Developing a socio-economic measure to monitor access to tuberculosis services in urban Lilongwe, Malawi.

OBJECTIVES: To develop locally appropriate measures of poverty for the National Tuberculosis Programme (NTP), Malawi, and to assess access to tuberculosis (TB) services by different socio-economic groups by establishing a socio-economic profile of current TB patients DESIGN: A quantitative proxy measure of poverty was developed through regression analysis of data from the 1998 national Malawi Integrated Household Survey. A qualitative assessment of poverty was conducted in poor and non-poor settlements in urban Lilongwe to identify key indicators of socio-economic status. Both quantitative and qualitative indicators were used to assess the socioeconomic status of 179 TB patients who participated in a cross-sectional survey. FINDINGS: The proxy measure of poverty and the qualitative indicators demonstrated similar ability to measure the poverty status of patients. The poverty head count among patients using the quantitative and qualitative indicators were 78% and 70%, respectively. Geographical analysis showed that 60% were from non-poor areas and only 15% (26/139) were from squatter settlements. CONCLUSION: This study established a strategy for monitoring access to TB services using a proxy measure of poverty and qualitative indicators. This is a vital first step in developing an evidence base for pro-poor equitable TB services.

Auditing the new decentralised oral treatment regimens in Malawi.

SETTING: All 44 non-private hospitals in Malawi treating tuberculosis (TB) cases in which oral regimens were used allowing patients during the initial phase to receive directly observed treatment (DOT) from health centres or guardians at home. OBJECTIVES: A country-wide audit of the oral regimens to determine: 1) TB ward bed occupancy rates, 2) patient DOT options, 3) patients' knowledge of treatment and 4) treatment outcomes compared to those obtained with previous treatment regimens. DESIGN: Retrospective data collection using registers and treatment cards. Prospective interviews with patients. Inspections of TB wards. RESULTS: There were 1513 TB beds occupied by 807 (53%) TB patients. Over 50% of 4793 patients registered with different types of TB chose guardian-based DOT. For 266 patients with pulmonary TB the correct knowledge about total duration of treatment (45%), all three DOT options (62%) and the months for giving follow-up sputum (16%), was poor. There were differences in treatment outcomes between TB patients on oral compared with previous regimens. With oral regimens, rates of unknown outcome were high. CONCLUSION: Oral treatment regimens are associated with reduced bed occupancy rates on TB wards. However, rates of unknown outcome are increased, and TB control is therefore weakened.

Perceptions and experiences of health care seeking and access to TB care--a qualitative study in rural Jiangsu Province, China.

This study aims to obtain an in-depth understanding of factors that influence the health seeking behavior of TB patients, and access to tuberculosis (TB) care in counties with or without National TB Control Program (NTP) in rural China. Sixteen focus group discussions (FGDs) composed of TB patients and health care providers were held. Content analysis showed perceptions that financial difficulties influence health care-seeking behavior of TB patients in both program and non-program counties. Female and elderly patients were perceived to be more reluctant to seek health care and to seek care for cough from village health stations rather than general hospitals. Many TB patients said they could not afford the cost of TB care, even where services were subsidized. Fee-for-service incentives of health care providers and their ability to make a correct TB diagnosis were also perceived to influence patient access to TB care. Inappropriate treatment of cough patients was perceived to increase the risk of missing smear-positive diagnoses.

Using a bus service for transporting sputum specimens to the Central Reference Laboratory: effect on the routine TB culture service in Malawi.

SETTING: All non-private hospitals in Malawi that registered TB cases in 2001, during which there was a bus service for transporting sputum specimens to the Central Reference Laboratory (CRL) for mycobacterial culture and drug sensitivity testing (CDST). OBJECTIVES: To determine the performance of the system of collecting and processing sputum specimens from patients with recurrent smear-positive pulmonary TB through to CDST. DESIGN: Structured interviews with TB Officers, and retrospective data collection using TB and laboratory registers. RESULTS: There were 964 patients with recurrent smear-positive PTB. TB Officers took responsibility for collecting and transporting sputum to the CRL, and 73% reported using the bus service. Sputum specimens from 384 (40%) patients arrived at the CRL. Of these, 40% were found to have negative concentrated smears at the CRL, and 36% of specimen sets arriving at CRL were successfully cultured for DST. Most specimens had been collected after the start of anti-tuberculosis treatment. Although delays in collection adversely affected culture, only 43% of specimen sets collected on or before the first day of treatment yielded Mycobacterium tuberculosis. CONCLUSION: Problems were identified at all stages of the system and strategies to remedy these are being put in place.

