The role of HLA antigens in the development of paracoccidioidomycosis

BACKGROUND

Paracoccidioidomycosis is a systemic granulomatous disease that involves primarily the lungs and may disseminate to other organs and systems. It is caused by Paracoccidioides brasiliensis, a fungus that exhibits reversible thermal dimorphism and whose natural habitat is presently unknown. There are two main clinical forms: the acute (subacute) juvenile form and the chronic adult form. The former runs a more rapid course and is more severe than the latter. This mycosis is found throughout Latin America. Brazil accounts for 80% of reported cases. Presumably P. brasiliensis thrives in humid and hot places, especially near forests or farms. The infection is endemic in certain areas, especially in Brazil, Colombia and Venezuela, where nearly 100% of the population show cutaneous paracoccidioidina positive skin tests, indicating previous contact with the fungus, although a small percentage show clinical manifestations of the disease.

METHODS

We compared the expression of HLA class I antigens in a healthy group (control) and in a group of patients with paracoccidioidomycosis (chronic adult form) using the Terasaki lymphocytotoxicity test modified by Amos for HLA antigen analysis.

AIMS

To discover indications of whether or not individual susceptibility to P. brasiliensis might depend on some specific immunological defect.

RESULTS

There is no evidence of association between a specific HLA antigen and paracoccidioidomycosis in the subjects studied. Further investigations are recommended.

Vascular oxidant stress early after balloon injury: evidence for increased NAD(P)H oxidoreductase activity

Available evidence for oxidative stress after angioplasty is indirect or ambiguous. We sought to characterize the pattern, time course, and possible sources of free radical generation early after arterial balloon injury. Ex vivo injury performed in arterial rings in buffer with lucigenin yielded a massive oxygen-dependent peak of luminescence that decayed exponentially and was proportional to the degree of injury. Signals for injured vs. control arteries were 207. 1 +/- 17.9 (n = 13) vs 4.1 +/- 0.7 (n = 22) cpm x 10(3)/mg/min (p <. 001). Data obtained with 0.25 mmol/l lucigenin were validated with 0. 005-0.05 mmol/l lucigenin or the novel superoxide-sensitive probe coelenterazine (5 micromol/l). Gentle removal of endothelium prior to injury scarcely affected the amount of luminescence. Lucigenin signals were amplified 5- to 20-fold by exogenous NAD(P)H, and were >85% inhibited by diphenyliodonium (DPI, a flavoenzyme inhibitor). Antagonists of several other potential free radical sources, including xanthine oxidase, nitric oxide synthase, and mitochondrial electron transport, were without effect. Overdistension of intact rabbit iliac arteries in vivo (n = 7) induced 72% fall in intracellular reduced glutathione and 68% increase in oxidized glutathione, so that GSH/GSSG ratio changed from 7.93 +/- 2.14 to 0. 81 +/- 0.16 (p <.005). There was also 28.7% loss of the glutathione pool. Further studies were performed with electron paramagnetic resonance spectroscopy. Rabbit aortas submitted to ex vivo overdistension in the presence of the spin trap DEPMPO (5-diethoxy-phosphoryl-5-methyl-1-pyrroline-N-oxide, 100 mmol/l, n = 5) showed formation of radical adduct spectra, abolished by DPI or superoxide dismutase. Computer simulation indicated a mixture of hydroxyl and carbon-centered radical adducts, likely due to decay of superoxide adduct. Electrical mobility shift assays for NF-kappaB activation were performed in nuclear protein extracts from intact or previously injured rabbit aortas. Balloon injury induced early NF-kappaB activation, which was decreased by DPI. In conclusion, our data show unambiguously that arterial injury induces an immediate profound vascular oxidative stress. Such redox imbalance is likely accounted for by activation of vessel wall NAD(P)H oxidoreductase(s), generating radical species potentially involved in tissue repair.

