On the dynamics of populations with two age groups

By restricting the number of age groups to two and by introducing continued fractions, the dynamics of populations with deterministically changing vital rates are completely specified at all times. Explicit expressions for the sequence of the product of population projection matrices are given. From these, relative age distribution and reproductive values to any desired accuracy are obtained as functions of the vital rates. Thus, the results given in this paper are stronger than any existing weak ergodic theorems.

Declines in nonwhite and white neonatal mortality in Mississippi, 1975-80

Linked birth and death records provided the population for an investigation of declines in nonwhite and white neonatal mortality rates (NMR) in Mississippi between 1975 and 1980. The effect of changes in the characteristics of women giving birth and in perinatal care on declining NMRs was analyzed. A decomposition of the difference in the 1975-76 and 1979-80 NMRs was performed to determine whether declines in NMRs were due to shifts in population characteristics or in characteristic-specific rates. Between 1975 and 1980, the NMR declined significantly by 1 death per 1,000 live births per year among nonwhites and by 0.8 per 1,000 among whites. Increases in the number of prenatal visits during the study period were associated with part of this decline, especially for nonwhites. The effect of rising use of prenatal care on NMRs was not, however, a result of shifts in the birth weight distribution. The decrease in NMRs was also associated with declining birth weight-specific rates; 75 percent of the decrease in rates was noted among low birth weight infants. Shifts in the distribution of birth weight and in maternal characteristics had little effect on declining NMRs. A strong commitment of the Mississippi State Board of Health to provide prenatal care to indigent women may be responsible for the large increases in use of prenatal care among Mississippi women. The decline in NMRs among low birth weight infants is likely linked to greater availability of specialized care for the sick neonate, although survival of these infants increased across the State, even where specialized care was not available.

Oral contraception in Bangladesh

In rural Bangladesh, the continuation rate of oral contraceptives (OCs) is the lowest among all methods except for condoms, and the pregnancy rate for OC users is comparable to that for users of traditional methods, which lies halfway between that for foam and condom users (high) and Depo-Provera and IUD users (low). To determine why postpartum amenorrheic OC acceptors have shorter pregnancy intervals than postamenorrheic OC acceptors who were matched on time of acceptance as well as on age and parity, subintervals of the pregnancy interval are examined. Results reveal significantly shorter duration of use by amenorrheic acceptors. This short duration of use overrides their significantly longer duration to pregnancy since discontinuation, to give overall shorter duration to pregnancy since last birth.

Effects of physician counseling on the smoking behavior of asbestos-exposed workers

Physician antismoking advice has been shown to increase smoking cessation, particularly among patients who have medical problems or perceive themselves to be at risk. The present study tested three hypotheses: (a) providing 3 to 5 min of behavioral counseling regarding a cessation strategy would be more effective than simply warning the smoker to quit smoking; (b) smokers with abnormal pulmonary function would be more likely to comply with medical advice than would smokers with normal pulmonary function; and (c) that smokers with abnormal pulmonary function who receive behavioral counseling would be the group most likely to achieve prolonged abstinence. Asbestos-exposed smoking men undergoing screening in a mandated program for naval shipyard workers were categorized as having normal or abnormal pulmonary status on the basis of chest X ray and pulmonary function tests (PFT). They were then randomly assigned within PFT categories to receive either a simple warning or 3 to 5 min of behavioral cessation counseling from the physician who gave them the results of their pulmonary tests. Subjects' smoking status was evaluated at 3- and 11-month intervals following the physician intervention. Smokers who received behavioral counseling were more likely to quit and remain abstinent over the 11-month period (8.4% abstinent) than were smokers given a minimal warning (3.6% abstinent). Prolonged abstinence rates among abnormal PFT subjects (3.7%) did not differ from those of normals (5.9%). The group with normal PFT who received behavioral counseling achieved the highest level of abstinence (9.5%). Maintaining adequate physician compliance with the counseling protocol proved difficult; implications of this for future efforts are discussed.

Decomposition of the difference between two rates with hierarchical factors

A decomposition method for the difference between two rates when data are classified by two factors, one of which may be considered as a more direct factor than the other for the event under consideration, is presented in this paper. The two factors are treated as hierarchical and thus this method is conceptually different from the decomposition methods of Kitagawa (1955) and Das Gupta (1978), in which two factors are treated as symmetrical. Our method is shown to be a balanced version of the Cho-Retherford (1973) decomposition method. Analyses of neonatal mortality rates using our method are presented as an example.

Nuclear localization and phosphorylation of three 25-kilodalton rat stress proteins

The nuclear localization and phosphorylation of three 25-kilodalton rat myoblast stress proteins were examined. Data obtained in these analyses led to the following conclusions: (i) all three proteins become localized in the nucleus of stressed cells, (ii) two of the proteins are modified by phosphorylation, and (iii) phosphorylation occurs exclusively on serine residues.

