Interaction of somatomedin-C with an antibody directed against the synthetic C-peptide region of insulin-like growth factor-I.

Insulin-like growth factor-I is a human plasma peptide with strong structural homology to human prosinsulin. This peptide has been classified as a somatomedin on the basis of its biological actions and growth hormone dependence. We have generated an antibody to the synthetic 12 amino acid C-peptide region of insulin-like growth factor-I and used it to compare three somatomedin preparations to insulin-like growth factor-I. We also compared these somatomedin preparations to insulin-like growth factor-I using the standard SM-C RIA. We conclude that insulin-like growth factor-I and somatomedin-C behave identically in these two RIA's and are very similar if not identical molecules.

Influences on the antenatal clinic attendance of Central Province women in Port Moresby, PNG.

Public antenatal health care services in the National Capital District (NCD) of Papua New Guinea are provided at some of the nurse operated urban satellite clinics and at a large outpatient clinic at Port Moresby General Hospital (PMGH). The major functions of the antenatal clinics are screening for high risk cases and giving routine medications. In this they are following the policy of the National Health Plan and the recommendations of the Public Health Department reports on which it was partially based. The purpose of this study was to examine some of the characteristics of a particular segment of the clientele at the PMGH antenatal clinic and to explore their motivation for attendance, especially the timing of their first visit. After an initial survey of the clinic record cards of all women attending the PMGH clinic in September 1980, interviews were conducted with a stratified sample of women attending clinic sometime between February and June 1981. Only women indigenous to the NCD and the surrounding province were included in the study. From clinic record cards, information was obtained on each woman's residence, birthplace, parity, gestational stage at first clinic visit, place of previous deliveries, clinical/laboratory measures and obstetric history. The interviews were conducted in a private room near the clinic in a language preferred by the interviewee. Their responses clarified some of the background data on their clinic cards and provided additional information on why they came to the clinic when they did. In general, the sample group was highly oriented toward Western-based medical care. They came to have themselves and their babies examined for possible problems, to receive the right amounts of the right medicines, and to get information. This was consistent with both policy and services. They also came because of the perceived effectiveness of the clinic and sometimes because it was the 'proper thing to do'. Many factors influenced their choice of when and where to seek antenatal services, including advice from husbands as well as from traditional female sources. Their previous experiences with hospitals and clinics and with pregnancy in general were also important.

Characteristics of a multidipole ion source.

The properties of a steady-state, dc discharge multidipole ion source have been investigated. The plasma density in the source depends on the magnet geometries, the discharge voltage, and the bias voltage on the first extraction grid. Different schemes to reduce the loss of ions to the chamber wall are described. Hydrogen ion species in the extracted beam are studied by a mass analyzer.

Infant feeding practices among clinical nursing staff in urban Papua New Guinea.

PIP: To determine the personal attitudes of urban public nursing staff toward infant feeding practices, 97 nurses and aides who were mothers and also full-time staff at public health care facilities in Port Moresby were interviewed in 1981. In 1977, Papua New Guinea passed legislation making infant feeding bottles and teats available only through prescription by an authorized health professional. This legislation was supplemented by an educational campaign advocating breastfeeding. The nursing staff is important to this campaign, since those charged with administrative duties can prescribe bottles; moreover, as a result of their close contact with patients, nursing staff influence mothers' attitudes toward infant feeding. The nurses and aides interviewed ranged in age from 21-50 years; 75 had at least 1 child under age 5. Each child was classified as breastfed, mixed-fed (use of supplementary bottle 1 or more times a week), or bottlefed. 185 (71%) of the 260 babies included in the study were exclusively breastfed, while 72 (28%) received milk from both breast and bottle. No significant difference in feeding practices occurred after the 1977 legislation. Attitudes were strongly in favor of breastfeeding, with bottle feeding considered appropriate only under highly specific conditions. There was a significant difference (p0.001) between children of mothers who returned to work within the 1st 6 months postpartum and those of mothers who returned later in the proportion that were bottlefed at least occasionally. More detailed information was elicited on the mothers' youngest child. The mean age of weaning from the breast among the 44 youngest children who were under age 5 1/2 at the time of the interview was 21 months. The mean age for bottle introduction and bottle termination was 2 months and 12 months, respectively. 67 (80%) of mothers in this group returned to work within the 1st 3 months postpartum; however, 41 continued to exclusively breastfeed. This was possible because a creche was provided at the job, or the place of work was close enough for the childminder to bring the infant to the mother for feeding at the 2 1/2 hour breaks provided to all wage-employed mothers. This survey suggests that promotion of breastfeeding must be complemented by the provision of adequate opportunities in the work place for infant feeding.^ieng

