Showing papers by "University of Miami published in 1988"

Idiopathic senile macular hole. Its early stages and pathogenesis.

Abstract: Evidence is presented that idiopathic senile macular hole is caused by focal shrinkage of the vitreous cortex in the foveal area. The most reliable biomicroscopic signs of impending hole formation (stage 1) are the development of a yellow spot or ring in the center of the fovea, loss of the foveal depression, and no evidence of separation of the vitreous from the foveal retina. Although in a majority of eyes with stage 1 changes there is a progression to hole formation, spontaneous separation of the vitreous without hole formation may occur in some cases (44%) and cause characteristic biomicroscopic changes, including foveal reattachment, disappearance of the yellow spot or ring, and, in some cases, a pseudo-operculum, with one or more lamellar holes or facets. A prospective collaborative study is recommended to confirm these findings and to test the clinical value of surgical peeling of the vitreous cortex in eyes with stage 1 changes as a means of preventing hole formation.

Effect of Ischemia on the In Vivo Release of Striatal Dopamine, Glutamate, and γ-Aminobutyric Acid Studied by Intracerebral Microdialysis

Abstract: We have previously described a marked attenuation of postischemic striatal neuronal death by prior substantia nigra (SN) lesioning. The present study was carried out to evaluate whether the protective effect of the lesion involves changes in the degree of local cerebral blood flow (ICBF) reduction, energy metabolite depletion, or alterations in the extracellular release of striatal dopamine (DA), glutamate (Glu), or gamma-aminobutyric acid (GABA). Control and SN-lesioned rats were subjected to 20 min of forebrain ischemia by four-vessel occlusion combined with systemic hypotension. Levels of ICBF, as measured by the autoradiographic method, and energy metabolites were uniformly reduced in both the ipsi- and contralateral striata at the end of the ischemic period, a finding implying that the lesion did not affect the severity of the ischemic insult itself. Extracellular neurotransmitter levels were measured by microdialysis; the perfusate was collected before, during, and after ischemia. An approximately 500-fold increase in DA content, a 7-fold increase in Glu content, and a 5-fold increase in GABA content were observed during ischemia in nonlesioned animals. These levels gradually returned to baseline by 30 min of reperfusion. In SN-lesioned rats, the release of DA was completely prevented, the release of GABA was not affected, and the release of Glu was partially attenuated. However, excessive extracellular Glu concentrations were still attained, which are potentially toxic. This, taken together with the previous neuropathological findings, suggests that excessive release of DA is important for the development of ischemic cell damage in the striatum.

Key features of heat shock regulatory elements.

Abstract: The promoters of heat shock protein genes are among the best-studied inducible eucaryotic promoters. Regions responsible for heat regulation have been identified previously by deletion experiments with several different heat shock genes. In this paper the critical importance of two novel features of heat shock regulatory elements was investigated. First, the elements were modular and, as a consequence, displayed a characteristic 5-nucleotide periodicity produced by multiple GAA blocks that were arranged in alternating orientations and at 2-nucleotide intervals. Functional heat shock regulatory elements appeared to include three or more of these blocks. Second, the nucleotides at the two positions immediately upstream from GAA segments played an important role in defining the competence of regulatory elements.

Child-care costs and family labor supply.

Abstract: This paper presents a theoretical and empirical analysis of the effects of child care costs on family labor supply and the demand for market child care The model is a framework for cross-section estimation of the effects of child care costs on labor supply and child care use It applies to households having young children requiring continuous care and in which both the mother and 1 other potential child care provider are present The 3 potential sources of child care are the mother the potential informal provider and the market Using data from the 1980 baseline household survey of the Employment Opportunity Pilot Projects this empirical analysis uses a subsample of 6170 households in which there is a married woman under age 45 with her spouse present at the time of the survey at least 1 child under age 14 and nonmissing data on key variables Results show that 1) higher market child care costs discourage women from working even when an informal source of care is available indicating that such informal care is an imperfect substitute for market care; 2) a higher wage rate for the mother encourages her to work thus a higher wage rate increases the probability of using market child care; 3) the number of children requiring care has a negative impact on the probability of the women working with the largest impact caused by younger children; 4) nonwage income has a negative impact on the probability of the woman working; and 5) black women are more likely to work than whites and are statistically more likely than whites to use market child care if they do work This family labor supply model predicts that the cost of market child care will affect household decisions on labor supply and child care use Estimates of a qualitative choice model provide strong confirmation that child care costs affect such decisions The responsiveness of the labor supply of mothers to child care costs demonstrated in this study indicate that such subsidies do have their intended effect of encouraging labor supply The fact that a large proportion of current child care subsidies benefit primarily middle and upper income families via the income tax credit suggests that the labor supply effets of such subsidies may in practice be stronger for less needy families than for low income families Employer-subsidized child care may become an increasingly popular tool for attracting mothers into the labor force