Dental caries and fluorosis prevalence study in a nonfluoridated Brazilian community: trend analysis and toothpaste association

The main purpose of this study is to compare data from previous surveys to current prevalence rates of dental caries and dental fluorosis in eleven- and twelve-year-olds in a non-fluoridated Brazilian community (< 0.2 ppm F). This study also assesses the possible association between use of fluoride toothpaste and the prevalence of dental caries and dental fluorosis. The sample subjects are randomly selected schoolchildren who were examined with a dental probe and buccal mirror under natural light. The intra-examiner error was calculated, using Kappa statistics (K tau 0.85). The results showed that between 1991 and 1997 there was a 56.7 percent decrease in the prevalence of dental caries and an 80.1 percent increase in dental fluorosis. Children with dental fluorosis were 1.75 times more likely to be free of caries (OR = 1.75-CI:0.43, 6.68). Children who started using fluoride toothpaste before the age of three were 4.43 times more likely to have dental fluorosis than those who started using it after the age of three (OR = 4.43-CI:0.51, 99.61). The results of the cross-sectional surveys conducted with schoolchildren in 1991, 1995, and 1997 suggest a continuing decrease in the prevalence of dental caries and an increase in the prevalence of dental fluorosis in this nonfluoridated Brazilian town.

Cost-effectiveness study of a school-based sealant program

A nonprofit private dental clinic provides free dental treatment for children up to the age of eighteen years. In order to expand its services to reach more children, a school-based sealant program using dental auxiliary personnel was organized. This paper evaluated the performance of the school-based program during 1991 by comparing the costs of the school-based program with the costs of the sealants placed in the clinic in twelve months. Costs were calculated based on 1991 expenditures, and effectiveness rates were estimated from dental literature on sealants. The cost of saving one tooth-surface from decaying within a six-year period at the school and the clinic was $65 and $42 with an average sealing time per tooth surface of 18 and 12.5 minutes, respectively. Despite the relatively lower cost of personnel, the school program cost was 35 percent higher than at the clinic. Nevertheless, if hidden costs, such as transportation, time off work, and waiting time for those attending the clinic were considered, costs could be comparable or even higher for the clinic. The main goal of this paper is to explore a methodology to compare programs of different nature, and critically evaluate the results.

Cloning and characterization of a putative human d-2-hydroxyacid dehydrogenase in chromosome 9q

There is little information on d-isomer-specific dehydrogenases in humans. Identification of d-2-hydroxyglutaric aciduria, an inherited metabolic disorder associated with severe neurological dysfunction, highlights the role of d-isomers in human metabolism. The possibility of a defect in d-2-hydroxyglutarate dehydrogenation prompted us to employ E. coli d-2-hydroxyacid dehydrogenase cDNA to search the human expressed sequence tags database. Two human EST homologues were retrieved and sequenced. Analysis showed the two clones were identical with 1258 nucleotides encoding 248 amino acids of the putative human d-2-hydroxyacid dehydrogenase. It was highly homologous to bacterial d-2-hydroxyacid dehydrogenases (46%), d-phosphoglycerate dehydrogenase (38%), and formate dehydrogenase (36%) at the amino acid level. The gene is expressed ubiquitously in tissue, most abundantly in liver, and was mapped to chromosome 9q between markers WI-3028 and WI-93330. To our knowledge this is the first cloning and characterization of the cDNA for a human d-isomer specific NAD(+)-dependent 2-hydroxyacid dehydrogenase.

Aspirin or heparin in acute stroke

Acute stroke treatment using aspirin and/or heparin was studied in the International Stroke Trial (IST) and Chinese Acute Stroke Trial (CAST) which randomised over 40,000 patients altogether. Combining the results demonstrated that aspirin (150-300 mg) given within 48 h of the onset of stroke produced a small but significant improvement in outcome (death or dependency) 4 weeks to 6 months after stroke of about 1 patient per 100 treated. There was a significant reduction in recurrent ischaemic stroke of similar degree, which was not associated with significant increase in cerebral haemorrhage. Therefore, aspirin should be used as early secondary prevention against recurrent stroke, after excluding cerebral haemorrhage by scanning the patient. Heparin does not improve clinical outcome after stroke even in patients in atrial fibrillation. It decreased recurrent ischaemic stroke significantly in IST, but at the cost of a significant increase in cerebral haemorrhage. Low molecular weight heparins and heparinoids have not proved any more beneficial. Therefore, heparin does not appear to be a useful routine therapy in acute stroke. The use of heparin should, therefore, be limited to patients at high risk of deep vein thrombosis or early recurrence.

