyuriasis patients. No cross-reactions were seen in any of control patients with both techniques. The two different techniques tested can be of help, together with clinical and radiology data, in the diagnosis of cysticercosis of the CNS. However, both techniques showed strong cross-reactions with hydatid disease.

A therapeutic benefit from combining normobaric carbogen or oxygen with nicotinamide in fractionated X-ray treatments

The ability of normobaric oxygen and carbogen (95% O2 + 5% CO2) combined with nicotinamide to enhance the radiosensitivity of two rodent adenocarcinomas and of mouse skin and kidneys, using a 10 fraction radiation schedule, was compared with the effect of radiation in air with and without the drug. Tumour response was assayed using local control and regrowth delay, and compared with acute skin reactions, decreased renal 51Cr-EDTA clearance and reduction in haematocrit. Nicotinamide increased the radiation sensitivity of CaNT tumours under all three different oxygen concentrations tested (21, 95 and 100% oxygen). The effect was statistically significant for oxygen and carbogen but not for air; the combination of nicotinamide with carbogen gave the greatest increase in tumour radiosensitivity. Relative to treatments in air without the drug, the enhancement ratios (ER) at the TCD50 level were 1.17, 1.65 and 1.83 for CaNT tumours irradiated in air, oxygen or carbogen and injected with nicotinamide 1 h before each fraction. The ER in CaRH tumours irradiated in carbogen plus the drug was 1.83, which was greater, but statistically not significantly different, to that seen with carbogen alone (ER = 1.68). In skin, relative to air without the drug, the increase in radiosensitivity by nicotinamide was greater in oxygen and carbogen than in air (1.29, 1.36 and 1.08, respectively). The ERs for both assays of renal damage were similar and lower than those in skin: less than or equal to 1.07, less than or equal to 1.13 and less than or equal to 1.16 for irradiations done in air, oxygen and carbogen plus nicotinamide, relative to air alone. A comparison of these results in the tumours and normal tissues showed that a significant therapeutic benefit was obtained with normobaric oxygen and carbogen combined with nicotinamide. This benefit is greater than observed with other radiosensitizers tested so far. Toxic side effects of the treatment are unlikely in a clinical situation, since prolonged administration of nicotinamide is well tolerated in man. The combination of normobaric carbogen with nicotinamide could be an effective method of enhancing tumour radiosensitivity in clinical radiotherapy where hypoxia limits the outcome of treatment.

Response of the mouse mediastinum to single and fractionated X-rays

The acute oesophageal response, after localized mediastinal irradiation in unanaesthetized mice, was assessed with a sequential, non-invasive and clinically orientated assay. Changes in body weight, after single and fractionated X-ray doses (8 fractions in 8 or 15 days and 4 fractions in 4 or 13 days), were recorded and the nadir of weight loss for each regime was used as the end-point. In our studies, quantal and non-quantal analyses of the weight loss data gave good dose-response relationships. The shapes of the dose-effect curves for single doses, 4F/4 days and 8F/8 days showed a remarkable degree of radioresistance, which became less apparent when the overall time was increased to 13 and 15 days for 4 and 8 fractions, respectively. The alpha/beta values (7-17 Gy) are within the range found for other acutely responding normal tissues. Histopathological changes were also assessed and the structural changes observed in the oesophageal epithelium, after a single dose of 34 Gy or after 46 Gy given as 3F/6 days, correlated with the gross changes observed in body weight.

[Household chagasic endemia detected as a consequence of a case of congenital infection]

During a study on prevalence of parasitic and viral serological markers in pregnant adolescents, a 17-year-old primipara from Polpaico, village near Santiago, gave birth to a normal male newborn in a Santiago hospital. As both of them presented positive an indirect hemagglutination test (IHAT) for Chagas' disease and the corresponding xenodiagnosis (XD), the infection in the infant was considered to be acquired through the placental route. According to recent epidemiological surveys Polpaico is an endemo-enzootic chagasic rural settlement, where 14.7% of dwellings were infested with Triatoma infestans, while triatominae, persons and domestic mammals were found infected with Trypanosoma cruzi. One month later the adolescent mother, her son and other 11 consanguineous members of the family were visited in their homes in order to submit each of them to a physical examination and to IHAT for Chagas' disease, and XD to those whose IHAT resulted positive. Thus, in 7 (53.8%) the IHAT was positive and in 4 (57.1%) out of these 7 presented positive the XD, results that as a whole yielded a household chagasic endemics.