Prevalence of multiple sclerosis in Buenos Aires, Argentina using the capture-recapture method

BACKGROUND

Scarce data exist about multiple sclerosis (MS) prevalence in South America. The objective of the study is to determine the prevalence of MS in a high populated area from Argentina (Greater Buenos Aires Metropolitan area) using the capture-recapture methodology.

METHODS

Greater Buenos Aires is the generic denomination that refers to the megalopolis comprised by the autonomous city of Buenos Aires and the surrounding conurbation of the province of Buenos Aires. The study was carried out taking July 1996 as the prevalence month. We used capture-recapture method to estimate the prevalence of MS cross matching registries from four MS Centers.

RESULTS

A total of 803 registries were obtained from the four lists. Log-linear model for capture-recapture method was used to analyze the data. The population of the area based on the 1990 census was 12,594,974; the number of MS cases estimated amongst sources interactions were between 1833 and 2359; the prevalence estimated ranged from 14 to 19.8 cases per 100,000 inhabitants.

CONCLUSIONS

This is the first study to provide epidemiological data on the prevalence of MS in a large population in Argentina (Greater Buenos Aires Metropolitan area). Further epidemiological studies will clarify the true prevalence of MS in South America.

Hospital injury rates in relation to socioeconomic status and working conditions

OBJECTIVES

To describe the risk of work injury by socioeconomic status (SES) in hospital workers, and to assess whether SES gradient in injury risk is explained by differences in psychosocial, ergonomic or organisational factors at work.

METHODS

Workforce rosters and Occupational Safety and Health Administration injury logs for a 5-year period were obtained from two hospitals in Massachusetts. Job titles were classified into five SES strata on the basis of educational requirements and responsibilities: administrators, professionals, semiprofessionals, skilled and semiskilled workers. 13 selected psychosocial, ergonomic and organisational exposures were assigned to the hospital jobs through the national O*NET database. Rates of injury were analysed as frequency records using the Poisson regression, with job title as the unit of analysis. The risk of injury was modelled using SES alone, each exposure variable alone and then each exposure variable in combination with SES.

RESULTS

An overall annual injury rate of 7.2 per 100 full-time workers was estimated for the two hospitals combined. All SES strata except professionals showed a significant excess risk of injury compared with the highest SES category (administrators); the risk was highest among semiskilled workers (RR 5.3, p<0.001), followed by nurses (RR 3.7, p<0.001), semiprofessionals (RR 2.9, p = 0.006) and skilled workers (RR 2.6, p = 0.01). The risk of injury was significantly associated with each exposure considered except pause frequency. When workplace exposures were introduced in the regression model together with SES, four remained significant predictors of the risk of injury (decision latitude, supervisor support, force exertion and temperature extremes), whereas the RR related to SES was strongly reduced in all strata, except professionals.

CONCLUSIONS

A strong gradient in the risk of injury by SES was reported in a sample population of hospital workers, which was greatly attenuated by adjusting for psychosocial and ergonomic workplace exposures, indicating that a large proportion of that gradient can be explained by differences in working conditions.

Pharmacokinetics of deflazacort in renal transplanted and hemodialyzed children

Deflazacort (DFZ) pharmacokinetics was evaluated in fifteen pediatric patients on chronic hemodialysis or after renal transplantation, and in three normal children. After overnight fasting, oral DFZ 0.26+/-0.01 mg/kg (mean +/- SEM) was given. Serial blood samples were collected for 360 min and analyzed by HPLC for 21-hydroxy-DFZ (21-HO-DFZ). Serum concentration profiles and pharmacokinetic parameters were similar in patients on hemodialysis, renal transplant recipients and normal children. Elimination half-life was longer in the 9 cyclosporine-treated subjects (108.0+/-13.6 min) than in the other nine (71.2+/-8.3 min; p <0.02). Our finding suggests that, from a pharmacokinetic point of view, DFZ dose adjustment for renal function is not necessary in children with chronic renal failure or after renal transplantation.

