Showing papers by "University of Miami published in 1984"

The effects of high-dose corticosteroids in patients with septic shock. A prospective, controlled study.

Abstract: To determine whether corticosteroids are efficacious in severe septic shock, we conducted a prospective study of 59 patients randomly assigned to a methylprednisolone, dexamethasone, or control group. Patients were treated 17.5 +/- 5.4 hours (mean +/- S.E.M.) after the onset of shock, and 55 patients required vasopressor agents. Early in the hospital course, reversal of shock was more likely in patients who received corticosteroids than in those who did not. Four (19 per cent) of 21 methylprednisolone-treated, 7 (32 per cent) of 22 dexamethasone-treated, and none of 16 control patients had reversal of shock 24 hours after drug administration (corticosteroid groups vs. control group, P less than 0.05). Patients treated with corticosteroids within four hours after the onset of shock had a higher incidence of shock reversal (P less than 0.05). At 133 hours after drug administration, 17 (40 per cent) of 43 corticosteroid-treated patients had died, and 11 (69 per cent) of 16 control patients had died (P less than 0.05). However, these differences in reversal of shock and survival disappeared later in the course. Overall, 16 (76 per cent) of 21 patients receiving methylprednisolone, 17 (77 per cent) of 22 patients receiving dexamethasone, and 11 (69 per cent) of 16 controls in the hospital died. We conclude that corticosteroids do not improve the overall survival of patients with severe, late septic shock but may be helpful early in the course and in certain subgroups of patients.

The Social Relations Model

Abstract: Publisher Summary The Social Relations Model represents one method of studying two-person relationships. It attempts to separate the effects of persons and dyad. The Social Relations Model has three potential contributions to the study of dyads. First, it provides a purely methodological-statistical solution to the analysis of dyadic data. The Social Relations Model represents a new approach to the analysis of dyadic data structures. Second, the model can provide social psychology with better procedures to resolve the theoretical issues of the discipline. Third, the model is useful because it looks at social behavior as simultaneously operating at multiple levels. Very different principles operate at these different levels and only by simultaneously examining social behavior at different levels, the complexity and simplicity of social life can be fully appreciated.

Efficacy of Methylprednisolone in Acute Spinal Cord Injury

Abstract: A multicenter double-blind randomized trial was conducted to examine the efficacy of a high dose of methylprednisolone (1,000-mg bolus and daily thereafter for ten days) compared with a standard dose (100-mg bolus and daily thereafter for ten days) in 330 patients with acute spinal cord injury. No difference in neurological recovery of motor function or pinprick and light touch sensation was observed between the two treatment groups six weeks and six months after injury. The lack of a treatment effect was independent of the severity of the initial lesion or the time from injury to starting treatment. Although not statistically significant, early case fatality was greater in the high-dose protocol (relative risk of 3.1 and 1.9, ≤ 14 and 15 to 28 days after injury, respectively) but not from 29 to 210 days after injury. Wound infections of both trauma and operative sites were more prevalent in the high-dose regimen (relative risk of 3.6). (JAMA1984;251:45-52)

Early interactions between infants and their postpartum depressed mothers

Abstract: Early face-to-face play interactions in which mothers have been instructed to “look depressed” result in disorganized, distressed behavior on the part of the infants (Cohn & Tronick, 1983). During this manipulation the infants more frequently looked wary, gaze averted, protested, and attempted to elicit responses from the mother, much like the infant interacting with a still-face mother attempts to reinstate their normal interaction (Fogel, Diamond, Langhorst, & Demos, 1982; Stoller & Field, 1982; Trevarthen, 1977; Tronick, Als, Adamson, Wise, & Brazelton, 1978). The infants’ distressed behavior continued even after the mothers resumed their normal behavior. Although the Cohn and Tronick (1983) study was intended to be a simulation of interactions between depressed mothers and infants, it is possible that infants of naturally depressed mothers may be accustomed to depressed behavior and thus may not act distressed when she is invited to “look depressed.” In the present study we investigated whether infants of mothers who became depressed postpartum.would behave like infants of,nondepressed mothers who were invited to “look depressed.” Twenty-four mothers (12 depressed, 12 nondepressed) and their infants were videotaped during face-to-face interactions when the infants were three months old. The “depressed” mothers had been referred to us by the obstetric unit social worker because they looked depressed during the lying-in period. This group of mothers and a randomly selected group of mothers delivering on the same unit were invited to participate in the study when their infants were three months old. All mothers were given the Beck Depression Inventory (Beck, Ward, Mendelson, Mock, & Erbaugh, 1969) and the State-Trait Anxiety Inventory (Spielberger, Gorsuch, & Lushene, 1970). Only those mothers who received scores of 16 or above on the Beck Depression inventory (BDI) were recruited for the “depressed” mothers’ group. The group of nondepressed mothers (scores 14 on BDI) were then selected from the random sample to