Management and outcome of tuberculosis patients who fail treatment under routine programme conditions in Malawi.

SETTING: All 43 non-private hospitals (three central, 22 district and 18 mission) in Malawi that registered and treated TB cases between 1 July 1999 and 30 June 2000. OBJECTIVES: To determine 1) the number of new smear-positive PTB patients who failed treatment, 2) the management of patients who failed, 3) their treatment outcome and 4) culture and drug sensitivity results. DESIGN: Retrospective data collection using TB registers and laboratory culture and drug sensitivity registers. RESULTS: Ninety patients failed treatment, 60 (67%) at 5 months and 30 (33%) at the end of treatment. Sixty-four (71%) failure patients were registered and commenced on anti-tuberculosis treatment. Of these, 95% were registered in the same hospital as before, 89% were given a different TB registration number, 67% were correctly registered as 'failures' and 61% were treated within one month of failing the previous regimen. Forty-eight (75%) re-treated patients were cured. Only 31 (34%) of the 90 patients had sputum sent for culture and drug sensitivity testing. In 11 patients with cultures of M. tuberculosis, eight were fully sensitive and three had mono-resistance to isoniazid. CONCLUSION: While the outcome of failure patients who start retreatment is good, there are several programmatic deficiencies that need to be corrected.

Characteristics, management and outcome of patients with recurrent tuberculosis under routine programme conditions in Malawi.

SETTING: All 43 non-private hospitals in Malawi, which registered TB cases between 1 July 1999 and 30 June 2000. OBJECTIVES: To determine 1) the characteristics, management and treatment outcome, 2) timing of the previous episode of TB, and 3) pattern of drug resistance in patients registered with recurrent smear-positive pulmonary TB. DESIGN: Retrospective data collection using TB registers and laboratory culture and drug sensitivity registers. RESULTS: There were 748 recurrent patients; data were available for 747. Of these, 487 (65%) successfully completed a re-treatment regimen, 185 (25%) died and the remainder had another outcome. Information about previous TB was recorded for 491 (66%) patients. In 286 (58%) there were 2 years or less between completing and re-starting treatment. Only 307 (41%) patients had sputum sent for culture and drug sensitivity tests. In 164 patients with cultures of Mycobacterium tuberculosis, 122 (81%) were fully sensitive, 25 (15%) had resistance to isoniazid and/or streptomycin, and 6 (4%) had resistance to isoniazid and rifampicin (MDR-TB). CONCLUSION: Patients with recurrent TB had acceptable treatment outcomes, and most had fully sensitive organisms. Over half had recurrent TB 2 years or less after completing treatment. Ways to prevent recurrence need to be investigated and implemented in the field.

Developing operational research capacity in hospital tuberculosis control officers in Malawi.

SETTING: The National TB Control Programme (NTP) of Malawi. OBJECTIVES: To describe 1) the way in which a generic operational research project was developed and implemented by hospital TB officers (TBOs), 2) the outcome in terms of research work completed, data analysed and papers written up, and 3) the results of the research project. DESIGN: A descriptive study of assessing diagnostic processes in patients labelled as TB suspects who had been admitted to general hospital wards over 4 weeks. RESULTS: A total of 25 TBOs were trained in developing the research protocol: 19 performed satisfactory work, 17 attended an analysis/paper writing workshop and 11 submitted a research paper. The data of five papers were collated. Of 900 hospital admissions, 153 (17%) were TB suspects, of whom 37% were diagnosed with TB, 38% were discharged with another diagnosis and 25% died or absconded during investigations. CONCLUSION: This first attempt at developing a research capacity in hospital TB officers in Malawi was partially successful, and may, through local dissemination and feedback, help to improve the speed of TB diagnosis in hospital in-patients.

Diurnal fluctuations in corneal topography 10 years after radial keratotomy in the Prospective Evaluation of Radial Keratotomy Study.

