Respiratory distress syndrome in second-born versus first-born twins. A matched case-control analysis

The well-known increased risk of the respiratory distress syndrome in a twin born second as compared with the twin born first is usually attributed to the second twin's predisposition to depression at birth ("asphyxia"). We analyzed the etiologic roles of birth order, presentation, and depression at birth in the development of the respiratory distress syndrome in matched case-control populations drawn from 221 preterm twin pairs. Among the 39 twin pairs discordant for respiratory distress syndrome, the second twin was the affected member in 31 pairs. Second birth order was the only independent risk factor, but only in vaginal deliveries (matched odds ratio, 14.2; 95 percent confidence interval, 2.5 to 81.1). Second twins delivered abdominally did not have an increased risk relative to first twins (odds ratio, 0.9; confidence interval, 0 to 17.8). When depression at birth was evaluated as an outcome variable, malpresentation, rather than birth order, was the major risk factor (independent matched odds ratios of 2.7 [confidence interval, 1.0 to 7.5] and 1.3 [0.7 to 2.5], respectively). Thus, second twins' increased risk of respiratory distress syndrome cannot be explained by a predisposition to depression at birth; a more important factor may be that second twins do not benefit from the salutary effects of labor to the same extent as first twins.     

Induction of protective immunity to monoclonal-antibody-defined Plasmodium falciparum antigens requires strong adjuvant in Aotus monkeys.

Monoclonal antibodies to the major Plasmodium falciparum merozoite surface coat and rhoptry antigens were produced. A combination of the affinity-purified polypeptides with Freund complete adjuvant which was given three times completely protected an Aotus lemurinus azure (karotype VI) monkey against homologous challenge; however, immunization with the same polypeptides with a muramyl dipeptide derivative [MDP-Lys(L18)] did not protect a second Aotus monkey, even though comparable high antibody titers were induced.     

The increased needs of patients in nursing homes and patients receiving home health care

To evaluate the effects of Medicare's prospective payment system and Medicaid's preadmission regulations on long-term care, we constructed clinical profiles in 1982 and 1986 of about 500 randomly selected patients from each of three types of facilities: nursing homes with relatively high proportions of Medicare patients (high-Medicare nursing homes; n = 23), traditional nursing homes (n = 19), and home health agencies (n = 18). Data were obtained directly from the care givers on the medical problems, problems requiring skilled nursing, and functional problems of these representative patients from 12 states. For Medicare patients in high-Medicare nursing homes, the prevalence of medical problems and problems requiring skilled nursing increased substantially, whereas the prevalence of functional problems remained relatively unchanged. For example, from 1982 to 1986 there was a marked increase in the frequency of tube feedings (21 to 29 percent), oxygen use (6 to 14 percent), urinary tract infection (7 to 13 percent), and diastolic hypertension (1 to 10 percent), but not difficulty in eating (48 to 51 percent) or speaking (28 to 29 percent). In contrast, in traditional nursing homes there was an increase in the prevalence of functional disability, but virtually no change in that of problems requiring medical and skilled nursing care. In home health care the functional care needs of Medicare patients increased significantly, and there was a slight increase in the prevalence of problems requiring medical and skilled nursing care. We conclude that from 1982 to 1986 the needs of patients in long-term care increased substantially. This trend appears to result from Medicare's prospective payment system, which encourages earlier hospital discharge to long-term care settings, and from Medicaid's policy of de-institutionalization. Meeting this greater need for care will be costly. We require a better system of reimbursing for long-term care and ensuring its quality.     

Cystic fibrosis: Synthesis of ciliary inhibitor by amniotic cells

The presence of a ciliary inhibitor in media of cultured amniotic cells obtained from a fetus heterozygous for cystic fibrosis has been observed by the oyster gill cilia assay. The chromatographic fraction containing the inhibitor corresponded to eluted fractions chromatographed from cystic fibrosis fibroblast media and serum. An analogous chromatographic fraction from media of cultured amniotic cells from two proportedly normal fetuses did not inhibit cilia. The chromatographic fraction from media of cultured amniotic cells of a fetus at high risk for cystic fibrosis did not inhibit ciliary activity. Serum was collected from this baby seven weeks after birth and also did not inhibit ciliary action, indicating a homozygous normal genotype. These observations may lead to the development of an antenatal test for cystic fibrosis.     