[Job satisfaction in Portuguese physicians in general medicine]

OBJECTIVES

To identify the major areas of GP's job satisfaction and dissatisfaction and to study the most important reasons of GP's job dissatisfaction.

DESIGN

Cross-section study. Survey by mail and personal interview.

PARTICIPANTS

1.097 GPs.

SETTING

Northern region of the Portuguese Medical Association.

MEASUREMENTS AND MAIN RESULTS

46% of the 385 respondent GPs are dissatisfied with the overall job satisfaction. The rate of pay is the dimension that generates more job dissatisfaction, as also the major area that has the highest level of job dissatisfaction and has significant association with the overall job satisfaction, but has not predictive association with it. The majority declares that it is more adequate a payment system with fixed and variable components. The same regimen of work may generate satisfaction in some GPs, and dissatisfaction in others. Both the authoritarian leadership behavior and the laissez-faire style are almost nonexistent in the health centers of the satisfied GPs, but predominate in the health centers of the dissatisfied GPs. Those leadership styles are not desired by the dissatisfied GPs.

CONCLUSIONS

The rate of pay generates more job dissatisfaction, but has not predictive association with the overall job satisfaction. The authoritarian leadership behavior and the laissez-faire style are by themselves generators of GP job dissatisfaction, even if the regime of work by itself does not generate it.

Measurement of initial N-acetyl aspartate concentration by magnetic resonance spectroscopy and initial infarct volume by MRI predicts outcome in patients with middle cerebral artery territory infarction

BACKGROUND AND PURPOSE

(1)H MR spectroscopy can be used to study biochemical changes occurring in the brain in stroke. We used it to examine the relationship between metabolite concentration (N-acetyl aspartate [NAA], lactate, cholines and creatines), size of infarct, clinical deficit, and 3-month clinical outcome in patients with middle cerebral artery (MCA) territory infarction.

METHODS

Thirty-one patients with acute MCA territory infarction were recruited within 72 hours of the onset of symptoms. Single-voxel short echo time stimulated echo acquistion mode spectroscopy was used to obtain metabolite data from the infarct core. Metabolite concentrations were determined with use of variable projection time domain-fitting analysis. Infarct size was determined with T2-weighted images. Patient outcome groups at 3 months were "independent," "dependent," or "dead."

RESULTS

All patients (100%; 95% CI 75% to 100%) who had an infarct >70 mL did poorly. Eighteen of 20 patients (90%; 95% CI 68% to 99%) with a core NAA concentration <7 mmol/L did poorly at 3 months, whereas 7 of 11 patients (64%; 95% CI 31% to 89%) with an initial NAA concentration >7 mmol/L did well. Combining these results showed that all patients who had an initial infarct volume >70 mL did poorly, irrespective of the NAA concentration. Of those patients with infarcts <70 mL, those who had a core NAA concentration >7 mmol/L did well (88%; 95% CI 47% to 100%), whereas those with a lower NAA concentration did poorly (80%; 95% CI 44% to 97%). There was no association between other metabolite concentrations and outcome.

CONCLUSIONS

Infarct volume and NAA concentration can together predict clinical outcome in MCA infarction in humans.