Sources of prescription contraceptives and subsequent pregnancy among young women

For more than four in 10 teenage women who first obtained a prescription contraceptive from a private doctor or family planning clinic prior to pregnancy, marriage or interview in 1979, that method was the first they had ever used. Whites were over two times more likely to have previously used a nonprescription method than were blacks. Blacks, on the other hand, were two times more likely than whites to have been virgins before first using a prescription method. Slightly more than half of all young women who used a prescription method first obtained it from a family planning clinic, and the remainder got it from a private physician. Blacks were much more likely to have gone to a clinic than were whites. Nine in 10 of those who obtained a prescription method chose the pill. Among blacks, there was no appreciable difference between those who got the method from a clinic and those whose source was a private doctor. Whites who obtained their method from a private doctor, however, were somewhat more likely to choose the pill than were those who got it from a clinic. Of all who had been sexually active before ever using a prescription method, about eight out of 10 whites, but only about five in 10 blacks, had previously used a nonprescription method. Overall, there was an interval of about one year between first intercourse and the time the young women first got a prescription method. Among whites, there was no difference in parental education or family stability between clinic and private physician patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Phosphorylation pattern of a 25 Kdalton stress protein from rat myoblasts

Phosphorylation of a 25 Kdalton nuclear stress protein from rat muscle was examined by two-dimensional gel electrophoresis and one-dimensional peptide mapping. These studies show that three 25 Kdalton stress proteins found in stressed rat myoblasts are actually the same protein with charge variation brought about by multiple phosphorylations. Furthermore, the predominant charge variant of 25 Kdalton protein found in cells is dependent on the intensity of the stress applied to cells.

Behavioral, attitudinal, and physiologic characteristics of smoking and nonsmoking asbestos-exposed shipyard workers

The smoking characteristics of shipyard workers participating in an Asbestos Medical Surveillance Program (N = 3,991) were assessed. Sources of data were: (1) a self-assessment questionnaire on the smoking history and respiratory symptomatology of the 871 current smokers who participated in the smoking study, and (2) chest roentgenograms and pulmonary function test results and medical records for the entire population. The study population included 1,711 current smokers, 988 former smokers and 1,292 never smokers. The annual "quit rate" for former smokers had increased from less than 1% in 1961 to 4.2% in 1978. Of the 871 current smokers who participated in the smoking study, 19% had resumed smoking after having given up cigarettes for one year or longer. Men in the smoking study were reasonably well informed about the health consequences of smoking. While they perceived themselves to be susceptible to disease, and the disease to be serious, the benefits they saw in quitting were related more to economics and aesthetics than to health. When the results were age adjusted, no differences in rate of pulmonary function abnormalities and chest film abnormalities were found between current smokers who voluntarily participated in the smoking study and those who did not. All pulmonary function testing abnormality and chest film abnormality rates were significantly lower for former smokers and never smokers.

Arsenate induces stress proteins in cultured rat myoblasts

The induction of stress proteins was examined in rat myoblast cultures by two-dimensional gel electrophoresis. Data obtained by this analysis led to the following observations. (a) Arsenate, which behaves as a phosphate analogue in cellular phosphate-transfer reactions, stresses cultured rat cells and induces the synthesis of a unique set of proteins. (b) Most of the proteins synthesized after the addition of arsenate are identical to proteins synthesized in rat myoblasts in response to heat shock or arsenite stress. (c) However, both arsenic salts induce the synthesis of two unique proteins not induced by heat shock. (d) Five 25-30-kdalton stress proteins of rat cells do not contain methionine residues. (e) A majority of the proteins synthesized in stressed myogenic cells are also induced by stress in other rat cells such as hepatoma cells, pituitary tumor cells, and fibroblasts. The 25-30-kdalton stress-related proteins identified in myogenic cells, on the other hand, are induced in fibroblasts but not hepatoma or pituitary cells.

A protease is bound to rat liver nucleosomes

Nucleosome prepared from pure rat liver nuclei contain protease activity. No protease is associated with nucleosome core particle and the protease-containing nucleosome has considerably higher sedimentation coefficient than the bulk nucleosomes. Only H1 histone is susceptible to the nucleosome-bound protease.

The effect on fecundity of pill acceptance during postpartum amenorrhea in rural Bangladesh

The length of the interval from last live birth to the subsequent pregnancy was studied for 121 contraceptive pill acceptors who were in postpartum amenorrhea at the time of acceptance and 121 matched nonacceptors in a prospective study in Matlab, Bangladesh. Half of the pill acceptors discontinued use within seven months, and as a group the pill acceptors had a significantly shorter interval to the next pregnancy than the matched nonacceptors. These findings suggest that unless continuation rates can be improved, it is better not to encourage women in rural Bangladesh to start the contraceptive pill during postpartum amenorrhea.