Acquired immunodeficiency syndrome in infants.

Abstract: Fourteen infants with clinical and laboratory features of an acquired immunodeficiency syndrome were identified in a single metropolitan area from November 1980 to July 1983. Patients were predominantly of Haitian parentage, although two cases occurred in offspring of non-Haitian intravenous drug abusers. Only one patient had received a blood transfusion before the development of clinical findings. The predominant clinical findings included failure to thrive, persistent infection of the oral mucosa by Candida albicans, chronic pulmonary infiltrates, hepatosplenomegaly, lymphadenopathy, and diarrhea. Immunologic studies showed most of the infants to have inverted ratios of T-cell subsets, greatly increased immunoglobulin levels, and circulating immune complexes. Lymphopenia was not common, as it is in adult patients. Infectious agents responsible for opportunistic infections in this series included Pneumocystis carinii, herpesviruses, particularly cytomegalovirus, and C. albicans. Bacterial infections were common, and gram-negative sepsis was the major cause of death in the seven infants who have died. At autopsy, two infants had disseminated lymphadenopathic Kaposi's sarcoma. These observations suggest the likelihood of transplacental, perinatal, or postnatal transmission of an as yet unidentified infectious agent that causes this disease.

Tuberculosis atypical mycobacteriosis and the acquired immunodeficiency syndrome among Haitian and non-Haitian patients in South Florida.

Abstract: To study the association between mycobacterial disease and the acquired immunodeficiency syndrome, we reviewed the records of all cases of tuberculosis and all cases of the syndrome reported in Dade County, Florida, from January 1980 through June 1983. Tuberculosis was diagnosed in 27 of 45 Haitians with the syndrome, but in only 1 of 37 non-Haitians with the syndrome (p less than 0.001). Among the 27 Haitians with the syndrome and tuberculosis, 19 had extrapulmonary tuberculosis, whereas among 286 Haitian patients with tuberculosis without the syndrome, only 56 had extrapulmonary tuberculosis (p less than 0.001). Tuberculosis preceded the syndrome by 1 to 17 months (mean, 6) in 22 patients. In 10 patients with the syndrome and positive sputum cultures who were treated with conventional antituberculosis drugs, the cultures became negative within 1 to 4 months and tuberculosis did not recur. The frequency of disseminated atypical mycobacteriosis or positive sputum cultures for atypical mycobacteria was not significantly different between Haitian (11.3%) and non-Haitian (8.3%) patients with the syndrome.

Glomerular Lesions in the Acquired Immunodeficiency Syndrome

Abstract: Between January 1982 and December 1983, 75 patients with the acquired immunodeficiency syndrome were identified in our hospitals: 35% used intravenous drugs, 50% had proteinuria in excess of 0.5 g/dL, and 10% were nephrotic. Glomerular changes seen at autopsy in 36 patients included frequent mesangial lesions and deposits associated with mild asymptomatic proteinuria. Focal and segmental glomerular sclerosis was found in 5 patients and 4 of these had the nephrotic syndrome. Whereas reversible episodes of acute renal failure were not uncommon, terminal episodes of acute renal insufficiency occurred in 14 patients. The short survival of these patients may prevent the development of chronic renal failure.