Infants of depressed mothers show "depressed" behavior even with nondepressed adults.

Abstract: To determine whether the "depressed" behavior (e.g., less positive affect and lower activity level) of infants noted during interactions with their "depressed" mothers generalizes to their interactions with nondepressed adults, 74 3-6-month-old infants of "depressed" and nondepressed mothers were videotaped in face-to-face interactions with their mothers and with nondepressed female strangers. "Depressed" mothers and their infants received lower ratings on all behaviors than nondepressed mothers and infants. Although the infants of "depressed" versus nondepressed mothers also received lower ratings with the stranger adult, very few differences were noted between those infants' ratings when interacting with their mother versus the stranger, suggesting that their "depressed" style of interacting is not specific to their interactions with depressed mothers but generalizes to their interactions with nondepressed adults as early as 3 months of age.

The role of audition in infant babbling.

Abstract: The traditional belief that audition plays only a minor role in infant vocal development depends upon evidence that deaf infants produce the same kinds of babbling sounds as hearing infants. Evidence in support of this position has been very limited. A more extensive comparison of vocal development in deaf and hearing infants indicates that the traditional belief is in error. Well-formed syllable production is established in the first 10 months of life by hearing infants but not by deaf infants, indicating that audition plays an important role in vocal development. The difference between babbling in the deaf and hearing is apparent if infant vocal sounds are observed from a metaphonological perspective, a view that takes account of the articulatory/acoustic patterns of speech sounds in all mature spoken languages.

5 Vitellogenesis and Oocyte Assembly

Abstract: Publisher Summary This chapter describes the different aspects of vitellogenesis and oocyte assembly The major components of fish oocytes are derived from the blood-borne high-molecular-weight compound, vitellogenin, which is synthesized in the liver of oviparous vertebrates The classification of vitellogenin as a phospholipoglycoprotein indicates the crucial functional groups that are carried on the protein backbone of the molecule—namely, lipids, some carbohydrates, and phosphate groups In the rainbow trout, estrone administration leads to the induction of vitellogenin synthesis in the liver and its release into the bloodstream, but estrone displays only 5%–12% of the potency of estradiol The biochemical information concerning vitellogenin clearly indicates that a great deal of posttranslational modification must occur in the liver cell to reach the finished product seen in the serum An integral part of estradiol action is the observed hypercalcemia in vitellogenic fish, which can largely be ascribed to the calcium-binding properties of phosphorylated and highly charged, components of the native vitellogenin molecule

Extensive variation of human immunodeficiency virus type-1 in vivo.

Abstract: Genotypic variation among independent isolates of human immunodeficiency virus type-1 (HIV-1) is well known, but its molecular basis and biological consequences are poorly understood. We examined the genesis of molecular variation in HIV-1 by sequential virus isolations from two chronically infected individuals and analysis of recombinant HIV-1 genomic clones. In three different virus isolates full-length HIV-1 clones were identified and found to consist, respectively, of 17, 9 and 13 distinguishable, but highly-related, viral genotypes. Thirty-five viral clones derived from two HIV-1 isolates obtained from the same individual but 16 months apart showed progressive change, yet were clearly related. Similar changes in the HIV-1 genome did not occur in vitro during virus isolation and amplification. The results indicate that HIV-1 variation in vivo is rapid, that a remarkably large number of related but distinguishable genotypic variants evolve in parallel and coexist during chronic infection, and that 'isolates' of HIV-1, unless molecularly or biologically cloned, generally consist of complex mixtures of genotypically distinguishable viruses.