Effect of dexamethasone on osseointegration: a preliminary experimental study

The peri-implant reparative process is one of the factors involved in osseointegration. Local and systemic factors may contribute to the peri-implant micro-environment. The aim of this study was to assess the effect of dexamethasone (DXM) on the first stages of the post-implantation reparative process using a quantitative osseointegration experimental model previously developed at our laboratory. A titanium laminar implant was inserted into the right tibiae of nine male Wistar rats under ether anesthesia, following a technique we previously described. Six rats received 120 micrograms/kg/day i.p. doses of DXM (Decadron Sidus, Argentina) for 14 days pre-implantation and 14 days post-implantation. The remaining three (controls) were injected with an equivalent volume of saline. On day 14 post-implantation, all animals were killed, and their tibiae were resected, radiographed, and processed before being embedded in methylmethacrylate. Microscopic observation and histomorphometric studies were performed. Results show that, in this experimental model, the extension of osteogenic peri-implant response was greater in DXM-treated animals than in controls. Thus, our laminar implant test may prove useful to study the effects of corticosteroids on the osseointegration process.

Diastolic pressure underestimates age-related hemodynamic impairment

It has been hypothesized that as large arteries become more rigid with age, the pattern of hypertension changes from diastolic to systolic. Thus, diastolic blood pressure (DBP) may lose its ability to reflect the increase in vascular resistance with age. To assess this, we studied the age-related changes in blood pressure pattern and its steady-state and pulsatile determinants. We performed an epidemiological analysis based on a national survey of 10,462 subjects from Argentina. A hemodynamic analysis (impedance cardiography) was then carried out in 636 consecutive hypertensive patients (age, 25 to 74 years). Whereas the rate of increment in the prevalence of mild to moderate hypertension (MMH) reached a plateau after the sixth decade, isolated and borderline systolic forms of hypertension began a steep and sustained rise. Among patients with MMH, DBP remained stable from the third to the seventh decade, whereas SBP maintained a sustained increase. Despite similar DBP, the systemic vascular resistance index increased 47% (P<.01) and the cardiac index decreased 27% (P<.01), whereas the ratio of stroke volume to pulse pressure, an index of arterial compliance, decreased 45% (P<.01). However, there were no significant differences between older patients with MMH and those with isolated systolic hypertension in the level of SBP, vascular resistance, stroke volume, and cardiac index. Compared with age-matched normotensive control subjects, the ratio of stroke volume to pulse pressure was much more reduced in isolated systolic hypertension (48%) than in MMH (30%). In summary, the present study, carried out in a large sample of hypertensive subjects with a wide age range, showed a simultaneous impairment in vascular resistance and arterial compliance associated with aging in different patterns of hypertension. The magnitude of these changes, with opposite effects on DBP but additive effects on SBP, suggests that a hemodynamic mechanism could determine the transition in the prevalence of diastolic hypertension toward a systolic pattern of hypertension with aging. Also, the results suggest that SBP, but not DBP, is a reliable indicator of the underlying hemodynamic abnormalities (high resistance and low arterial compliance) in the elderly.

Inhibitory effects of diazepam in rat vas deferens: role of calcium

Diazepam and Ro5-4864 effects on noradrenaline-induced rat vas deferens contractions were studied. We investigated whether central or peripheral type benzodiazepine receptors were involved, by studying the effects of the selective central or peripheral benzodiazepine receptor antagonists, flumazenil (Ro 151788) or PK 11195 respectively. Diazepam interactions with GABA, adenosine, theophylline, and hypercalcic medium (3.5 mM) were studied. Also, we investigate diazepam effect on KCl depolarized vas deferens. Results showed that diazepam (10(-4) to 1.7 x 10 (-4) M) and Ro 5-4864 (10(-5) to 5.5 x 10(-5) M) inhibited NA-induced vas deferens contractions and that neither flumazenil nor PK 11195 antagonized diazepam or Ro 5-4864 inhibitory effects respectively. GABA, adenosine and theophylline did not modify neither NA vas deferens response nor diazepam inhibitory action. Diazepam effect was significantly reduced in and 3.5 mM calcium medium and KCl vas deferens response was inhibited by diazepam 1.3 x 10(-5) and 1.3 x 10(-4) M. It is concluded that in rat vas deferens diazepam effect seems to be related with calcium mobilization.

