Confidence intervals and sample-size calculations for the sisterhood method of estimating maternal mortality.

The sisterhood method is an indirect method of estimating maternal mortality that has, in comparison with conventional direct methods, the dual advantages of ease of use in the field and smaller sample-size requirements. This report describes how to calculate a standard error to quantify the sampling variability for this method. This standard error can be used to construct confidence intervals and statistical tests and to plan the size of a sample survey that employs the sisterhood method. Statistical assumptions are discussed, particularly in relation to the effective sample size and to effects of extrabinomial variation. In a worked example of data from urban Pakistan, a maternal mortality ratio of 153 (95 percent confidence interval between 96 and 212) deaths per 100,000 live births is estimated.

PIP: The sisterhood method of calculating maternal mortality, which relies on surviving sisters to report on sibling mortality, is easy to use in the field and provides fast calculations of maternal mortality in settings with scarce data on vital statistics. This report describes a method of calculating sampling error for the sisterhood method. Calculation of sampling error allows investigators not only to report results with interval estimates but also to project sampling variability associated with various sizes of sample surveys in order to determine the most desirable sample size for estimation of maternal mortality rates. After explaining the statistical methodology, data from Karachi, Pakistan were applied to the model. Tables illustrate 1) the numbers of reported sister deaths in relation to maternal mortality rate, total fertility rate, and sample size for studies in nine countries and 2) the approximate sample sizes required to achieve the desired margin of error. The method to compute sample sizes necessary to enable a comparison of two maternal mortality rates based on sisterhood surveys is also presented, and the appropriateness of using the binomial formula is discussed. The problem of lag time in sisterhood surveys (where the time reference period may range from 5.7 to 15 years) is considered, and it is noted that use of the sisterhood method may be inappropriate in settings where maternal mortality has been changing rapidly. It is concluded that efforts should be made to reduce other potential sources of bias in retrospective, cross-sectional studies. The appendices contain the method to derive the standard error of an estimate of the maternal mortality rate and the method for calculating the total fertility rate and its sampling uncertainty.

Synthesis of the 123I- and 125I-labeled cholinergic nerve marker (-)-5-iodobenzovesamicol.

The highly toxic curraremimetic and cholinergic neuron marker (-)-5-iodobenzovesamicol (IBVM) has been labeled with iodine-125 and iodine-123. [125I]IBVM, suitable for animal distribution and ex vivo autoradiographic studies, was synthesized by solid-state exchange; isolated yields were 65-89% with specific activities in the range of 130-200 Ci/mmol. The synthesis of no-carrier-added (-)-5-[125I]IBVM from the corresponding chiral (-)-5-(tri-n-butyltin) derivative using Na125I was evaluated using the oxidants H2O2, peracetic acid and chloramine-T. Both peracetic acid and chloramine-T gave good yields (70-95%). However, when Na123I was utilized, acceptable yields of [123I]IBVM were obtained only with chloramine-T. Use of the latter oxidant did produce 5-chlorobenzovesamicol which was eliminated during HPLC purification. After optimization of the reaction parameters, [123I]IBVM in batch sizes of 10-27 mCi, is routinely obtained with a specific activity of 30-70,000 Ci/mmol, radiochemical purity (> 97%) and chiral purity (> 98%). Isolated radiochemical yields have averaged 71% (N = 40). Distribution analyses of [125I]IBVM and [123I]IBVM in mice 4 h following intravenous administration show essentially equivalent concentrations of the two tracers in the four brain regions sampled. The exceptionally high specific activity of [123I]IBVM has made possible the evaluation of this radiotracer in humans.

Hysteria and conversion in the ojibway patient: cross-cultural psychiatry for the family physician.

Case examples of hysterical coma and paralysis in two Ojibway patients are used to introduce a discussion of conversion symptoms. Somatoform disorders are described using the criteria of the Diagnostic and Statistical Manual of Mental Disorders, third edition; these are then applied to hysteria in the Native American patient. The authors discuss the cultural context of conversion symptoms in this population and describe guidelines for the provision of culturally sensitive therapy by the family physician.

Survival of bacterial isolates exposed to simulated Jovian trapped radiation belt electrons and solar wind protons.