Peer Interaction and Problem Solving: When Are Two Heads Better Than One?.

Abstract: AZMITIA, MARGARITA. Peer Interaction and Problem Solving: When Are Two Heads Better Than One? CHILD DEVELOPMENT, 1988, 59, 87-96. 80 5-year-olds participated in 4 sessions in which they built a replica of a Lego model. During the first session, children's building competence was assessed. Based on their performance, children were classified as either expert or novice builders. Children then participated in 2 sessions in which they built alone or with a partner. There were 3 types of dyads: novice, expert, and mixed ability (expert-novice). Their performance was compared with that of novice and expert singletons. In the final session, children's ability to copy 2 new models was assessed to determine whether they generalized the skills acquired during interaction. Collaboration was more conducive to learning than independent work, and children were able to generalize their skills. However, these conclusions were qualified by the fact that children's expertise and that of their partners, the acquisition of task strategies, the quality of verbal discussion, children's tendency to observe and imitate their partners, and experts' tendency to provide guidance mediated learning.

Exact Rayleigh scattering calculations for use with the Nimbus-7 Coastal Zone Color Scanner

Abstract: For improved analysis of Coastal Zone Color Scanner (CZCS) imagery, the radiance reflected from a planeparallel atmosphere and flat sea surface in the absence of aerosols (Rayleigh radiance) has been computed with an exact multiple scattering code, i.e., including polarization. The results indicate that the single scattering approximation normally used to compute this radiance can cause errors of up to 5% for small and moderate solar zenith angles. At large solar zenith angles, such as encountered in the analysis of high-latitude imagery, the errors can become much larger, e.g.,>10% in the blue band. The single scattering error also varies along individual scan lines. Comparison with multiple scattering computations using scalar transfer theory, i.e., ignoring polarization, show that scalar theory can yield errors of approximately the same magnitude as single scattering when compared with exact computations at small to moderate values of the solar zenith angle. The exact computations can be easily incorporated into CZCS processing algorithms, and, for application to future instruments with higher radiometric sensitivity, a scheme is developed with which the effect of variations in the surface pressure could be easily and accurately included in the exact computation of the Rayleigh radiance. Direct application of these computations to CZCS imagery indicates that accurate atmospheric corrections can be made with solar zenith angles at least as large as 65 degrees and probably up to at least 70 degrees with a more sensitive instrument. This suggests that the new Rayleigh radiance algorithm should produce more consistent pigment retrievals, particularly at high latitudes.

Safety and Efficacy of Sulfamethoxazole and Trimethoprim Chemoprophylaxis for Pneumocystis carinii Pneumonia in AIDS

Abstract: The safety and efficacy of sulfamethoxazole and trimethoprim in the prevention of Pneumocystis carinii pneumonia associated with the acquired immunodeficiency syndrome (AIDS) were evaluated. Sixty patients with a new diagnosis of Kaposi's sarcoma and no history of opportunistic infections were randomly assigned to receive 800 mg of sulfamethoxazole and 160 mg of trimethoprim twice per day or no therapy. None of the 30 patients receiving sulfamethoxazole and trimethoprim developed P carinii pneumonia. Sixteen of the 30 patients receiving no suppressive therapy developed P carinii pneumonia. Development of P carinii pneumonia was associated with the stage of Kaposi's sarcoma, B subtype disease, and the presence of 0.20 × 109/L (200/mm 3 ) or fewer CD4 cells at study entry. The proportion of patients surviving and the mean length of survival were significantly greater in the treatment group compared with the control group. Adverse reactions occurred in 15 patients (50%). ( JAMA 1988;259:1185-1189)

A Model of Behavioral Self-Regulation: Translating Intention into Action

Abstract: Publisher Summary This chapter describes the model of behavioral self-regulation. The notion that behavior-specifying information is coded in memory along with many interpretative schemas provides one simple way for behavioral goals to become salient in a given situation. The Self-Consciousness Scale was designed to tap the same psychological state as was produced by self-awareness manipulations. Providing for the existence of behavioral goals and standards and their activation in a given situation constitutes the first step in a model of self-regulation. There are two prominent approaches for self-regulatory phenomena. They are the self-efficacy theory and attributional versions of helplessness theory. The chapter outlines some of the past studies that substantiate different aspects of these theories. Some portions of relatively recent work to which the theory had led are described in the chapter. In describing the model of behavioral self-regulation, the general utility of the control-theoretic ideas is described in the chapter.