Rat angiotensin-converting enzyme promoter regulation by beta-adrenergics and cAMP in endothelium

To shed light on mechanisms of angiotensin-converting enzyme (ACE) upregulation, we used a rabbit endothelial cell model to characterize intracellular pathways of beta-adrenergic stimulation. In these cells, ACE activity is increased by isoproterenol (ISO). The stably transfected 1273-bp ACE promoter is stimulated by ISO in the presence of isobutyl methylxanthine. This effect is abolished by propranolol. Promoter stimulation is mimicked by cholera toxin, forskolin, and 8BrcAMP, but not by 8BrcGMP. Promoter stimulation by ISO and isobutyl methylxanthine is blocked by protein kinase A inhibitors, indicating that beta-adrenergic stimulation of the ACE gene depends on phosphorylation of protein kinase A targets. Activation by cAMP, resistance to phorbol ester, and lack of synergism between cAMP and phorbol ester suggest that promoter regulation is due to cAMP responsive element rather than to activating protein-2 sequences. Okadaic acid potentiation of 8BrcAMP induction indicated that promoter activation by cAMP is regulated by phosphatases controlling activation of typical cAMP responsive element regulated genes. In summary, beta-adrenergic activation of rat ACE promoter is specific; uses G(s) proteins, adenylyl cyclase, protein kinase A; and probably includes cAMP responsive element-like sequences.

Retention and caries prevention of Vitremer and Ketac-bond used as occlusal sealants

PURPOSE

To assess the retention and caries incidence of Vitremer (resin-modified glass ionomer) and Ketac-bond (conventional glass ionomer cement), used as occlusal sealants, after 6 and 12 months placement.

MATERIALS AND METHODS

The sample consisted of 200 school children, 6-8 years old with sound and unsealed permanent first molars. They were divided into three groups: (a) control group (n = 432 teeth); (b) Vitremer experimental group (n = 200 teeth), and (c) Ketac-Bond experimental group (n = 200 teeth). In the experimental groups, Vitremer was applied on teeth 16 and 46 whereas Ketac-Bond was applied on 26 and 36.

RESULTS

The total retention rates for Vitremer after 6 and 12 months were 59% and 36%, respectively. For Ketac-Bond, the total retention rates were 24% and 15%, respectively. No dental caries was recorded during the 12 months for both experimental groups. When effectiveness was measured by sealant retention, there was a significant difference between Vitremer and Ketac-Bond after 6 (P < 0.01) and 12 months (P < 0.05). When effectiveness was measured by caries prevention, no significant difference was found between experimental groups, even when the sealants were partially or totally lost. There was no development of carious lesions after 1-year placement of sealants, but there was a significant difference between experimental and control groups (P < 0.01).

[Systemic arterial hypertension and psychiatric morbidity in the outpatient care setting of a tertiary hospital]

Arterial hypertension is one of the most important risk factor for cardiovascular disease, the main cause of death in Brazil. Hypertensive patients that have treated in tertiary care hospitals have shown elevated co-morbidity including psychiatric disturbances. Our objective is to study psychiatric co-morbidity among severe hypertensive patients. This study was performed in an out-patient clinic of tertiary medical care setting. Forty-one patients were enrolled in this research (26 women, 15 men). They were submitted to a clinical interview and answering the PRIME-MD, a specific questionnaire for diagnosis of psychiatric disturbances (by a general practitioner). Frequencies of psychiatric disturbances were different in men and women: 63.4% of the women in this study showed some type of psychiatric disturbance versus 36.6% of men (p = 0.012). The majority of the diagnosis were mood disturbances, mainly depression associated or not with anxious disturbances. Mean age of psychiatric disturbance patients was 47.1 years versus 59.3 years in the patients without psychiatric disturbances (p = 0.0049), showing the presence of psychiatric disturbances in younger patients. Other factors as systolic arterial blood pressure, diastolic arterial blood pressure and body mass index did not show any differences associated with psychiatric disturbance. We conclude that there is a great co-morbidity between high complexity hospitals hypertensive patients and that this type of disturbance is more frequent in women and in younger patients.