Antenatal health care policy, services and clients in urban Papua New Guinea.

PIP: This article describes the nurse-operated antenatal clinic services in Port Moresby, Papua New Guinea, and reports the findings of a survey of 365 women attending the Port Moresby General Hospital antenatal clinic. Only 9% of the women surveyed attended the clinic in the 1st trimester of their pregnancy, with the majority making their 1st visit toward the end of the 2nd trimester. There was a trend toward later 1st visits with higher parities. 74% of previous deliveries had been in a hospital. Low hemoglobin level (52% under 10 gm%) was the common risk factor noted in the sample. The number of attendees generally decreased with increasing distance between home and hospital. To explore the factors associated with clinic attendance, a subsample of 48 women were interviewed in depth. Clinic attendance was found to be significantly associated with the experience of current or previous obstetrical problems. The need to discover problems, obtain medication, and gain knowledge were reasons cited for clinic attendance. Respondents indicated they selected the hospital clinic because they expected greater expertise or better services. Clinic attendance was in some cases adversely affected by personal embarrassment stemming from questions about marital status from staff. Approximately 75% of women in the sample came from heterogeneous suburban areas that lack the social support systems commonly provided by extended family groupings. It is suggested that nursing interventions, based on comprehensive counseling as well as a caring approach, can play a unique role in the professional support system for obstetric care. It is important for nurses who function in antenatal clinic settings serving clients of diverse ethnicity to be aware of the cultural beliefs and values that influence health care perceptions and practices. Although nurses perform the majority of antenatal care in Papua New Guinea, their knowledge of high risk factors is weak. Use of a specialized antenatal clinic card, as well as continuing education, are recommended to sharpen nurses' assessment skills and facilitate early detection of high risk clients.^ieng

Substance use in pregnancy among two groups of urban women in Papua New Guinea.

Although use of common psychoactive drugs during pregnancy may have deleterious effects on the fetus, little is known about patterns of use of these substances among Third World women of childbearing age. Interview data are presented from two different groups of young women resident in the national capital of Papua New Guinea in 1980-1981 regarding use of alcoholic beverages, cigarettes, caffeinated beverages and betel, and their opinions on the appropriateness of such practices during pregnancy. Approval of use during pregnancy reflected reported consumption: caffeine was most acceptable, cigarettes were least. Patterns of cigarette use reported here may threaten pregnancy outcome.

Breasts, bottles and babies: historical changes in infant feeding practices in a Micronesian village.

PIP: In an effort to study changes in modes of infant feeding over time, the mothers of 375 children born in a Micronesian village during the past 50 years were interviewed regarding their infant feeding practices. The 83 women residents in Peniyesene village in March 1976, who had borne children while residing on Moen Island, were interviewed in their homes. During the 1945-1975 period, use of commercial formula increased steadily, while breastfeeding declined, age at weaning from breast decreased, and consumption of milk by 1-2 year-olds increased. In the 1970s these trends accelerated. Prior to 1940 the use of powdered or evaporated milk was introduced into the Truk District. Educational level and employment history of the mother were significantly associated with bottlefeeding. Convenience was the most commonly reported reason for bottlefeeding. The course of infant feeding practices in the village appeared to have been affected by historical factors which are reviewed.^ieng

Infant feeding and infant illness in a Micronesian village.