PURPOSE: To correlate clinically observed fluctuations in manifest refraction, visual acuity, keratometry, and intraocular pressure (IOP) with changes in the anterior corneal surface as measured by videokeratography in patients 10 years after radial keratotomy (RK). SETTING: Four clinical centers in the United States that participated in the Prospective Evaluation of Radial Keratotomy (PERK) study. METHODS: Thirty-two eyes of 20 PERK patients who noted diurnal fluctuations in vision had clinical examination and videokeratography (TMS-1, Computed Anatomy Inc.) in the morning and evening of the same day a mean of 10.3 years (range 7.8 to 11.7 years) after RK. The videokeratographs were analyzed in terms of various indexes generated by custom-designed software. Morning-to-evening changes in the means of the various clinical and videokeratographic values were assessed using pairwise methods. RESULTS: The mean increase in myopia was 0.36 diopters (D) +/- 0.58 (SD) from morning to evening (P < .01). Analysis of the videokeratographs showed a corresponding increase in average corneal power (ACP), reflecting a steepening of 0.52 +/- 0.45 D (P < .001). The change in ACP was correlated with a change in the manifest spherical equivalent refraction (R = 0.39, P = .03) and a change in best spectacle-corrected visual acuity (R = 0.38, P = .03) over the same period. Similarly, simulated keratometry (SimK) readings correlated with the change in the manifest spherical equivalent refraction (R = 0.38, P = .03 for SimK1; R = 0.37, P = .35 for SimK2; R = 0.4, P = .02 for average SimK), although the standard clinical keratometric data did not (P = .26 for K1, P = .11 for K2, and P = .09 for the mean K). The elevation depression magnitude, a measure of the low-frequency irregularities of the cornea, showed a decrease of 0.32 +/- 1.59, which also correlated with the change in the manifest spherical equivalent refraction (R = 0.37, P = .04). Intraocular pressure tended to decrease from morning to evening (mean change of -0.97 +/- 3.29 mm Hg), but the difference was not significant. Variations in IOP in individual patients, however, were correlated with changes in the manifest spherical equivalent refraction (R = 0.37, P = .04). CONCLUSIONS: Diurnal fluctuations in corneal topographic indexes can be used to evaluate the diurnal fluctuations in refraction and visual acuity after RK. The study findings provide statistical support for the idea that IOP contributes to the diurnal fluctuation in visual acuity after RK.

Plasticity of immune responses suppressing parasitemia during acute Plasmodium chabaudi malaria.

gammadelta T cells have a crucial role in cell-mediated immunity (CMI) against P. chabaudi malaria, but delta-chain knockout (KO) (deltao/o) mice and mice depleted of gammadelta T cells with mAb cure this infection. To address the question of why mice deficient in gammadelta T cells resolve P. chabaudi infections, we immunized deltao/o mice by infection with viable blood-stage parasites. Sera from infection-immunized mice were tested for their ability to protect JHo/o, deltao/o double KO mice passively against P. chabaudi challenge infection. The onset of parasitemia was significantly delayed in mice receiving immune sera, compared with saline or uninfected serum controls. Immune sera were then fractionated into Ig-rich and Ig-depleted fractions by HPLC on a protein G column. Double KO mice were passively immunized with either fraction and challenged with P. chabaudi. The onset of parasitemia was significantly delayed in recipients of the Ig-rich fraction compared with recipients of the Ig-poor fraction of immune sera. We conclude that deltao/o mice, which are unable to activate CMI against the parasite, suppress P. chabaudi infection by a redundant Ab-mediated process.

Species specificity in the chemical mechanisms of organophosphorus anticholinesterase activity.

Structure-activity relationships reveal that the two principal determinants of anticholinesterase activity for various organophosphorus insecticides are steric hindrance and the electrophilic strength of the phosphorus atom. The objective of the present investigation was to distinguish between the molecular properties governing species-related differences in organophosphorus sensitivity by comparing the physical-chemical relationships for the inhibition of brain acetylcholinesterase isolated from rats, chickens, or rainbow trout. A homologous series of five dialkyl p-nitrophenyl phosphates consisting of methyl through n-butyl and isopropyl were synthesized and characterized both chemically and biologically. Structure-activity correlations revealed that whereas steric hindrance is the principal factor governing inhibitory potency for rats and hens, the electrophilicity of the phosphorus atom is the principal determinant of anticholinesterase activity in trout. The inductive effect of successive methylene substitutions on the phosphoryl group is reflected by 13C and 31P NMR spectroscopy which correlates with anticholinesterase activity in trout, but not in rats or hens. The results provide the first indication for species-related differences in the molecular regulation of anticholinesterase activity, suggesting that the trout enzyme possesses a relatively weak nucleophilic center within a dimensionally restricted esteratic subsite. Species-specific distinctions in the molecular properties governing anticholinesterase activity provide novel design strategies for improving the selectivity of toxic organophosphorus insecticides.

