Showing papers by "University of Miami published in 1989"

Assessing Coping Strategies: A Theoretically Based Approach

Abstract: We developed a multidimensional coping inventory to assess the different ways in which people respond to stress. Five scales (of four items each) measure conceptually distinct aspects of problem-focused coping (active coping, planning, suppression of competing activities, restraint coping, seeking of instrumental social support); five scales measure aspects of what might be viewed as emotional-focused coping (seeking of emotional social support, positive reinterpretation, acceptance, denial, turning to religion); and three scales measure coping responses that arguably are less useful (focus on and venting of emotions, behavioral disengagement, mental disengagement). Study 1 reports the development of scale items. Study 2 reports correlations between the various coping scales and several theoretically relevant personality measures in an effort to provide preliminary information about the inventory's convergent and discriminant validity. Study 3 uses the inventory to assess coping responses among a group of undergraduates who were attempting to cope with a specific stressful episode. This study also allowed an initial examination of associations between dispositional and situational coping tendencies.

Effect of mild hypothermia on ischemia-induced release of neurotransmitters and free fatty acids in rat brain.

Abstract: We have demonstrated previously that mild intraischemic hypothermia confers a marked protective effect on the final histopathological outcome. The present study was carried out to evaluate whether this protective effect involves changes in the degree of local cerebral blood flow reductions, tissue accumulation of free fatty acids, or alterations in the extracellular release of glutamate and dopamine. Rats whose intraischemic brain temperature was maintained at 36 degrees C, 33 degrees C, or 30 degrees C were subjected to 20 minutes of ischemia by four-vessel occlusion combined with systemic hypotension. Levels of local cerebral blood flow, as measured autoradiographically, were reduced uniformly in all experimental animals at the end of ischemia by gas chromatography after tissue extraction and separation by thin layer chromatography. A massive ischemia-induced accumulation of individual free fatty acids was observed in animal groups whose intraischemic brain temperature was maintained at either 36 degrees C or 30 degrees C. Extracellular neurotransmitter levels were measured by microdialysis; the perfusate was collected before, during, and after ischemia. In rats whose intraischemic brain temperature was maintained at 36 degrees C, dopamine and glutamate increased significantly during ischemia and the early period of recirculation (by 500-fold and sevenfold, respectively). In animals whose brain temperature was maintained at 33 degrees C and 30 degrees C, the release of glutamate was completely inhibited, and the release of dopamine was significantly attenuated (by 60%). These results suggest that mild intraischemic hypothermia does not affect the ischemia-induced local cerebral blood flow reduction or free fatty acid accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Rodent models of cerebral ischemia.

Abstract: The use of physiologically regulated, reproducible animal models is crucial to the study of ischemic brain injury--both the mechanisms governing its occurrence and potential therapeutic strategies. Several laboratory rodent species (notably rats and gerbils), which are readily available at relatively low cost, are highly suitable for the investigation of cerebral ischemia and have been widely employed for this purpose. We critically examine and summarize several rodent models of transient global ischemia, resulting in selective neuronal injury within vulnerable brain regions, and focal ischemia, typically giving rise to localized brain infarction. We explore the utility of individual models and emphasize the necessity for meticulous experimental control of those variables that modulate the severity of ischemic brain injury.

Evidence for metalloproteinase and metalloproteinase inhibitor imbalance in human osteoarthritic cartilage.

Abstract: Cartilage specimens from tibial plateaus, obtained from 13 osteoarthritic (OA) patients and seven controls, were selected from three regions: zone A, center of fibrillated area; zone B, area adjacent to fibrillation, and zone C, remote region of plateau. Acid and neutral metalloproteinases and tissue inhibitor of metalloproteinase (TIMP) were extracted with 2 M guanidine. Methods were developed to selectively destroy either proteinases or TIMP to prevent cross-reaction during assay. Acid and neutral proteinases were elevated approximately 150% in OA; TIMP was elevated approximately 50%. A positive correlation (r = 0.50) was found between acid and neutral proteinase activities in OA, but not in controls. Both proteinases were elevated two-to threefold in zones A, B, and C. However, the self-active form of the acid metalloproteinase was elevated only in zones A and B (200%); it correlated well with the Mankin scores, whereas the total activities did not. TIMP was elevated (50%) only in zones A and B. Both the proteinase levels and the Mankin score were elevated to a greater extent in the medial, than in the lateral, compartment. Titration of TIMP against the two metalloproteinases indicates that there is a small excess of inhibitor over enzymes in normal cartilage. In OA, TIMP does not increase to the same extent as the proteinases; the resultant excess of proteinases over TIMP may contribute to cartilage breakdown.