Temporal variations in the separation of Brazil and Malvinas Currents

Abstract: The separation of the Brazil and Malvinas (Falkland) Currents from the western boundary is explored with the use of satellite and drifter data. The location of the separation of these boundary currents from the continental margin over a multiyear period is determined by digitizing the crossing of the surface thermal front indicative of each feature with the 1000 m isobath. Three years (July 1984 to June 1987) of 1 km resolution AVHRR data collected by the Argentina Meteorological Service and 4 years of lower resolution Global Retrieval Tape (GRT) data were used to generate a total time series extending from November 1981 to June 1987; i.e. 5 1 2 years. The mean latitudes of separation from the shelf break are 35.8 ± 1.1° for the Brazil Current and 38.6 ± 0.9° for the Malvinas Current. The along-coast ranges of the separation positions, 930 and 850 km, respectively, are quite large relative to similar statistics for the Gulf Stream or Kuroshio. Observed temporal variability suggests cyclical excursions of the currents along the coast at semi-annual and annual periods, although there is considerable interannual variation in the signal. Drifter trajectories overlaid on satellite images demonstrate events associated with the annual transition in 1984–1985. Shorter time-scale perturbations in the currents' separation latitudes occur in the 30–60 day band, which corresponds to the mesoscale eddy field. The connection of the variation in the separation with various possible forcing mechanisms is briefly discussed, along with the problem of gaining a theoretical understanding of this dynamic situation. Finally, the extensions of the two currents into the South Atlantic interior are described statistically using the high resolution data set.

Expression of the beta-nerve growth factor gene in hippocampal neurons

Abstract: In situ hybridization with complementary DNA probes for nerve growth factor (NGF) was used to identify cells containing NGF messenger RNA in rat and mouse brain. The most intense labeling occurred in hippocampus, where hybridizing neurons were found in the dentate gyrus and the pyramidal cell layer. The neuronal identity of NGF mRNA-containing cells was further assessed by a loss of NGF-hybridizing mRNA in hippocampal areas where neurons had been destroyed by kainic acid or colchicine. RNA blot analysis also revealed a considerable decrease in the level of NGF mRNA in rat dentate gyrus after a lesion was produced by colchicine. This lesion also caused a decrease in the level of Thy-1 mRNA and an increase in the level of glial fibrillary acidic protein mRNA. Neuronal death was thus associated with the disappearance of NGF mRNA. These results suggest a synthesis of NGF by neurons in the brain and imply that, in hippocampus, NGF influences NGF-sensitive neurons through neuron-to-neuron interactions.

Development of the Social Anxiety Scale for Children: Reliability and Concurrent Validity

Abstract: Although potentially important for understanding children's peer relationships, the construct of social anxiety in children has received very limited attention The present study reports on the development of the Social Anxiety Scale for Children (SASC), a 10-item self-report measure A total of 287 second through sixth graders completed the SASC and a self-report measure of trait anxiety (Revised Children's Manifest Anxiety Scale) and were assessed on their peer status using peer nomination and peer rating sociometric measures Factor analysis yielded two factors for the SASC: fear of negative evaluation (FNE) and social avoidance and distress (SAD) These factors were evaluated with respect to internal and test-retest reliability Girls reported greater FNE than boys, and children in the lower grades reported more SAD than those, in the upper elementary school grades Significant correlations between trait anxiety and the FNE and SAD factors were obtained In addition, the peer status groups (neglected,

Structure and function of human perforin.

Abstract: Perforin (P1) is a cytolytic protein with similarity to complement component C9. P1 has been described as a unique component of murine cytolytic T-cell and rat natural killer cell granules Previous studies indicated that human granules and P1 differed from murine granules and P1 in that they appeared to be cytolytically less active and lacked the haemolytic activity characteristic of P1. It has been suggested that P1, like C9, is under the control of the homologous restriction factor. Here we determine the primary structure of human P1, re-examine its functional properties, and address the question of homologous restriction.