A luciferase-engineered cell line for study of cAMP regulation in endothelial cells

cAREL is a cAMP-responsive endothelial cell line carrying a luciferase reporter gene introduced by stable transfection of a luciferase enhancer trap into rabbit aortic endothelial cells. Luciferase gene expression in cAREL was stimulated 233-fold by 8-BrcAMP. Treatment with the beta-adrenoceptor agonist isoproterenol induced a 7.0-fold increase in luciferase expression, which was partially blocked by either beta1- or beta2-adrenoceptor antagonists and totally blocked by propranolol and by a combination of beta1- plus beta2-adrenoceptor antagonists. Receptor stimulation was mimicked by cholera toxin, forskolin, 8-BrcAMP, and isobutylmethylxanthine but not by 8BrcGMP, dexamethasone, or phorbol 12-myristate 13-acetate. Stimulation by isoproterenol was completely blocked by H-89, a protein kinase A inhibitor. cAREL was also stimulated by A-23187, and this effect was abrogated by EGTA and H-89. cAREL is the first cAMP-sensitive endothelial cell line described, and it can be useful as a positive control, as a model for cAMP regulation, as a background to genetic introduction of receptors, as an indicator of intracellular pathway activation, and as a tool to investigate cAMP effects on other signaling pathways.

[Antihypertensive treatment. Prescription and cost of drugs. Survey in a tertiary care hospital]

PURPOSE

To study the most prescribed anti-hypertensive drugs, evaluating their agreement with established guidelines and drug cost.

METHODS

One hundred and forty one (101 women, mean age = 53.3 years) hypertensive patients who searched spontaneous attention were interviewed in a tertiary-care hospital. The inclusion criteria were previous diagnosis of hypertension and non cardiovascular complaints.

RESULTS

The majority of the 107 (75.9%) patients were on medical treatment. In those receiving monotherapy, thiazides were the most utilized drugs, followed by methyldopa, ACE inhibitors, calcium channel-blockers, and beta-blockers. The association with thiazides (26.3%) followed the same preference. The second most prescribed drug, methyldopa, was the more expensive. Fifty percent of the patients purchased the drugs at their own expense.

CONCLUSION

A preference for prescription of expensive drugs for hypertension was detected in this sample in Brazil. This does not agree with major guidelines, mainly the V-JNC, which suggest thiazides and betablockers as first choice drugs for hypertensives with no complications or associated comorbidity.

Effect of an elemental diet on the mechanical resistance and morphology of the colon in rats

The aim of this study was to investigate the effect of an elemental diet (ED) on colonic morphology and mechanical resistance. Rats received either laboratory chow (control group; n=6) or oral total parenteral nutrition solution (ED group; n=6). After 14 d the colon was measured and weighed with and without the contents. Bursting pressure was determined in the right and left colon. Samples of these segments were examined histologically. Crypt depth and wall width (WW) were measured. All animals gained body weight. The bowels of ED-fed animals were shorter (23.7+/-1.6 versus 19.7+/-1.8 cm; P=0.003) and weighed less than the controls either with (10.3+/-0.8 versus 5.0+/-0.7g, P < 0.001) or without (4.9+/-0.9 versus 2.6+/-0.3 g; P < 0.001) feces. Bursting pressure was lower in animals receiving ED compared with controls (right colon: 250+/-30 versus 200+/-30 mm Hg; P=0.03; left colon: 195+/-22 versus 160+/-14 mm Hg; P=0.009). Crypt depth and WW were significantly shorter in the left colon in the ED group. Administration of ED promotes lack of mechanical resistance and atrophy of the colonic wall, especially in the left colon.

[Validation of a questionnaire for the diagnosis of headache in an outpatient clinic at a university hospital]

Headache is a common complaint with a high prevalence in ambulatory settings. The physical and neurological examinations are frequently normal. The use of questionnaires as a screening methods for patients with primary headache could facilitate the diagnosis in non-specialized medical centers. In the present study, we used a questionnaire, based on the IHS criteria and modified by the authors, applied to 204 patients from the outpatient clinic of the Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. Half of the patients were submitted to a clinical interview. We compared the results of the questionnaire with the results of the medical interview (gold standard). Most of the headaches we studied were primary headaches (89.6%). The questionnaire revealed a sensitivity of 90.2% and specificity of 57.9% for migraine detection with a chance corrected agreement (kappa) of 0.47 and a positive predictive (PPV) value of 65.7% and a negative predictive value (NPV) de 86.8%. The sensitivity for tension-type headache detection was 60.8% and the specificity 87.1% with a kappa value of 0.49 and a PPV of 77.8% and a NPV of 75.9%. We conclude that this questionnaire can be used as a screening method for diagnosing headache and that it can be applied by non-medical personnel. This questionnaire could also be used for population studies.