Concept and application of limbal stem cells.

Abstract: Cumulative reported evidence indicates that some fraction of limbal basal epithelial cells are the stem cells for corneal epithelial cell proliferation and differentiation. Limbal epithelium is therefore crucial in maintaining the cell mass of corneal epithelium under normal conditions and plays an important role in corneal epithelial wound healing. Deficiency or absence of limbal stem cells explains well the pathogenesis of several ocular surface disorders characterised by defective conjunctival transdifferentiation or conjunctivalisation of cornea. This paper reviews and updates the basic concept of stem cells, the reported findings of limbal stem cells for corneal epithelium, and their therapeutic applications. Through this review, one hopes to gain a more complete understanding and increase proficiency in treating these diseases.

Bone transplantation and human immunodeficiency virus. An estimate of risk of acquired immunodeficiency syndrome (AIDS).

Abstract: The possibility of transplanting a bone allograft from a donor infected with human immunodeficiency virus (HIV) is remote, provided there is a combination of rigorous donor selection and exclusion, screening for the HIV antigen and antibody, and histopathologic studies of donor tissues The chance of obtaining a bone allograft from an HIV-infected donor who failed to be excluded by the above techniques is calculated to be one in well over a million, using average estimates On the other hand, if adequate precautions are not taken (for example, by testing only for antibodies to HIV), the risk might be as high as one in 161

Cellular Mechanisms Regulating [Ca2+]i Smooth Muscle

Abstract: The preceding chapters establish the primary role of Ca2+ in the activation of smooth muscle contractile proteins. In this chapter we discuss the Ca2+ transport mechanisms that determine the intracellular Ca2+ concentration ([Ca2+U and thus regulate smooth muscle contraction. Two integrated membrane systems are involved in the control of smooth muscle [Ca2+l;: (a) the plasmalemma, which is under the control of the membrane potential (Em) and agonists such as neurotransmitters hormones and autocoids, and (b) the sarcoplasmic reticulum, which is under the control of second messengers. Both membranes form a barrier to an approximately IO,OOO-foid concentration gradient; thus, an increase in permeability to Ca2+ leads to an increase in [Ca2+l;, while active ATP-fueled Ca2+ pumping and possibly Na+ -Ca2+ exchange leads to a decrease in [Ca2+l;. Plasmalemmal Ca2+ permeability is regulated by the voltage gated Ca2+ channels (VGCs) and by chemical gating of receptor operated channels (ROCs) (11, 83). In some cases, agonists also inhibit the Ca2+ extrusion pump (23). The mem­ brane potential is determined by ionic concentration gradients and per­ meabilities according to the Goldman equation and is regulated close to the K+ equilibrium potential by the opening or closing of K+ channels (11).

Photochemical source of biological substrates in sea water: implications for carbon cycling

Abstract: DISSOLVED organic carbon (DOC) in sea water represents one of the largest reservoirs of carbon on the earth1. The main fraction of this DOC is generally believed to be composed of old2, biologi-cally refractory material3 such as humic substances, for which the removal mechanisms remain largely unknown. One potentially important removal process in the ocean that has not been investi-gated is the photochemical breakdown of this DOC in the photic zone to form biologically labile organic products. Here we show that biological uptake of pyruvate is highly correlated to its rate of photochemical production in sea water (r = 0.964), and that the photochemical precursor(s) of pyruvate is from the fraction of DOC having a nominal molecular weight of 500. This is the first evidence that photochemical breakdown of high-molecular-weight marine DOC, which is presumably biologically refractory, results in the production of a compound that is used by plankton as a substrate. Our results have important implications for the oceanic carbon cycle, particularly with respect to planktonic-food-web dynamics and the global carbon budget.