Development of septal cholinergic neurons in culture: plating density and glial cells modulate effects of NGF on survival, fiber growth, and expression of transmitter-specific enzymes

Abstract: To characterize the role of NGF in the development of forebrain cholinergic neurons, we established primary cell culture systems to grow these cells under controlled in vitro conditions. Cultures of dissociated cells were prepared from the septal area of fetal (E17) rats, which contained part of the group of basal forebrain cholinergic neurons. Cultures were treated either with NGF (100 ng/ml) or with an antiserum against NGF (1:500 dilution). To assess the influence of non-neuronal cells, 2 types of high-density cultures were prepared: mixed neuronal-glial cultures and pure neuronal cultures. Cholinergic neurons were identified using choline acetyltransferase (ChAT) immunocytochemistry and AChE cytochemistry. Receptors for NGF (NGF-R) were located immunocytochemically using monoclonal antibodies against rat NGF-R. We report that, first, NGF-R are exclusively localized on cholinergic neurons in septal cultures. All neurons labeled with antibodies against NGF-R also contained AChE. Twenty-one percent of all AChE-positive neurons were not stained in NGF-R immunocytochemistry (AChE has earlier been shown to be colocalized with ChAT in septal cultures). Second, NGF treatment increases and anti-NGF treatment reduces the number of AChE-positive neurons in cultures of low plating density, suggesting that NGF promotes survival of septal cholinergic neurons in these cultures. In cultures of high plating density, NGF increased the number of NGF-R and ChAT-positive neurons without affecting the number of AChE-positive neurons in these cultures. These results suggest that exogenous NGF is not required for survival of cholinergic neurons in high-density cultures but stimulates the expression of ChAT and NGF-R. Third, NGF stimulates fiber growth of septal cholinergic neurons, as assessed by computerized image analysis of AChE-positive neurons. Fourth, NGF specifically increases ChAT and AChE activities in septal cultures. These NGF-mediated increases in enzyme activities are more pronounced when neurons are grown together with glial cells. In pure neuronal cultures, NGF increased ChAT and AChE activities by 101 and 16%, and in mixed neuronal-glial cultures by 318 and 87%, respectively. Anti-NGF blocked the effects of NGF but failed to reduce ChAT and AChE activities below control levels in cultures of high plating density. Fifth, astrocytes attenuate the expression of ChAT and AChE by septal neurons in the absence of NGF.(ABSTRACT TRUNCATED AT 400 WORDS)

Destruction of Rat Islet Cell Monolayers by Cytokines: Synergistic Interactions of Interferon-γ, Tumor Necrosis Factor, Lymphotoxin, and Interleukin 1

Abstract: An assay was developed to detect the cytotoxic effects of cytokines on rat pancreatic islet cells in monolayer culture. Cell lysis was detected by a 51Cr-release assay after 4 days of incubation with various cytokines. When tested alone, murine (rat and mouse) interferon-gamma (mIFN-gamma) produced a small dose-dependent lysis of islet cells; human IFN-gamma, mouse IFN-alpha/beta, interleukins 1 and 2 (IL-1 and IL-2), tumor necrosis factor (TNF), and lymphotoxin (LT) were inactive. When added together, the following combinations of cytokines showed synergistic cytotoxic effects: TNF (or LT) plus IL-1, TNF (or LT) plus mIFN-gamma, and IL-1 plus mIFN-gamma. These results indicate that the cytokine products of mononuclear cells of the immune system, IFN-gamma, TNF, LT, and IL-1 have strong synergistic cytotoxic effects on islet cells and therefore may act as direct chemical mediators of islet beta-cell destruction in type I (insulin-dependent) diabetes.

Rat beta-nerve growth factor sequence and site of synthesis in the adult hippocampus.