Vasodilatory effects of propylthiouracil in patients with alcoholic cirrhosis

BACKGROUND/AIMS

An experimental study has shown that propylthiouracil increases portal blood flow in normal rats. Whether propylthiouracil has a similar effect in patients with alcoholic cirrhosis remains to be demonstrated. The aim of this study was to evaluate the effects of oral propylthiouracil (300 mg) on systemic and portal hemodynamics in patients with alcoholic cirrhosis.

METHODS

Plasma propylthiouracil levels were also measured by high performance liquid chromatography in five patients with alcoholic cirrhosis. In eight patients with cirrhosis, mean arterial pressure, cardiac output and portal blood flow were evaluated before and after placebo and propylthiouracil administration. Hemodynamic measurements were performed by the Doppler technique. The plasma peak level of propylthiouracil was achieved at 1.4 +/- 0.1 h in patients with alcoholic cirrhosis. This time was chosen to express hemodynamic changes.

RESULTS

Propylthiouracil administration caused a significant increase in portal blood flow (+16.5%, p < 0.05) in patients with alcoholic cirrhosis. This effect was associated with a mild and significant rise in cardiac output (from 5.8 +/- 0.2 to 6.1 +/- 0.3 l/min, p < 0.05) and a decrease in peripheral vascular resistance (from 1171 +/- 69 to 1070 +/- 67 dyn . s-1 . cm-5, p < 0.01). A significant correlation was observed between changes in portal blood flow and peripheral vascular resistance (r = 0.79, p < 0.05). No significant changes were observed after placebo.

CONCLUSIONS

Our findings show that propylthiouracil has a vasodilatory effect in patients with alcoholic cirrhosis. We postulate that this effect could be the mechanism by which propylthiouracil decreases hypermetabolic state, and increases oxygen delivery to the liver, in patients with alcoholic liver diseases.

Steady-state hydroxyflutamide plasma levels after the administration of two dosage forms of flutamide

A bioavailability study of randomized cross-over design was carried out in eight volunteers who were given a 48-h flutamide treatment consisting of 250-mg tablets three times daily or 400-mg sustained-release tablets twice daily, followed 3 weeks later by the alternative dosage form. Just before the last dose and 15 times during the subsequent 24 h, blood samples were obtained for the determination of plasma hydroxyflutamide (the active metabolite of flutamide) levels by high-performance liquid chromatography. No statistically significant differences between the two dosage forms were found for the lag time, rate of initial increase in concentration, peak plasma concentration, mean hydroxyflutamide concentration within one dosing interval or 24-h AUC value. One subject presented mild and transient nausea during both treatment periods. After the first treatment period (250-mg tablets), an increase in serum bilirubin was observed in another volunteer, who was withdrawn from the study. It may be concluded that both dosage forms were bioequivalent.

Effects of enalapril on renal parameters in patients with primary glomerulopathies associated with chronic renal failure

14 patients (8 male, 6 female), aged 35 to 64 years, with glomerulopathies consisting of membranoproliferative glomerulonephritis (GN) [n = 6], membranous GN (n = 3), focal and diffuse glomerulosclerosis (n = 4), and post-streptococcal GN (n = 1) were studied. Diagnosis was established by renal biopsy in 12 of the 14 patients. All 14 patients had impaired renal function (creatinine clearance = 25 to 55 ml/min) and proteinuria (1.0 to 10.4 g/day). Five normotensive patients received enalapril 20 mg/day, whereas 9 patients with hypertension received 20 to 40 mg/day to control blood pressure. Diuretics were administered concomitantly to 8 patients. Patients attended the clinic every 14 days for 30 months and their diets were closely monitored, with sodium intake limited to between 50 and 100 mEq/day and protein to between 1.0 and 1.2 g/kg/day. Blood pressure was significantly controlled in the patients with hypertension. Serum creatinine, blood urea nitrogen, creatinine clearance and 24-hour urinary protein excretion all significantly improved during the 30-month study. No adverse clinical events were noted. Thus, over a period of time, enalapril therapy may improve the prognosis of patients with glomerulonephritis by maintaining glomerular filtration rates and decreasing proteinuria and blood pressure.