An octosporeosis of the black blowfly,Phormia regina: Incidence rates of host and parasite

Summary Adult black blowflies Phormia regina were trapped from April through October in Urbana, Illinois for the years 1963 and 1964. Samples of flies from each catch were examined for the presence of the microsporidian parasite Octosporea muscaedomesticae. In 1963, the monthly parasite incidence rate steadily increased with the progression of the seasons while the fly population declined over the same period. In 1964, the monthly parasite incidence rate followed no decernable pattern; this was probably attributable to the fact that the host remained comparatively scarce for the entire period following heavy spring rains. The observed monthly parasite incidence rates ranged from zero to 13% over the two-year period. The annual parasite incidence rate was 4% in 1963 and 4.5% in 1964. No significant differences were found in the parasite incidence rates of females versus males. The observed parasite incidence rates, while indicative of general trends, probably are lower than the actual rates in nature. Reasons for this are discussed. Finally it is suggested that O. muscaedomesticae may at times act as a suppressor of P. regina populations in the field.

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Zusammenfassung Erwachsene Fliegen der Art Phormia regina wurden vom April bis Oktober in Urbana, Illinois, in den Jahren 1963 und 1964 gefangen. Einige Fliegen aus jedem Fang wurden auf Microsporidien der Art Octosporea muscaedomesticae untersucht. Im Jahre 1963 erhöhte sich die monatliche Infektionsrate ständig mit dem Fortschreiten des Jahres, während sich die Fliegenpopulation in derselben Periode verminderte. Im Jahre 1964 war eine solche Beziehung nicht erkennbar; dieser Umstand wird darauf zurückgeführt, daß der Wirt während der ganzen folgenden Periode der schweren Frühlingsregenfälle relativ spärlich auftrat. Die beobachtete monatliche Parasitenhäufigkeit wechselte während der 2-Jahresperiode zwischen 0 und 13%. Die jährliche Parasitenhäufigkeit lag 1963 bei 4% und im Jahre 1964 bei 4,5%. Es war keine significante Differenz in der Parasitenhäufigkeit zwischen weiblichen und männlichen Tieren festzustellen. Die beobachtete Parasitenhäufigkeit war, wenn man den generellen Trend betrachtet, wahrscheinlich eher geringer als die aktuelle Rate in der freien Natur. Die Gründe für diese Umstände werden diskutiert. Schließlich wird angenommen, daß sich O. muscaedomesticae als ein begrenzender Faktor (supressor) für P. regina Population in der freien Natur anzusehen ist.

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This study was supported in part by Research Grant AI-05068 from the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, U.S. Public Health Service.     

Effects of learned helplessness on brain GABA receptors

GABA is involved in both clinical depression and in animal models of depression; however, the roles of GABA(A) and GABA(B) receptors in specific brain regions are not clear. Changes in densities of both GABA(A) and GABA(B) receptors have been reported with the learned helplessness animal model of depression and with chronic antidepressant drug treatment. However, some of these findings are discrepant. Thus, we used quantitative autoradiography to study the GABA(A) and GABA(B) receptors in learned helplessness and we used an experimental paradigm that allows non-specific effects of stress to be differentiated from learned helplessness. Densities of GABA binding were measured in prefrontal cortex, septum, hippocampus, hypothalamus and amygdala. In the septum, learned helpless rats had increased densities of GABA(A) receptors and rats that did not become helpless after inescapable stress had decreased GABA(B) receptor densities. No significant group differences of GABA(A) or GABA(B) receptor densities were observed in any other brain region studied. These results suggest a unique role for the septum in modulating GABA in the learned helplessness animal model of depression.     

Age effects on executive ability

Heterogeneity of executive tasks has made it difficult to determine whether there are age-related declines in executive functioning. To address this issue, 112 individuals, 20-79 years old, took the California Trail Making Test (CTMT) and the California Stroop Test (CST), subtests of the Delis-Kaplan Executive Function Scale (D. C. Delis, E. Kaplan, & J. H. Kramer, in press) that include measurement of component skills embedded in the executive function tasks. Multiple regression analyses revealed that after controlling for component skills, age had a significant effect on the executive requirement of the CST, namely speed on the interference condition. Age did not affect switching performance on the letter-number condition of the CTMT. Additional analyses revealed that age was significantly associated with commission of certain types of errors. This study confirms the importance of partialing out components in the assessment of multidimensional cognitive tasks, particularly when making age comparisons. It also emphasizes specificity over generalizability when examining the impact of age on cognition.