Abstract: A rat b-nerve growth factor (NGF) genomic sequence encoding the entire 3′ exon of preproNGF was cloned, and its nucleotide sequence was determined. Rat NGF shows very high homology with other known NGFs in both the prepropeptide and the 3′ untranslated regions. The presumptive signal sequence, the cysteine residues important for tertiary structure, possible glycosylation sites, and dibasic amino acids required for proteolytic cleavage to mature NGF are conserved across species. Comparison of the hydrophobicity plots and amino acid sequences revealed an evolutionary divergent domain on the external surface of NGF, which may account for the poor immunologic crossreactivities of the various NGFs. In situ hydridization with a rat-specific oligodeoxynucleotide indicated high levels of NGF mRNA synthesis in both hippocampal granule and pyramidal cell layers. These results are consistent with one role for NGF in the CNS as a neuronally released, retrogradely transported neurotrophic factor for basal forebrain cholinergic neurons.

Cerebral metabolic effects of a verbal fluency test: A PET scan study

Abstract: Sixteen normal volunteers were studied with [F-18] fluorodeoxyglucose and positron emission tomography scans during behavioral activation with a verbal fluency test, and 35 age-matched controls were studied with resting-state scans. There was an overall increase of the cerebral glucose metabolic rate of 23.3% during verbal fluency activation, compared to the resting state, with the greatest activation in bilateral temporal and frontal lobes. A negative correlation between test performance scores and indices of metabolism was found in frontal, temporal, and parietal regions. Damage to the left frontal lobe maximally affects scores on verbal fluency tests, but performing the test activates a network of regions, of which the left frontal lobe is only one. Proficient performance in verbal fluency seems to require less metabolic activation than poor performance, perhaps because of the efficiency of cognitive strategies employed.

The use of hydrophobic synthetic glycosides as acceptors in glycosyltransferase assays

Abstract: A general method is described for the assay of glycosyltransferase activity, which makes use of synthetic glycoside acceptors attached to hydrophobic aglycones. The products formed by incubation of an enzyme with acceptor and radiolabelled sugarnucleotide can then be rapidly (one minute) separated from interfering radioactivity by adsorption on to reverse-phase C-18 cartridges. After aqueous washing, products are easily isolated by elution with methanol. The utility of the method for the assay of β(1–4)galactosyltransferase, α(1–2)fucosyltransferase andN-acetylglucosaminyltransferase I and V is demonstrated.

MHC polymorphism pre-dating speciation.

Abstract: Two features distinguish the polymorphism of the major histocompatibility complex (MHC) loci from that of other loci: its high diversity and the large genetic distance between MHC alleles. More than 100 alleles exist in natural populations in the mouse at each of the functional class I and class II alleles, all alleles occurring at frequencies that cannot be explained by recurrent mutations. Some of the alleles differ by approximately 70 nucleotides in the coding region alone and some of the products of the allelic genes differ by more than 50 amino acids. It has generally been assumed that these differences accumulated after species inception. Here, we present evidence for an alternative explanation of the origin of MHC polymorphism: a large part of the MHC polymorphism pre-dates speciation and is passed on from species to species. We describe allelic differences that must have arisen before the separation of mice and rats from a common ancestor more than 10 million years ago.

Estimating Primate Densities from Transects in a West African Rain Forest: A Comparison of Techniques

Abstract: (1) We used two line-transect survey techniques and five analytical methods to assess the densities of social groups of seven diurnal primate species resident on Tiwai Island, Sierra Leone, West Africa. (2) A modified standard species-specific strip-width estimation technique was applied to data from twenty-eight single-observer transect samples, each 6 km in length. (3) The second method employed seventeen sweep samples where three observers simultaneously walked parallel transects 100 m apart and 1 km in length. This method used both sightings and localization of vocalizations for density estimation. (4) The third method transformed sighting rates from the single-observer samples into density estimates by incorporating sighting rates and densities from sweep samples into calibration factors. (5) We used long-term data on home-range size and overlap to estimate density for three species for which we had sufficient data. (6) The fifth method employed the hazard-rate model of Hayes & Buckland (1983) which involved transforming estimates of distance to the first sighted individual into estimates of distance to the group centre. (7) The rank orders by species of density estimates produced by all analytical techniques were identical except for the sweep-quadrat method. We found no significant differences among density estimates produced by different analytical methods, except for the C. diana density produced by the sweep samples. (8) We recommend the use of both relatively long single-transect samples and also more localized multi-observer sweep samples. These techniques allow use of a variety of analytical methods.