Mother-stranger face discrimination by the newborn

Abstract: Newborn infants discriminate their mother's face from the face of a stranger shortly after birth. The neonates (M age=45 hours) showed an initial preference for their mother's face. The mother's face (or face and voice) was then presented to the neonates for repeated trials until the infant reached an habituation criterion. In a subsequent discrimination test the infants looked significantly longer at the stranger's face, suggesting that the mother's face was discriminated after very limited experience. Although voice cues were not required for this discrimination, the possibility remains that other cues, such as the mother's odor, may facilitate the discrimination of her face.

Lipid Peroxidation In Vivo Induced by Reversible Global Ischemia in Rat Brain

Abstract: It has been hypothesized that ischemia, followed by reperfusion, facilitates peroxidative free-radical chain processes in brain. To resolve this question, rats were subjected to reversible global ischemia. From coronal sections of brains frozen in situ, small (ca. 2 mg) amounts of tissue were sampled from neocortex, hippocampus, and thalamus of both cerebral hemispheres of four groups of rats exposed to 30 min cerebral ischemia followed by 0, 30, 60, and 240 min of reperfusion, and from a control group subjected to the same operative procedures, except for the induction of ischemia. Heptane-solubilized total lipid extracts from these samples were analyzed spectroscopically in the 190-330 nm range for content of isolated (nonconjugated) double bonds and of conjugated diene structures; the latter are formed from isolated double bonds during peroxidation of unsaturated fatty acids. Spectra derived from tissue regions of rats subjected to ischemia, or ischemia followed by reperfusion, were compared to averaged, region-specific control spectra and were normalized to the original content of isolated double bonds in the peroxidized samples. The resultant difference spectra were analyzed in terms of ratios of conjugated diene concentration to the concentration of isolated double bonds originally at risk in the specific tissue zones considered. The peak representing conjugated diene formation was centered at 238 +/- 1 nm and was usually well resolved when the molar ratio [conjugated diene]/[isolated double bonds], expressed as a percentage [( CD]/[IDB]), was greater than 0.25%.(ABSTRACT TRUNCATED AT 250 WORDS)

Ion Conductance and Selectivity of Single Calcium-activated Potassium Channels in Cultured Rat Muscle

Abstract: The conductance and selectivity of the Ca-activated K channel in cultured rat muscle was studied. Shifts in the reversal potential of single channel currents when various cations were substituted for Ki+ were used with the Goldman-Hodgkin-Katz equation to calculate relative permeabilities. The selectivity was Tl+ greater than K+ greater than Rb+ greater than NH4+, with permeability ratios of 1.2, 1.0, 0.67, and 0.11. Na+, Li+, and Cs+ were not measurably permeant, with permeabilities less than 0.05 that of K+. Currents with the various ions were typically less than expected on the basis of the permeability ratios, which suggests that the movement of an ion through the channel was not independent of the other ions present. For a fixed activity of Ko+ (77 mM), plots of single channel conductance vs. activity of Ki+ were described by a two-barrier model with a single saturable site. This observation, plus the finding that the permeability ratios of Rb+ and NH+4 to K+ did not change with ion concentration, is consistent with a channel that can contain a maximum of one ion at any time. The empirically determined dissociation constant for the single saturable site was 100 mM, and the maximum calculated conductance for symmetrical solutions of K+ was 640 pS. TEAi+ (tetraethylammonium ion) reduced single channel current amplitude in a voltage-dependent manner. This effect was accounted for by assuming voltage-dependent block by TEA+ (apparent dissociation constant of 60 mM at 0 mV) at a site located 26% of the distance across the membrane potential, starting at the inner side. TEAo+ was much more effective in reducing single channel currents, with an apparent dissociation constant of approximately 0.3 mM.

Preparation for Birth into an O2-Rich Environment: the Antioxidant Enzymes in the Developing Rabbit Lung

Abstract: To determine if some specific "preparation for birth" occurs in the developing lung to help assure its successful adaptation to a comparatively O2-rich world at birth, we measured the activities of the antioxidant enzymes in the developing lungs of rabbit fetuses from 10 d before parturition to several days after birth. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GP) activities showed similar maturational patterns with significant increases in activity, compared with earlier gestational levels, during the last 3-5 d before birth. During the final days in utero, SOD and CAT activities increased by approximately 110% and lung GP activity by approximately 200%. There were no parallel changes in lung O2 consumption demonstrable over this same prenatal period.