Child maltreatment: Child maltreatment and attachment theory

Abstract: The study of child maltreatment has grown exponentially in the years since the identification of the “battered child syndrome” (Kempe, Silverman, and Steele, 1962). In that time the area has experienced many of the conflicts and missteps to be expected in an emerging field. Underlying these problems is the lack of a single, comprehensive theoretical approach to child maltreatment (Newberger, Newberger, and Hampton, 1983). It is the purpose of this chapter to examine attachment theory in regard to its adequacy in accounting for the existing data on child abuse and child neglect. Because child abuse was identified as a social issue earlier than child neglect, it will be discussed first. However, in regard to the early literature, the dichotomy is difficult, and sometimes impossible, to make because cases of neglect or abuse-with-neglect were included indiscriminately under the rubric of abuse. One goal of this chapter will be to disentangle the conditions and consider separately how relevant attachment theory is to understanding them. The first studies of child abuse focused on identifying the characteristics of abusers. Although abusers were not usually found to be mentally ill, they were often described as more aggressive, punitive, domineering, and inconsistent than nonabusing parents. As more cases of less severe child abuse were reported and investigated, the incidence of clear parental deviance decreased while the evidence for cultural and child influence increased. The societal variables associated with abuse included unemployment, job dissatisfaction, single-parent families, and social isolation of low-income, multiproblem families.

Division and differentiation of isolated CNS blast cells in microculture.

Abstract: The mechanism of transformation of the overtly similar cells of the neural plate into the numerous and diverse cell types of the mature vertebrate central nervous system (CNS) can better be understood by studying the clonal development of isolated CNS precursor cells. Here I describe a culture system in which blast cells (cells capable of division) isolated from embryonic day 13.5-14.5 rat forebrain can divide and differentiate into a variety of clonal types. Most clones contain only neurons or glia; 22% contain both neurons and non-neuronal cells. For the division of blast cells, live conditioning cells need to be present indicating that environmental signals influence proliferation. Heterogeneous clones develop in homogeneous culture conditions, so factors intrinsic to the blast cells are probably important in determining the number and type of clonal progeny.

Ion channels and regulation of intracellular calcium in vascular endothelial cells.

Abstract: Endothelial cells in vivo form an interface between flowing blood and vascular tissue, responding to humoral and physical stimuli to secrete relaxing and contracting factors that contribute to vascular homeostasis and tone. The activation of endothelial cell-surface receptors by vasoactive agents is coupled to an elevation in cytosolic Ca2+, which is caused by Ca2+ entry via ion channels in the plasma membrane and by Ca2+ release from intracellular stores. Ca2+ entry may occur via four different mechanisms: 1) a receptor-mediated channel coupled to second messengers; 2) a Ca2+ leak channel dependent on the electrochemical gradient for Ca2+; 3) a stretch-activated nonselective cation channel; and 4) internal Na+-dependent Ca2+ entry (Na+-Ca2+ exchange). The rate of Ca2+ entry through these ion pathways can be modulated by the resting membrane potential. Membrane potential may be regulated by at least two types of K channels: inwardly rectifying K channels activated upon hyperpolarization or shear stress; a...

Re-evaluation of the linkage relationship between chromosome 11p loci and the gene for bipolar affective disorder in the old order amish

Abstract: Reanalysis of an Old Order Amish pedigree, to include several new individuals and two changes in clinical status, markedly reduces the probability of linkage between bipolar affective disorder and the Harvey-ras-1 oncogene and insulin loci on chromosome 11. This linkage can be excluded using a large lateral extension of the original Amish pedigree.

Calibration of respiratory inductive plethysmograph during natural breathing

Abstract: We describe a single-posture method for deriving the proportionality constant (K) between rib cage (RC) and abdominal (AB) amplifiers of the respiratory inductive plethysmograph (RIP). Qualitative diagnostic calibration (QDC) is based on equations of the isovolume maneuver calibration (ISOCAL) and is carried out during a 5-min period of natural breathing without using mouthpiece or mask. In this situation, K approximates the ratio of standard deviations (SD) of the uncalibrated changes of AB-to-RC volume deflections. Validity of calibration was evaluated by 1) analyzing RIP waveforms during an isovolume maneuver and 2) comparing changes of tidal volume (VT) amplitude and functional residual capacity (FRC) level measured by spirometry (SP) with RIP values. Comparisons of VT(RIP) to VT(SP) were also obtained in a variety of postures during natural (uninstructed) preferential RC and AB breathing and with voluntary changes of VT amplitude and FRC level. VT(RIP)-to-VT(SP) comparisons were equal to or closer than published reports for single posture, ISOCAL, multiple- and linear-regression procedures. QDC of RIP in supine posture with comparisons to SP in that posture and others showed better accuracy in horizontal than upright postures.