Purification and properties of mitochondrial phosphoenolpyruvate carboxykinase from liver of Squalus acanthias.

Liver from Squalus acanthias (spiny dogfish), a representative elasmobranch, contains approximately 1.4 units (mumol/min) of phosphoenolpyruvate carboxykinase activity per gram and approximately 90% of the total units of activity are localized in the mitochondria. The mitochondrial phosphoenolpyruvate carboxykinase was isolated and characterized. The purified enzyme has properties generally similar to those found in mammalian and avian species. The enzyme has a molecular weight of approximately 70,000 and exists in a functional state as a monomer. The isolated enzyme displays a dual cation requirement (e.g., 6 mM Mg2+ and 10 microM Mn2+) for maximal activity; very little activity is observed when Mg2+ is present alone, and the maximal activity attained with Mn2+ alone (millimolar concentrations required) is significantly less than that observed under optimal conditions with both cations present. When assayed in the direction of oxalacetate formation there is a lag in product formation with time; the lag can be eliminated by the presence of 50 microM GTP (product). The Km for substrates is not affected by Mn2+ concentration, suggesting that the role of Mn2+ may not be related to substrate binding. The apparent Km for phosphoenolpyruvate (approximately 1 mM) is substantially higher than that reported for phosphoenolpyruvate carboxykinase from other species. The activity of phosphoenolpyruvate carboxykinase is increased 70% by physiological concentrations of urea. Maximal velocity of the reaction in the direction of oxalacetate formation is approximately half that of the reverse reaction.

Molecular determinants of the species-selective inhibition of brain acetylcholinesterase.

The objective of this investigation was to distinguish which of the catalytic features of enzyme action is principally responsible for conferring the observed insensitivity of trout brain acetylcholinesterase (AChE; EC 3.1.1.7) to in vitro inhibition by organophosphates. The experimental design consisted of comparing the kinetic constants for the hydrolysis of a series of acylthiocholine substrates as well as the inhibition constants for a homologous series of dialkyl p-nitrophenyl phosphates among AChE from rats, hens, and trout. Chicken and rat brain AChE failed to distinguish between acetyl- and propionylthiocholine as inferred from the comparable Michaelis-Menten constants (Km), whereas trout brain AChE exhibited a much higher affinity for acetylthiocholine than for either of the two larger analogs. Diethyl p-nitrophenyl phosphate was the most potent inhibitor toward chicken and rat brain AChE, whereas the IC50 for the trout enzyme increased progressively between dimethyl and di-n-propyl p-nitrophenyl phosphate. The kinetic constants revealed that a significant determinant of inhibitor potency in the chicken and rat is steric exclusion as reflected by changes in the dissociation constant (Kd) which paralleled the changes in IC50 and ki. Conversely, Kd was 120- to 1450-fold higher and did not vary significantly for trout brain AChE. Instead, the phosphorylation rate constant (kp) for trout brain AChE decreased with progressive methylene substitutions. The kinetic data suggest that trout brain AChE not only possesses less steric tolerance, but also has a weaker nucleophile at the esteratic subsite, both of which may be important factors in conferring the observed insensitivity of trout to acute organophosphate intoxication.

Thromboxane synthesis and actions in isolated adrenergic nerve (pheochromocytoma-12) cells.