[Vertebral osteomyelitis in children]

Vertebral osteomyelitis is an uncommon disease in children, presenting with signs and symptoms that, at least initially, make a correct diagnosis difficult to be achieved. The authors report five cases of vertebral osteomyelitis in children, describing its clinical and laboratory peculiarities. The usefulness of the different radiologic studies for the diagnosis and follow up of these patients is discussed. We confirm previous reports according to which, with adequate clinical and therapeutic management, the prognosis is good for most patients.

Herpes simplex virus type 2 in Brazil: seroepidemiologic survey

BACKGROUND

The incidence of genital herpes is increasing worldwide. Herpes simplex virus type 2 (HSV-2) is the most common cause of genital ulcerations among the sexually transmitted diseases (STDS). In order to investigate the sexual transmission of genital herpes infection in Brazil, the prevalence of specific antibodies to HSV-2, in populations of high and low risk for STDS was evaluated.

METHODS

The population at low risk for STDS was composed of 155 voluntary blood donors at the University Hospitals between February and August, 1994. The population at high risk for STDS was composed of 85 HIV-seropositive persons, consisting of homosexual and promiscuous heterosexual men. A group of 20 highly active prostitutes was also studied between May and July, 1994. All blood samples were screened using an enzyme-linked immunosorbent assay (ELISA) that detects type-specific antibodies to HSV-2 glycoprotein G. Before donating blood, all persons in the study group were given a questionnaire concerning risk factors for acquisition of STDS and suitable to show the socioepidemiologic characteristics of the subjects.

RESULTS

The prevalence of ELISA showing HSV-2 infections among HIV-seroposite persons, was 73% (P < 0.01). In the whole group at high risk for STDS, the prevalence was 72% (P < 0.05). Infection with HSV-2, as determined by seroprevalence, was significantly and independently associated with years of sexual activity, history of previous STDS, number of sexual partners in the previous month, number of pregnancies, and previous induced abortions, as well as the percentage of sexual acts involving receptive anal intercourse.

CONCLUSIONS

The current strategy for diagnosing genital HSV-2 infection misses many cases. Newly developed type-specific serologic methods can identify cases of unrecognized or subclinical infection. With the high seroprevalence rates detected, routine screening for HSV-2-specific antibodies should be considered in populations at high risk for STDS.

Human parvovirus B19 infection: clinical and epidemiological study of 24 cases

From March 1994 to November 1995 24 cases of human parvovirus B19 infection were seen at the Infectious Diseases Department of the Hospital Universitário Antônio Pedro, Niterói-RJ. Serum samples for IgM detection (capture enzyme immunoassay) were positive from the 1st to the 27th day after the onset of the exathema. The classical features of erythema infectiosum (slapped cheecked syndrome) were observed in 8 (33.3%) cases all of them children. Eight patients (6 adults and 2 children) presented a symmetrical polyartropathy, seen more frequently in women. These results show that B19 infection diagnosis is difficult when the disease does not present the classical features and because of the frequent involvement of the joints this infection should be considered in the differential diagnosis of early rheumatoid arthritis.

[Evaluation of the prevalence of dental caries in school-children from an urban area of Southeastern Brazil]

An epidemiologic survey of dental caries was undertaken in the town of Paulínia. S. Paulo state, south-eastern Brazil, in 1994, for the purpose of comparing the present prevalence with that registered during the previous study of 1980. The children examined numbered 1,416, were of both sexes and aged 7-14. Ten dentists, preciously trained, used DMF.T and DMF.S dental caries indexes. A level of prevalence of dental caries 67.8% below that of 1980 was found. Further, there had been an inversion of DMF.T index components. Whereas in 1980 the component caries was higher (69.5%), while the filing component prevailed (79.0%) in 1994. The missing tooth component has disappeared altogether in this recent survey.