With missions to Jupiter, the spacecraft will be exposed for extended durations to solar wind radiation and the Jovian trapped radiation belt. This study is designed to determine the effect of these radiation environments on spacecraft bacterial isolates. The information can be used in the probability of contamination analysis for these missions. A bacterial subpopulation from Mariner Mars 1971 spacecraft (nine spore-forming and three non-spore-forming isolates) plus two comparative organisms, Staphylococcus epidermidis ATCC 17917 and a strain of Bacillus subtilis var. niger, were exposed to 2, 12, and 25 MeV electrons at different doses with simultaneous exposure to a vacuum of 1.3 x 10(-4) N m-2 at 20 and -20 degrees C. The radioresistance of the subpopulation was dependent on the isolate, dose and energy of electrons. Temperature affected the radioresistance of only the spore-forming isolates. Survival data indicated that spores were reduced approximately 1 log/1500 J kg-1 (10 J kg-1=1 krad), while non-spore-forming isolates (micrococci) were reduced 1.5-2 logs/1500 J kg-1 with the exception of an apparent radioresistant isolate whose resistance approached that of the spores. The subpopulation was found to be less resistant to lower energy than to higher energy electrons. The bacterial isolates were exposed to 3 keV protons under the same conditions as the electrons with a total fluence of 1.5 x 10(13) p cm-2 and a dose rate of 8.6 x 10(9) p cm-2 s-1. The results showed that only 20% of S. epidermidis and 45% of B. subtilis populations survived exposure to the 3 keV protons, while the mean survival of the spacecraft subpopulation was 45% with a range from 31.8% (non-spore-former) to 64.8% (non-spore-former). No significant difference existed between spore-forming and non-spore-forming isolates.

Effect of ultraviolet on the survival of bacteria airborne in simulated Martian dust clouds.

A chamber was constructed to create simulated Martian dust storms and thereby study the survival of airborne micro-organisms while exposed to the rigors of the Martian environment, including ultraviolet irradiation. Representative types of sporeforming and non-sporeforming bacteria present in spacecraft assembly areas and indigenous to humans were studied. It was found that daily ultraviolet irradiation of 2 to 9 X 10(7) erg cm-2 was not sufficient to sterilize the dust clouds. The soil particles protected the organisms from ultraviolet irradiation since the numbers of survivors from irradiated environments were similar to those from unirradiated environments. Pending further data of the Martian environment, the contamination and dissemination of Mars with terrestrial micro-organisms is still a distinct possibility.

Use of the scanning electron microscope for viewing bacteria in soil.

Scanning electron microscopy was used for viewing Bacillus cereus and Staphylococcus aureus in three different soils. Both organisms were detected in the test soils at an approximate concentration of 10(7) cells per gram of soil; theoretically, the minimal number of microorganisms required for detection with the scanning electron microscope technique was between 10(7) and 10(10) cells per gram of soil. Because the concentration of cells was critical, the use of scanning electron microscopy as an extraterrestrial life detection instrument would be limited with soils containing more than 10(7) bacteria per gram of soil.

Survival of microorganisms in a simulated Martian environment. II. Moisture and oxygen requirements for germination of Bacillus cereus and Bacillus subtilis var. niger spores.

The effects of moisture and oxygen concentration on germination of Bacillus cereus and B. subtilis var. niger spores were investigated in a simulated Martian environment. Less moisture was required for germination than for vegetative growth of both organisms. A daily freeze-thaw cycle lowered moisture requirements for spore germination and vegetative growth of both organisms, as compared with a constant 35 C environment. Oxygen had a synergistic effect by lowing the moisture requirements for vegetative growth, and possibly germination, of both organisms. Oxygen was not required for spore germination of either organism, but was required for vegetative growth of B. subtilis and for sporulation of both organisms.

Survival and growth of potential microbial contaminants in severe environments.

Studies conducted in our laboratory have established that a number of potential soil microbes could survive a simulated Martian environment. In view of the uncertainty of the Martian environment and the importance of noncontamination of extraterrestrial bodies, studies were performed with common soil microbes to determine the minimal environment necessary to produce a complete growth cycle. The effects of diurnal temperature cycling (+25 degrees C to -65 degrees C) and of limiting concentrations of moisture and oxygen on spore germination, vegetative growth and sporulation of Bacillus cereus and B. subtilis have been determined. The results indicated that diurnally temperature-cycled heat-shocked spores of B. cereus in the simulated Martian atmosphere: 1) survived when the moisture concentration was < or = 4%; 2) germinated but became nonviable when the moisture concentration was > 4 < 8%; 3) germinated with subsequent vegetative growth when a) the moisture concentration was > or = 8%, and b) the concentration was > or = 6% and the partial pressure of oxygen was 15 mm; 4) sporulated when the moisture concentration was > or = 6% and the partial pressure of oxygen was 15 mm. Similar data for heat-shocked spores of B. subtilis in the simulated Martian atmosphere, diurnally temperature-cycled, indicated that the spores: 1) survived when the moisture concentration was > or = 6%; 2) germinated but became nonviable when the moisture concentration was > 1 < 4%; 3) germinated with subsequent vegetative growth when the moisture concentration was > or = 8%; 4) sporulated when the moisture concentration was > or = 6% and the partial pressure of oxygen was > or = 10 mm. Preliminary studies with B. cereus and B. subtilis spores produced in the simulated Martian environment and reintroduced into this environment indicated that vegetative cell growth and sporulation were normal. These data are discussed with regard to the probability of contamination of extraterrestrial bodies.