Survival in children with perinatally acquired human immunodeficiency virus type 1 infection.

Abstract: We describe our experience at Jackson Memorial Hospital in Miami, Florida, with 172 children who were given diagnoses of perinatally acquired infection with human immunodeficiency virus ty...

Unexpected changes in the oxic/anoxic interface in the Black Sea

Abstract: THE Black Sea is the largest anoxic marine basin in the world today1. Below the layer of oxygenated surface water, hydrogen sulphide builds up to concentrations as high as 425 μM in the deep water down to a maximum depth of 2,200 m (ref. 2). The hydrographic regime is characterized by low-salinity surface water of river origin overlying high-salinity deep water of Mediterranean origin1,3. A steep pycnocline, centred at about 50 m is the primary physical barrier to mixing and is the origin of the stability of the anoxic (oxygen/hydrogen sulphide) interface. Here we report new observations, however, that indicate dramatic changes in the oceanographic characteristics of the anoxic interface of the Black Sea over decadal or shorter timescales. The anoxic, sulphide-containing interface has moved up in the water column since the last US cruises in 1969 and 1975. In addition, a suboxic zone overlays the sulphide-containing deep water. The expected overlap of oxygen and sulphide was not present. We believe that these observations result from horizontal mixing or flushing events that inject denser, saltier water into the relevant part of the water column. It is possible that man-made reduction in freshwater inflow into the Black Sea could cause these changes, although natural variability cannot be discounted.

Can the Lambert-Beer law be applied to the diffuse attenuation coefficient of ocean water?

Abstract: Radiative transfer theory is combined with a bio-optical model of Case 1 waters and an optical model of the atmosphere to simulate the transport of radiation in the ocean-atmosphere system. The results are treated as experimental data to study the downwelling irradiance attenuation coefficient. It is shown that the downwelling irradiance attenuation coefficient just beneath the surface and the mean downwelling irradiance attenuation coefficient from the surface to the depth where the irradiance falls to 10% of its value at the surface can be corrected for the geometric structure of the in-water light field to yield quantities that are-to a high degree of accuracyinherent optical properties. For Case 1 waters these geometry-corrected attenuation coefficients arc shown to satisfy the Lambert-Beer law with a maximum error of 5-10% depending on wavelength. This near-validity of the Lambert-Beer law, when there are compelling reasons to believe that it should fail, is shown to result from three independent facts: the dependence of the diffuse attenuation coefficients on the geometric structure of the light field can be removed; pure seawater is a much better absorber than scatterer at optical frequencies; and the phase function for particles suspended in the ocean differs significantly from that of pure seawater. Finally, it is shown that extrapolation of the corrected diffuse attenuation coefficients to the limit c --* c, yields quantities that are within 2% of the corresponding quantities that would be measured for an ocean consisting of pure seawater with the sun at zenith and the atmosphere removed.

How should multifaceted personality constructs be tested? Issues illustrated by self-monitoring, attributional style, and hardiness.

Abstract: Two or more dimensions unintentionally varied simultaneously are said to be confounded, but several theories in personality intentionally combine 3 or more distinct qualities. Researchers using these theories sum the qualities before testing predictions. How wise is this practice? The practice appears to derive from 2 distinct lines of reasoning. One of them assumes that the component dimensions converge on a single underlying quality (latent variable) that each reflects imperfectly. The other assumes a synergy among dimensions. Issues arising from each line of reasoning are illustrated by examining self-monitoring, attributional style, and hardiness. Conclusions are that (a) information is lost whenever a latent variable theory is tested solely by a composite and (b) a synergistic theory can be tested only through a statistical interaction.

A new scale for the assessment of functional status in Alzheimer's disease and related disorders

Abstract: Assessment of the functional competencies of patients with dementia is typically conducted in an indirect manner. Psychological tests of cognition or descriptions by relatives or other caregivers are often used to make judgments as to the patient's ability to adapt to the demands of the environment. However, these methods have built-in biases. The need for direct assessment of functional status was addressed by developing a standardized operational procedure to examine areas of functional competence which may become impaired in Alzheimer's disease and other related memory disorders. The resulting instrument has high interrater and test-retest reliabilities. Convergent validity is evidenced by significant correlations between the scale and established measures of functional status. Patients with Alzheimer's disease exhibited deficits in functional capacities relative to age-equivalent normal controls and to elderly patients with a primary major depression.