Oral health and periodontal status in Brazilian elderly

A total of 104 elderly persons between the ages of 60 and 89 were examined at the "Geraldo de Paula Sousa" Health Center, São Paulo, State of São Paulo. The state of their oral health was very poor, insofar as 4.29 (71.5%) of the sextants were shown to be null, while 0.12 and 0.13 sextants showed deep periodontal pockets > or = 6 mm in the ages from 60-70 and more than 70 years of age, respectively. The level of knowledge about periodontal disease and dental plaque was very deficient; only about 52% of the population under study reported having visited a dentist in the last two years. We conclude that greater odontological attention is needed for the elderly age group, as there are no large-scale community service centers in Brazil for this population group.

Influence of Inoculum Density, Host, and Low-temperature Period on Delayed Hatch of Meloidogyne javanica Eggs

Most eggs of M. javanica hatch within several days when incubated in water. Those that do not are said to show delayed hatching. Several experiments were conducted to determine the effect of specific conditions on the percentage of eggs with delayed hatch. Six initial inoculum densities ranging from 100 to 20,000 eggs per pot did not influence egg hatch within a 45-day incubation period. In a 60-day test, the percentage of eggs hatching after more than 20 days was low for egg masses removed from carrot and okra and high for those from pepper and bean. Increasing exposure to cold temperature (8 C) from 7 to 30 days tended to delay hatch.

Inhibition of the calcium pump by high cytosolic Ca2+ in intact human red blood cells

1. The inhibitory effect of high intracellular calcium on the saturated Ca2+ efflux through the Ca2+ pump (Vmax) was investigated in intact human red cells. Cells were loaded with Ca2+ by exposure to the calcium ionophore A23187, at different external Ca2+ concentrations ([Ca2+]o). Ca2+ extrusion by the pump was followed after either ionophore removal or Co2+ addition. 2. fifty per cent inhibition of Vmax was obtained with total intracellular calcium ([CaT]i) of approximately 3 mmol/l cells. For any given initial Ca2+ load, Vmax showed no tendency to increase as [CaT]i was progressively reduced during Ca2+ efflux. This suggests that the pump Vmax was determined by the magnitude of the initial [Ca2+]i. 3. To estimate [Ca2+]i from [CaT]i in Co(2+)-loaded cells, the possible competition between Co2+ and Ca2+ for the known cytoplasmic Ca2+ buffers (alpha-buffers) was investigated first. Comparison between Ca2+ efflux after either Co2+ exposure or ionophore wash-out showed that the efflux patterns were essentially identical, down to the lowest measurable [CaT]i. This indicates that Co2+ does not compete with Ca2+ for the alpha-buffers. Hence, since [Ca2+]i = alpha [CaT]i, and alpha approximately 0.15-0.35, the initial [Ca2+]i load for 50% Vmax inhibition was between 0.4 and 1.1 mM. 4. Ancillary new findings demonstrated that, unlike the situation with alpha-buffers, Co2+ displaced Ca2+ from the cell-incorporated calcium chelator benz-2, and that benz-2 incorporation had no effect on Co(2+)-exposed Ca2+ pump desaturation. This validates the use of benz-2 to study Ca2+ pump kinetics in intact cells.

Estimation of pulmonary artery pressure by colour guided continuous wave Doppler in cases of ventricular septal defect and tricuspid regurgitation

The accuracy of a non-invasive estimation of systolic pulmonary artery pressure in 33 patients with ventricular septal defect and/or tricuspid regurgitation, by colour guided continuous wave Doppler was evaluated. The estimated pulmonary artery pressure correlated well with values obtained at cardiac catheterization (r = 0.93). Correlation was better in cases with ventricular septal defect (r = 0.98) than in cases with tricuspid regurgitation (r = 0.87). Pulmonary artery pressure was under-estimated in cases with mild tricuspid regurgitation, probably due to eccentricity of regurgitant jet in some of these cases.