The cerebrohepatorenal (Zellweger) syndrome. Increased levels and impaired degradation of very-long-chain fatty acids and their use in prenatal diagnosis.

Abstract: The cerebrohepatorenal (Zellweger) syndrome is a fatal autosomal recessive disorder manifested in the neonatal period by profound hypotonia, psychomotor retardation, dysmorphic features, and an enlarged liver. In this study we demonstrate fivefold or greater increases of very-long-chain fatty acid levels, particularly hexacosanoic acid (C26:0) and hexacosenoic acid (C26:1), in plasma and cultured skin fibroblasts from 20 patients. Similar findings in cultured amniocytes from 3 of 14 women in whom the fetus was at risk of the Zellweger syndrome permitted prenatal diagnosis. Oxidation of very-long-chain fatty acids, which normally takes place in the peroxisome, was impaired in homogenates of cultured skin fibroblasts and amniocytes. This observation extends the evidence that the Zellweger syndrome belongs to the newly formulated category of peroxisomal disorders. The pattern of excess very-long-chain fatty acids differs from that demonstrated previously in patients with childhood adrenoleukodystrophy. The study of very-long-chain fatty acids provides a convenient method for the early diagnosis and prenatal detection of the Zellweger syndrome.

Pacifying Effects of Nonnutritive Sucking on Term and Preterm Neonates During Heelstick Procedures

Abstract: Behavioral state, heart rate, and respiration were monitored during heelstick procedures in samples of healthy, term neonates (N = 48) and preterm neonates treated in minimal care (N = 48) and intensive care (N = 48) nurseries The treated infants who were given pacifiers spent significantly less time fussing and crying during and following the heelstick procedures Physiologic arousal was monitored in both preterm groups but was attenuated only in the preterm infants who received pacifiers (minimal care group) As similar amounts of sucking were observed in both preterm groups, the inconsistency in treatment effects on behavioral and physiologic arousal was interpreted as a lack of cardiac-somatic coupling in the neonate in intensive care Results suggest that nonnutritive sucking during heelstick procedures may attenuate behavioral distress in all neonates and physiologic arousal in neonates with less severe postnatal complications

Cell‐Cycle Analysis Using A Monoclonal Antibody to Brdurd

Abstract: The flow cytometric measurement of DNA distributions of cells has many applications in biomedical research. Phase fractions estimated (calculated) from such distributions are used to study the growth characteristics of various types of cells, particularly when the cells have been exposed to perturbing agents such as chemotherapeutic drugs. For more than 10 years many methods for resolving DNA distributions into the three cell subpopulations (G1, S and G2 + M) have been reported in the literature. A new method of analysis utilizing a monoclonal antibody to bromodeoxyuridine (BrdUrd) has been developed (Gratzner, 1982; Dolbeare et al., 1983) which makes it possible in most cases to accurately determine phase fractions without resorting to mathematical models. The procedure involves the incorporation of BrdUrd by growing (DNA synthesizing) S phase cells, labelling the BrdUrd with a fluorescent monoclonal antibody, and the bivariate measurement of the antibody and of total DNA content, the latter through propidium-iodide staining. The resulting bivariate distributions clearly and simply resolve the three subpopulations. This paper describes the method and illustrates its use in the analysis of various fractions of elutriated exponentially growing Chinese hamster ovary (CHO) cells.

Capping and the Cytoskeleton

Abstract: Publisher Summary This chapter summarizes the results obtained in capping/cytoskeleton research. There are two types of capping phenomena: ligand-dependent and ligand-independent processes. A number of different reagents, such as colchicine and hypertonic media, can cause the formation of cap structures in the absence of any externally added ligand. Morphological studies, using both transmission and scanning electron microscopy, of cells forming caps in hypertonic medium have identified a strong association between cap structures and microvilli. External ligand (antibody, lectin, or some hormones) mediated receptor patching and capping is responsible for important immune-related responses: ( 1) proliferation and differentiation of the cells into antibody-secreting plasma cells, (2) the development of an increased number of precursor cells which are responsible for immunological memory, and (3) the activation and proliferation of T cells which carry out cell-mediated cytotoxic killing. In nonimmune cells, capping may also be involved in important cellular processes, such as endocytosis, chemotaxis, mitogenesis, and general cell–cell recognition.