Two fatal cases of type E adult food-borne botulism with early symptoms and terminal neurologic signs

Type E botulism, one of the least common forms of botulinal intoxication on the East Coast of the United States, is described for two elderly patients with chronic underlying disease. Both patients consumed tainted kapchunka, a salted, ungutted whitefish. Gastrointestinal symptoms and signs were prominent, but neurologic complaints, although noted soon after the consumption of the fish in one patient, did not progress until late in the course of the patient's illness. One patient exhibited both urinary retention, which was reported mainly in one outbreak of type E botulism (M.G. Koenig, A. Spickard, M.A. Cardella, and D.E. Rogers, Medicine [Baltimore] 43:517-545, 1964), and muscular fasciculations, which have been rarely reported.

Potential subtypes of Chlamydia psittaci based on effects of cortisone with cytochalasin B or cycloheximide

Strains of Chlamydia psittaci were differentiated as to their biological characteristics using growth in Vero cells. These host cells were chlamydial infected without centrifugation, but treated with either cortisone and cytochalasin B or cortisone and cycloheximide. The criterion was the time of 100% cytopathic effect and specific sloughing, accompanied by the maximum infectivity of C. psittaci. Possible subtypic characteristics were determined for three avian strains.

Comparative titers of egg assay against immunofluorescent assay of Chlamydia psittaci

A comparison of titers was made between an egg assay and a direct fluorescent antibody assay of three chlamydial strains propagated in Vero cells with and without cortisone plus cytochalasin B. The titer of NJ-1 strain was similar in the egg titration and the fluorescent antibody assay in the untreated sample and a little lower for the sample treated with cytochalasin B and cortisone. The SCT and CDC strains had approximately the same titers in the egg titration and the fluorescent antibody assay for samples with and without the antimetabolites.

Growth of several strains of Chlamydia psittaci in Vero and McCoy cells in the presence of cytochalasin and cortisone

Chlamydia psittaci of avian and mammalian origin were grown in McCoy and Vero cells in the presence of cytochalasin B with cortisone acetate. Six turkey strains, one parrot strain, one human strain, one ovine strain and one bovine strain were used in this study. All strains, except the turkey strain NJ-1, grew to higher titers in Vero cells than in McCoy cells. Five of the six turkey strains could be grouped together because they induced cytopathic changes rapidly. The other turkey strain, along with the parrot, human and ovine strain, induced cytopathic changes more slowly and the bovine strain failed to cause cytopathic changes, but it did replicate in the cell culture system.

Goat serums for fluorescent antibody conjugates to chlamydial antigens

Serums from goats hyperimmunized with Chlamydia psittaci consistently produce antichlamydial fluorescent antibody conjugate of high titer. The titer of the fluorescent antibody conjugate prepared from a given serum correlated well with the titer obtained by agar gel precipitin, but not with the complement fixation. The agar gel precipitin test can be used to predict whether a given serum is satisfactory for use in production of a conjugate for direct fluorescent antibody tests. Serums with an agar gel precipitin titer of 1/8 or higher generally produce a usable fluorescent antibody conjugate. Labeling gamma globulins with fluorescein isothiocyanate at a ratio of 1/150 resulted in satisfactory fluorescent antibody conjugates. Cultures of Vero cells infected with chlamydiae were found to be suitable for titration of the fluorescent antibody conjugates.

Effects of cortisone, cytochalasin B and cycloheximide on strains of Chlamydia psittaci in cell cultures

Vero and McCoy cell cultures were tested for their susceptibility to Chlamydia psittaci in the presence of several antimetabolites, such as cortisone acetate, cytochalasin B and cycloheximide. Vero cells were more susceptible than the McCoy cell cultures as demonstrated by cytopathic changes, fluorescent antibody activity, and titer of C. psittaci. Although all of the antimetabolites increased these parameters, a mixture of cortisone and cytochalasin B was the most effective.