PIP: The 49 infants born over a 2-year period in a single community in Truk, Micronesia, were studied in 1976 in order to determine the influence of current infant feeding practices on infant morbidity. Only 9 of the 49 infants were exclusively breastfed in their first year of life, and 20 were weaned completely from breast to bottle during their first 6 months. Very few mothers intended to breastfeed after the second year. 40 of the 49 babies received semisolid foods in the first 6 months. By early in the second year most children were eating normal adult diets. Most mothers were familiar with the procedures of proper bottle and formula care, but poor sanitary conditions, lack of refrigeration and inadequate supervision of older siblings made proper care difficult. Hospital records and parental reports indicate that almost all children in the sample experienced minor ailments at least occasionally in their first year. Although the sample size is too small for tests of significance, it is apparent that a much higher proportion of infants were seriously ill when exclusively bottle fed than when exclusively breast fed. All the children hospitalized within 8 weeks of birth had experienced either supplementary or complete bottlefeeding.^ieng

Prefrontal control of conditioned suppression and associated cardiovascular variables in the monkey (Macaca mulatta).

Rhesus monkeys were trained in a discriminated conditioned emotional responses paradigm. The discriminated conditioned response (CR) complex consisted of bar-press suppression, increased terminal aortic blood flow, and increased arterial pressure. Bar-press suppression and blood flow responses were temporarily eliminated by single-stage bilateral prefrontal lobectomy but not by extensive posterior cortical ablation, 2-stage prefrontal lobe removal, or 3-stage prefrontal cortical surface ablation. The blood pressure CR was attenuated by almost every surgical operation. The changes in heart rate paralleled changes in general activity. These data indicate that the prefrontal lobes influence the conditioned suppression of ongoing rewarded behavior and the vascular responses accompanying the suppression. The time course for recovery of the somatic CR after lobectomy differed from those of the cardiovascular CRs.

Education of women and family size in 2 Micronesian communities.

PIP: Household census and village records for 255 women aged 15 to 64 who were living in Truk, Micronesia, are analyzed for marital history, number of children, educational status, and current employment. Marital fertility is found to be lower among those with higher education and those currently employed. Comparisons are made with the situation in other countries.^ieng

Identification of alpha 2-macroglobulin conformational intermediates by electron microscopy and image analysis. Comparison of alpha 2-macroglobulin-thrombin and alpha 2-macroglobulin reacted with cis-dichlorodiammineplatinum(II) and trypsin.

Human alpha 2-macroglobulin (alpha 2M) exists in two well defined, highly distinct conformations and in less well described intermediate conformations. In this study, previously characterized reactions were used to partially or completely transform the conformation of alpha 2M. Electron micrographs of each preparation were subjected to image analysis. Ternary alpha 2M-trypsin (2 mol of trypsin/mol of alpha 2M) was analyzed as a control for the fully transformed state. Correspondence analysis (CORAN) and hierarchical ascendant classification (HAC) generated five image clusters from 330 aligned alpha 2M-trypsin complexes. Average images of each cluster resembled the letter "H" with four nearly equivalent lateral arms. Abnormally shaped lateral arms were not demonstrated by HAC, using a variety of factor sets. In a native polyacrylamide gel electrophoresis system, alpha 2M-thrombin migrated in a diffuse band partially behind alpha 2M-trypsin, suggesting conformational heterogeneity. CORAN and HAC of 733 alpha 2M-thrombin complexes identified two neighboring clusters, the average images of which showed an H-like structure in which one arm was replaced by a globular stain-excluding body. The two alpha 2M-thrombin clusters included 125 images (17.1% of image population). The complete absence of atypical lateral arm structure in the alpha 2M-trypsin clusters suggests that this variation is not the result of orientation or staining artifact. Native alpha 2M was reacted with cis-dichlorodiammineplatinum(II) and then with trypsin to form alpha 2M-Pt-trypsin, a preparation that includes partially transformed alpha 2M structures. CORAN and HAC of 580 alpha 2M-Pt-trypsin complexes generated five clusters, the average images of which showed atypical lateral arm structure equivalent to that demonstrated with alpha 2M-thrombin. The five alpha 2M-Pt-trypsin clusters accounted for 15.2% of the image population. These studies suggest that alpha 2M conformational change intermediates demonstrate common structural characteristics, permitting an elucidation of the steps involved in this complex transformation.