Night synthesis of protein by algae1

Abstract: Dunaliella tertiolecta in culture showed rates of net protein synthesis at night nearly equal to those during the day. In night protein synthesis carbon stored in carbohydrates and metabolite pools was used, whereas sulfate was assimilated from the medium as needed. As a result, whole cell C:S ratios varied systematically over the diel cycle, while the C:S ratio of isolated protein remained constant. In the stationary phase, sulfate incorporation into protein, unlike carbon incorporation, measured net protein synthesis rather than turnover. Diel experiments with natural populations of marine and freshwater algae demonstrated that night protein synthesis is a general phenomenon in phytoplankton. For samples previously exposed to saturating light, day and night rates of protein synthesis were similar. The use of carbohydrate and metabolic pool carbon for night protein synthesis not only increased protein to the food web, but also altered ratios of protein, carbohydrate, and lipid to one another. The latter might result in changes in the nutritional value of phytoplankton to herbivores.

A decreased incidence of necrotizing enterocolitis after prenatal glucocorticoid therapy.

Abstract: In a large multicentered, collaborative randomized and blinded trial utilizing antenatal corticosteroids, the goals included determining the effectiveness of these agents in accelerating lung maturation, as well as monitoring any short-term or long-term adverse effects of this treatment on the parturient, fetus, and/or infant. More than 100 specific items, pertaining to diagnoses, complications, and outcomes were recorded for the 696 mothers enrolled in the study and their 745 infants. A significantly decreased incidence of necrotizing enterocolitis (P = .002) was found in the infants treated with steroids. The possibility of accelerated intestinal maturation induced by antenatal maternal steroid therapy exists. This treatment regimen is particularly attractive as adverse aspects of steroid therapy at the dosage utilized have not been demonstrated.

Alteration of the upper oceanic crust, DSDP site 417: mineralogy and chemistry

Abstract: Basalts from DSDP Site 417 (109 Ma) exhibit the effects of several stages of alteration reflecting the evolution of seawater-derived solution compositions and control by the structure and permeability of the crust. Characteristic secondary mineral assemblages occur in often superimposed alteration zones within individual basalt fragments. By combining bulk rock and single phase chemical analyses with detailed mineralogic and petrographic studies, chemical changes have been determined for most of the alteration stages identified in the basalts. 1) Minor amounts of saponite, chlorite, and pyrite formed locally in coarse grained portions of massive units, possibly at high temperatures during initial cooling of the basalts. No chemical changes could be determined for this stage. 2) Possible mixing of cooled hydrothermal fluids with seawater resulted in the formation of celadonite-nontronite and Fe-hydroxide-rich black halos around cracks and pillow rims. Gains of K, Rb, H2O, increase of Fe3+/FeT, and possibly some losses of Ca and Mg occurred during this stage. 3a) Extensive circulation of oxygenated seawater resulted in the formation of various smectites, K-feldspar, and Fe-hydroxides in brown and light grey alteration zones around formerly exposed surfaces. K, Rb, H2O, and occasionally P were added to the rocks, Fe3+/FeT increased, and Ca, Mg, Si and occasionally Al and Na were lost. 3b) Anoxic alteration occurred during reaction of basalt with seawater at low water-rock ratios, or with seawater that had previously reacted with basalt. Saponite-rich dark grey alteration zones formed which exhibit very little chemical change: generally only slight increases in Fe3+/FeT and H2O occurred. 4) Zeolites and calcite formed from seawater-derived fluids modified by previous reactions with basalt. Chemical changes involved increases of Ca, Na, H2O, and CO2 in the rocks. 5) A late stage of anoxic conditions resulted in the formation of minor amounts of Mn-calcites and secondary sulfides in previously oxidized rocks. No chemical changes were determined for this stage.