Treatment of ifosfamide-induced urothelial toxicity by oral administration of sodium 2-mercaptoethane sulphonate (MESNA) to patients with inoperable lung cancer

The protective effect of oral administration of the thiol compound sodium 2-mercaptoethane sulphonate (MESNA) against urothelial toxicity induced by ifosfamide (IF) was tested in a group of 45 patients with inoperable lung cancer under treatment with IF (2250 mg/m2 on days 2-5) as part of a polychemotherapy regimen repeated in a 4-week cycle. MESNA was given orally on the days of treatment with IF in 3 doses of 840 mg/m2, each administered at 0 hr (= injection of IF), 4 hr and 8 hr p.i. Out of a total of 88 courses of this treatment we observed 10 episodes of asymptomatic microscopic haematuria and no episodes of gross haematuria. In this group of 45 patients under protection with MESNA there were 5 complete remissions and 9 partial remissions (total 31%). A further group of 25 patients under polychemotherapy with IF were treated by conventional prophylactic measures (raised fluid intake and forced diuresis). In this group there were 1 complete and 5 partial remissions (total 24%), but nearly all patients developed either gross haematuria and/or symptoms of bladder irritation (cystitis and pollakisuria). There were no appreciable differences between the MESNA series and the conventional prophylaxis series with respect to either haematological or systemic toxicity of the cytostatic treatment. Our results support the view that MESNA, given orally in conjunction with combined cytostatic regimens which include IF, simplifies the treatment and provides optimum protection for the urinary epithelium. Protection with oral MESNA is particularly suitable for outpatients.

Direct immunofluorescence tests with counterstains for detection of Chlamydia psittaci in infected avian tissues

Different methods of preparation and serological evaluation of rabbit globulins for use in fluorescent antibody conjugate and different methods of counterstaining with fluorescent antibody tests were evaluated for detection of Chlamydia psittaci in infected turkey tissues. The agar gel precipitin reaction was that chosen for testing and selecting antiserums to be used for fluorescein isothiocyanate conjugation. The fluorescent antibody staining was most pronounced with conjugate made from globulins precipitated with ammonium sulfate. A direct fluorescent antibody method with Evans blue counterstain correctly identified "coded" specimens of C. psittaci-infected and noninfected turkey air sacs. However, naphthalene black was superior to Evans blue as a counterstain when infected pericardial sacs were tested.

Optimal macroculture method for studying mitogenic stimulation of turkey lymphocytes

This report describes a method for culturing turkey lymphocytes in disposable, unwashed glass test tubes with Morton closures and for recovering lymphocytes on fiber glass filters with a cell harvester made of common laboratory equipment for assay of mitogenic stimulation. Optimal conditions for culture were established.

Tween 80: a marker for differentiation of hog cholera and bovine viral diarrhea viruses

Markers for differentiating hog cholera and bovine viral diarrhea viruses were studied using Tween 80, chloroform, trichlorotrifluoroethane and tri (n-butyl) phosphate. Attenuated A and virulent Ames strains of hog cholera virus were employed. Moreover, the NADL PK-15 cell culture adopted strain and low cell culture passaged Purdue strain of bovine viral diarrhea virus were used. These viruses were reacted with 2,500 micrograms/ml of Tween 80 for one hour at 37 degrees C. When attenuated A and virulent Ames strains of hog cholera virus with titers greater than 10(6) and 10(5) plaque forming units respectively, were reacted with Tween 80 the titer of each strains was reduced by approximately 10(4) plaque forming units of virus. When either strain of bovine viral diarrhea virus was reacted with Tween 80, virus was not detected.

Stabilization of hog cholera virus by dimethyl sulfoxide

The stability of hog cholera virus through five freeze-thaw cycles in the presence and absence of dimethyl sulfoxide was studied. In the absence of dimethyl sulfoxide the hog cholera virus titer was reduced 52% to 91% following successive freezing and thawing cycles. However, when dimethyl sulfoxide was added to the viral suspension the virus titer appeared to remain the same after the same number of freezing and thawing cycles.