The importance of brain temperature in cerebral ischemic injury.

Abstract: Observations of cerebroprotection by hypothermia are not new, though traditional approaches have tended to employ overall reductions of wholebody temperature of rather sizable magnitude. In contrast, our laboratory first suspected several years ago that small fluctuations of brain temperature might account in part for variability in the extent of tissue injury encountered in animal models of reversible ischemia

Brevetoxins: unique polyether dinoflagellate toxins.

Abstract: Brevetoxins are lipid-soluble polyether marine toxins of unique structure and pharmacological function. Toxins are active in vivo in the nanomolar to picomolar concentration range and in vitro in isolated neuromuscular or giant axon preparations and in single-cell or subcellular model systems. Their effect is excitatory, mediated by the enhancement of cellular Na+ influx. Brevetoxins bind at site 5 on the voltage-sensitive sodium channel, a specificity shared with ciguatoxin. This site is allosterically linked to other natural toxin binding sites on the channel.

The incidence of Hill-Sachs lesions in initial anterior shoulder dislocations

Abstract: We undertook a prospective study using arthroscopy to determine the intraarticular derangement caused by initial anterior shoulder dislocations. Of our 32 patients, 15 (47%) had a grade I, grade II, or grade III Hill-Sachs lesion. The patients were 29 men and 3 women whose ages ranged from 15 to 28 years (mean 22 years). All of the patients studied were United States military personnel or members of their families. None of the patients had had prior injuries of the affected shoulder, and all underwent arthroscopy within 72 h of injury. Few reports describe a Hill-Sachs lesion in a patient following a single anterior dislocation. Early reports of this lesion were based on indirect (radiographic) evidence. Our arthroscopic findings indicate that the incidence of this lesion after one anterior dislocation is higher than previously thought.

Evolution of urea synthesis in vertebrates: the piscine connection

Abstract: Elasmobranch fishes, the coelacanth, estivating lungfish, amphibians, and mammals synthesize urea by the ornithine-urea cycle; by comparison, urea synthetic activity is generally insignificant in teleostean fishes. It is reported here that isolated liver cells of two teleost toadfishes, Opsanus beta and Opsansus tau, synthesize urea by the ornithine-urea cycle at substantial rates. Because toadfish excrete ammonia, do not use urea as an osmolyte, and have substantial levels of urease in their digestive systems, urea may serve as a transient nitrogen store, forming the basis of a nitrogen conservation shuttle system between liver and gut as in ruminants and hibernators. Toadfish synthesize urea using enzymes and subcellular distributions similar to those of elasmobranchs: glutamine-dependent carbamoyl phosphate synthethase (CPS III) and mitochondrial arginase. In contrast, mammals have CPS I (ammonia-dependent) and cytosolic arginase. Data on CPS and arginases in other fishes, including lungfishes and the coelacanth, support the hypothesis that the ornithine-urea cycle, a monophyletic trait in the vertebrates, underwent two key changes before the evolution of the extant lungfishes: a switch from CPS III to CPS I and replacement of mitochondrial arginase by a cytosolic equivalent.

Cognitive impairments associated with early Parkinson's disease.

Abstract: We administered a battery of cognitive tests to 41 recently diagnosed Parkinson patients and 41 controls to assess the early neuropsychological changes associated with Parkinson9s disease (PD). Parkinson subjects did as well as controls on tasks assessing attention and select language and visuospatial measures. However, PD subjects did significantly worse on embedded figures, facial recognition, proverbs, and verbal and figural memory measures, and made more perseverative responses on a set shifting task. A discriminant function of measures of proverbs, embedded figures, and memory accounted for 22% of the variance between groups. These data suggest that the cognitive changes in early PD are more pervasive than originally described and may reflect the onset of a more widespread pathologic process.

Ocean color: Availability of the global data set

Abstract: The use of satellite observations of ocean color to provide reliable estimates of marine phytoplankton biomass on synoptic scales is examined. An overview is given of the Coastal Zone Color Scanner data processing system. The archiving and distribution of ocean color data are discussed, and NASA-sponsored archive sites are listed.