Clonidine on the pressor response to raised intracranial pressure

We attemptedto clarify the mechanism of the pressor response to raised intracranial pressure (ICP) in urethane-anesthetized rabbits. Intraventricular clonidine inhibited the pressor response to raised ICP, and intraventricular phentolamine antagonized the inhibitory effect of clonidine on the pressor response. In reserpine-treated rabbits the pressor response to raised ICP was not observed. Following intraventricular norepinephrine, however, the pressor response was observed. Intraventricular clonidine inhibited the pressor response that could be observed in the reserpine-treated rabbits following the intraventricular norepinephrine. These results suggest that the central sympathetic neurons play an important role in producing the pressor response to raised ICP.

Synthesis of active site-directed organometallic irreversible protease inhibitors

p-Antimonybenzenesulfonyl fluoride and p-mercurybenzenesulfonyl fluoride irreversibly inhibit chymotrypsin (EC 3.4.21.1), trypsin (EC 3.4.21.4), and chromosomal protease, and these inhibitors appear to be as active as phenylmethanesulfonyl fluoride. The pretreatment of the proteases interferes with the phosphorylation of the active-site serine by diisopropylfluorophosphate suggesting that the organometallic inhibitors may also interact with the active site serine. The organometallic inhibitors may be used for localization of proteases in different parts of the cell by electron microscopy and p-mercurybenzenesulfonyl fluoride could also be used for isolation of proteases by sulfhydryl affinity chromatography.

Myopathy limited to the quadriceps and gastrocnemius muscles occurring in three brothers

This is a report of three cases of myopathy limited to the quadriceps and gastrocnemius muscles, occurring in the male offspring of the same mother but two different fathers. They have many similarities to a previously described clinical syndrome called quadriceps-confined myopathy. The pedigree demonstrates an apparent sex-linked recessive condition which has not been demonstrated previously. Information gained from a review of the literature is related to these three cases. It is suggested that these cases are part of a poorly defined clinical entity and that a new classification of quadriceps-gastrocnemius muscular dystrophy be introduced.

Partial exchange transfusion in sickle cell anemia. Use in children with serious complications

Seventeen children with sickle cell anemia received 40 partial exchange transfusions for serious complications of sickle cell anemia, and preoperatively to reduce the risk of anesthesia. Each patient received two partial exchange transfusions at 24-hour intervals and all patients tolerated the exchange transfusions well. The mean hematocrit level rose from 22.9% before the exchange transfusion to 40.6% at the end of the second exchange. The mean sickle hemoglobin level decreased from 93.8% before the exchange to 28.0% after the second exchange. Patients with acute lung syndrome had remarkable improvement in clinical symptoms and PaO2 levels, and those with acute liver crisis had substantial reduction in serum bilirubin levels. All the other patients showed marked clinical improvement following the exchange transfusions.

Dynamics of some special populations with NRR = 1

We discuss two special cases of population dynamics with changing vital rates subject to the constraint NRR = 1 and consider the specifics of ergodicity and stationarity. By restricting the number of age groups to two, we can make explicit the way weak ergodicity works. When mortality is constant and the period NRR = 1, a life-table stationary population eventually results; everything of demographic interest (except age-specific fertility and the cohort NRR) is asymptotically constant. With changing mortality, but both period and cohort NRR = 1, only weak ergodicity holds, and everything changes over time.

Genetic variation in irradiated and control populations of Cnemidophorus tigris (sauria, teiidae) from Mercury, Nevada with a discussion of genetic variability in lizards

Whiptail lizards (Cnemidophoms tigris) were collected from fenced irradiated, fenced control, and unfenced areas near Mercury Nevada. No changes in allele frequencies at 26 allozyme loci could be ascribed to irradiation or fencing. This species is the most polymorphic and heterozygous lizard so far examined. - Heterozygosity estimates derived from electrophoretic studies on 20 additional species of lizards are compared with Cnemidophorus. A general trend seems to emerge. Fossorial lizards have uniformly low levels of heterozygosity (ca. 1 %). Territorial "sit and wait" predators are intermediate (ca. 5%). Highly vagile apparently nonterritorial lizards are the most heterozygous (ca. 10%). Assuming that this trend does not reflect some of sampling error, two current, non-mutually exclusive hypotheses explain the observed situation: (1) the niche width variation hypothesis predicts, higher variability in populations where individuals are exposed to largescale environmental heterogeneity; and (2) the population size hypothesis predicts that, all other things being equal, vagility would tend to increase the effective population size by reducing inbreeding, which would promote higher levels of genetic variation.