Pathologic features of chronic pneumonia in pigs with experimentally induced African swine fever

Chronic pneumonia developed in 14 pigs inoculated with an attenuated strain of African swine fever (ASF) virus. The pathogenesis of the pneumonia was as follows: (1) Interalveolar septums became thickened by accumulation of lymphocytes and monocytes; (2) lung developed focal areas of lymphocytes and macrophages; (3) necrosis began abruptly in these foci, beginning with the cells in the alveolar lumens, developing in centrifugal direction, and eventually affecting all structures in its path; (4) necrotic tissue became calcified; and (5) a mantle of mononuclear cells (including plasma cells) and fibrous tissue formed around the necrotic area. Viremia occurred in the 14 pigs at postinoculation day (PID) 14, and precipitating antibody was increased significantly at PID 58.

Differentiation among strains of goat mycoplasma by incident light immunofluorescence

Antigenic differentiation between strains of goat mycoplasma was studied by direct fluorescent antibody reactions employing incident (vertical) ultraviolet light. Agar colonies of the mycoplasma grown in petri dishes were fixed by alcohol in situ, and stained with conjugated globulin before examination with ultraviolet light. The fluorescent antibody (FA) conjugate against Vom strain of Mycoplasma mycoides var. capri was Vom strain-specific, no cross reaction with Mexico, Connecticut, or Maryland strains. Similarly, the Mexico strain conjugate was specific for colonies of Mexico, and did not cross with the Vom, strain. Additionally, the conjugate of the PG-2 strain of Mycoplasma agalactiae, which was specific for the colonies of PG-2 was refractory for the strain #99 of M. agalactiae. It was therefore possible to utilize an immunofluorescent technique (incident ultraviolet light) to demonstrate differences among strains of M. mycoides var. capri and M. agalactiae.

Vesicular lesions produced in guinea pigs by a Staphylococcus aureus strain

A bacterium isolated from vesicular lesions on foot pads of guinea pigs reproduced lesions similar to those seen in experimental infections of guinea pigs with foot-and-mouth disease virus. (FMDV). These bacterial lesions were produced with an inactivated FMDV suspension. Identification as Staphylococcus aureus was determined by growth characteristics on nutrient and blood agar, Gram staining, fermentation of mannitol and coagulase positive reactions. In addition, the organism was sensitive to concentrations of penicillin and streptomycin commonly used in laboratory diluents.

Incident light immunofluorescence of alcohol-fixed colonies of ruminant mycoplasma

Two species of ruminant mycoplasma colonies had to be fixed in ethyl alcohol so that incident immunofluorescence method could be applied. In addition, the stain reaction had to be kept for 90 minutes at 37 degrees C. This fluorescent antibody (FA) method was developed to identify colonies of Vom strain of Mycoplasma mycoides var. capri, V-5 strain of M. mycoides var. mycoides, and PG-2 strain of M. agalactiaeon agar, using fluorescent ultraviolet light. Fluorescence was not demonstrated when heterologous conjugates or normal rabbit serum conjugate were applied but the reaction appeared to be specific for each strain of mycoplasma. The FA method was able to differentiate specific mycloplasma colonies in mixed cultures.

Comparative study of agar mediums for propagation of ruminant mycoplasma

A brain heart infusion agar supplemented with 16.7% rabbit serum (BHIR) was found the most suitable for the culturing of ruminant mycoplasma. Gourlay medium and Perreau medium (4, 5) were not suitable for growth of Mycoplasma mycoides var. mycoides or M. agalactiae, but were satisfactory for M. mycoides var. capri. Four strains of M. mycoides var. mycoides, three strains of M. agalactiae and three strains of M. mycoides var. capri were grown in our laboratory.

Detection of African horsesickness viral antigens in tissues by immunofluorescence

The fluorescent antibody reaction was studied in tissues of ponies infected with African horsesickness virus (AHSV). Lung, spleen, lymph node, liver, skeletal muscle, intestine, stomach, nerve ganglion and kidney were sectioned and stained by the direct fluorescent antibody technique (FA). Fluorescence was demonstrated only in the spleen and could be inhibited by using unconjugated antiserum.