The synthesis of cyclooxygenase products by cultured adrenergic neuronal (pheochromocytoma-12) cells was investigated by measuring both the extent of conversion of [3H]arachidonic acid to prostanoids and the immunoreactive prostanoid concentrations in the bathing buffer. Statistically significant amounts of arachidonic acid metabolites migrated with prostaglandins (PGs) E (81 +/- 14 fmol) and F (68 +/- 13 fmol) and thromboxane B (49 +/- 12 fmol) on thin-layer chromatography plates after incubation of differentiated cells with 1 pmol of [3H]arachidonic acid. The conversion of arachidonic acid to these products was lower in undifferentiated cells, although PGE- and PGF-like metabolites were produced in significant amounts. Both immunoreactive PGE and thromboxane B were detected in the media of differentiated cells and their concentrations were elevated when the cells were exposed to arachidonic acid. The potential significance of the thromboxane production by pheochromocytoma-12 cells was investigated by examining the effect of a stable thromboxane mimetic, U46619, on potassium-stimulated norepinephrine release. The U46619 significantly enhanced norepinephrine release from potassium-depolarized cells. These results are indicative of PGE, PGF and thromboxane production by isolated adrenergic neuronal tissue. A thromboxane receptor agonist also was observed to potentiate norepinephrine release.

Have Liley charts outlived their usefulness?

Fetal blood and amniotic fluid samples were obtained fetoscopically from 59 rhesus-isoimmunized pregnancies at 18 to 25 weeks' gestation. Fetal hemoglobin was measured and amniotic fluid optical density deviation at a wavelength of 450 nm determined. Two sets of normal reference values for optical density at 450 nm and fetal hemoglobin at 16 to 36 and 16 to 25 weeks were established from 475 amniotic fluid and 153 fetal blood samples obtained from pregnancies not complicated by fetal hemolysis. As expected, there was a significant linear correlation between the degree of fetal anemia and the amniotic fluid optical density at 450 nm in rhesus-isoimmunized pregnancies. However, the values of optical density at 450 nm were widely scattered, thereby limiting their ability to predict accurately the severity of disease in these second-trimester pregnancies. In 25 of the patients, the value of optical density at 450 nm was determined at 6 to 16 days before fetoscopy. The severity of fetal anemia could not be predicted by the trend in optical density at 450 nm. These data suggest that the only reliable method to determine the severity of rhesus isoimmunization in the second trimester of pregnancy is the direct measurement of fetal hemoglobin.

The management of severe rhesus isoimmunization by fetoscopic intravascular transfusions.

Twenty-five severely rhesus-isoimmunized fetuses, including 15 with hydrops fetalis, underwent a total of 77 intrauterine transfusions between 19 and 32 weeks' gestation. Fifty-eight of the procedures were fetoscopically directed intravascular transfusions, nine were ultrasound-guided intraperitoneal transfusions, and 10 were a combination of intravascular transfusion, fetal paracentesis, and intraperitoneal transfusion. The average number of antenatal procedures per patient was three (range, one to five). The survival rate for the 19 fetuses that received their initial intrauterine transfusion at or before 25 weeks' gestation was 84%; 11 of the 13 hydropic fetuses and five of the six fetuses without antenatal evidence of hydrops survived. In six cases hydrops fetalis was reversed in utero. The outcome in patients referred after 25 weeks' gestation was poor; neither of the two hydropic fetuses and only two of the four nonhydropic ones survived, which suggests the importance of early referral to a team experienced in the management of this problem. However, most of these fetal losses occurred early in the series. Seven of the 20 neonates were hydropic, and nine had severe thrombocytopenia (platelet count, less than 50,000 X 10(6)/L). The mean cord blood hematocrit and bilirubin of the neonates were 25.1% and 82 mumol/L, respectively. The babies required a total of 69 exchange transfusions (range, 0 to 9) and 68 simple transfusions (range, 0 to 25). One newborn infant who had had ultrasound evidence of hydrops fetalis at 22 weeks' gestation did not require any exchange transfusions. Nine patients required intermittent positive pressure ventilation (eight had respiratory distress syndrome and one had apnea) for a range of 1 to 86 days. The neonatal survival rate was 90% (18/20).

Direct intravascular fetal blood transfusion by fetoscopy in severe Rhesus isoimmunisation.

Two fetuses with severe anaemia due to rhesus incompatibility each received two early blood transfusions (between 23 and 25 weeks) by fetoscopy. The blood was given directly into an umbilical vessel, either at the umbilicus or at the placental cord insertion. Fetal blood samples were taken before and after transfusion to assess the haematological status of the fetus. One grossly hydropic fetus survived.