Binding of transforming growth factor-beta 1 to methylamine-modified alpha 2-macroglobulin and to binary and ternary alpha 2-macroglobulin-proteinase complexes.

The binding of 125I-labelled transforming growth factor-beta 1 (TGF-beta 1) to human alpha 2-macroglobulin (alpha 2M) was studied by native PAGE and autoradiography. TGF-beta 1 bound preferentially to alpha 2M-methylamine and minimally, if at all, to native alpha 2M. Preparations of alpha 2M-proteinase complex were generated by incubating a standard concentration of alpha 2M (0.4 microM) with different concentrations of trypsin, chymotrypsin or neutrophil elastase (0.04-2.0 microM). The 125I-TGF-beta 1-binding activity depended on the initial ratio of active proteinase to alpha 2M, or r value, used to form the alpha 2M-proteinase complex. With all three proteinases, r values of 2 or greater yielded preparations with unchanged or decreased TGF-beta 1-binding activity relative to native alpha 2M. By contrast, r values near 1 yielded preparations with significantly increased TGF-beta 1-binding activity. The results of [3H]thymidine-incorporation studies performed in mouse keratinocytes were consistent with the 125I-TGF-beta-binding experiments. alpha 2M-trypsin and alpha 2M-chymotrypsin prepared at an r value of 1.0 counteracted the activity of TGF-beta 1, whereas the equivalent complexes prepared at an r value of 3.0 had no effect. As determined by SDS/PAGE, 125I-TGF-beta 1 binding to alpha 2M-methylamine was at least 80% non-covalent. Reaction of alpha 2M-methylamine with iodoacetamide or 5,5'-dithiobis-(2-nitrobenzoic acid) decreased the percentage of covalent binding but had no effect on total binding. Neuraminidase treatment had no effect on the binding of 125I-TGF-beta 1 to alpha 2M-methylamine. Cleavage of the 'bait regions' in alpha 2M-methylamine by prolonged treatment with trypsin also had no effect. These studies suggest that TGF-beta 1 binding to alpha 2M is enhanced by conformational change in the proteinase inhibitor resulting from reaction with proteinase or amine. If both proteinase-binding sites in a single alpha 2M molecule are occupied, TGF-beta 1-binding activity is decreased or perhaps eliminated.

Electron microscopy studies of alpha 2-macroglobulin subunit association after limited reduction with dithiothreitol.

The subunits of human alpha 2-macroglobulin (alpha 2M) were dissociated by treatment with reductant (0.5 mM dithiothreitol) under mild conditions. Intact tetramers, half-molecules (subunit dimers), and monomers were identified by chromatography on Superose-6. These products were not in rapidly reversible equilibrium since purified half-molecules were completely stable for up to 18 h. Monomers slowly associated to form some half-molecules in the same time period. Negatively stained preparations of monomers and half-molecules demonstrated significant heterogeneity by electron microscopy. This heterogeneity probably reflected structural differences as well as variation in projection and staining. After reaction with methylamine or proteinase, half-molecules and purified monomers reassociated. The principal product was an intact tetramer displaying an "H-like" image which was visually indistinguishable from the structure of intact tetrameric alpha 2M after conformational change. Incompletely reassociated alpha 2M species were also identified after performing chromatography to increase the fraction of these products. Images resembling one-half of the intact tetrameric alpha 2M structure (epsilon-image) or three-quarters of the intact tetramer (chair-image) were observed. These studies demonstrate that reassociation of reductant-dissociated alpha 2M subunits occurs by the formation of appropriate interactions, so that the resulting tetramers are equivalent to nontreated alpha 2M-trypsin. Unlike native alpha 2M, the structure of conformationally transformed alpha 2M is relatively insensitive to the loss of interchain disulfide bonds. We propose that reassembly of alpha 2M subunits occurs by the binding of two half-molecules or by the addition of individual subunits to half-molecules or trimers.