The neuropathology of acquired immune deficiency syndrome.

Abstract: We reviewed the neuropathologic characteristics of 52 cases of acquired immune deficiency syndrome (AIDS) at autopsy. Histologically significant neuropathologic lesions were found in 38 cases. We believed that infection was the predominant pathologic process in 26 cases; occasionally, multiple infectious agents were present. This included Toxoplasma encephalitis (n = 16), fungal abscess (n = 1), tuberculous abscess (n = 1), progressive multifocal leukoencephalopathy (n = 2), cysticercosis (n = 1), and Escherichia coli meningoencephalitis (n = 1). Microglial nodules or perivascular inflammation suggested that encephalitis was the most likely cause in five cases. In two additional cases, a primary demyelinating process that was apparently related to cytomegalovirus was present. Vascular or hypoxic diseases were present in nine cases. The findings included intracerebral hemorrhage (n = 1), subarachnoid hemorrhage (n = 2), infarction (n = 2), diffuse hypoxic changes (n = 5), cerebral edema (n = 1), and rare thromboemboli with extravasation of RBCs (n = 1). One case of primary lymphoma was observed. The CNS lesions were the proximate cause of death in 15 patients. The CNS complications of AIDS are varied and often are the major manifestation of the syndrome.

Neutral proteases capable of proteoglycan digesting activity in osteoarthritic and normal human articular cartilage

Abstract: Proteases have been postulated to account for the progressive disappearance of matrix proteoglycans in osteoarthritic (OA) cartilage. The digestion of endogenous proteoglycans by neutral proteases in human OA cartilage homogenates has been measured and compared with that of normal age-matched controls. Cartilage was obtained from 16 patients at the time of knee arthroplasty and from 7 accident victims. Tissue blocks were cut from the tibial plateau; part was used for histologic grading of the severity of OA and part was homogenized for the quantification of neutral metallo- and serine protease activities, based on the release of digested products from endogenous proteoglycans. Total metalloprotease activity (latent plus active forms) was elevated 3- to 10-fold in all diseased cartilage. This elevation was already significant in mild disease, but was greatest in samples of moderate to severe disease. The active form of the enzyme was highest at the center of erosions and decreased in the margins of the plateau. The digestion of proteoglycans, as distinct from their mere release from the tissue, was demonstrated by chromatography on Sepharose-CL2B and by large pore electrophoresis. Serine protease activity on proteoglycans was much lower than that of metalloprotease. The mean activity was highest in mild disease and declined in the severe disease samples, but the difference between these 2 groups and the controls was not statistically significant. The results of this study are consistent with the hypothesis that the neutral metalloproteases of cartilage are involved in the degradation of proteoglycans in osteoarthritis.

Reactive Surface Area of Skeletal Carbonates During Dissolution: Effect of Grain Size

Abstract: Major advances have recently been made in quantifying the chemical parameters which control carbonate mineral reaction kinetics in natural waters. One of the primary factors influencing rates of reaction is the amount of surface area per unit mass available for reaction. For relatively smooth, nonporous carbonates, the relationship between reactive and total surface area measured by gas adsorption has proven simple. However, the dominant carbonates in the marine environment are biogenic and exhibit complex microstructures. We have performed experiments to determine dinghy what proportion of the total surface area of these biogenic carbonates is actually available for reaction during dissolution. Three biogenic carbonates having widely differing microstructures (Halimeda, coral, and echinoid) were chosen for study and comparison with rhombic calcite. The influence of grain size on the relation between total surface area, determined from gas adsorption, and reactive surface area, determined relative to rhombic calcite during dissolution in constant composition solutions, was of primary concern. Unlike rhombic calcites, total surface area for texturally complex biogenic grains varied slightly or not at all with increasing grain size. However, both rhombic calcite and biogenic carbonate dissolution rates were inversely related to grain radius. This implies that much of the total surface area of biogenic carbonates is unavailable for reaction with the aqueous solution. Dissolution rates were a function of both grain size and microstructure. We have defined an empirical roughness factor which quantifies the difference in reactive surface area between rhombic calcite and a given biogenic grain of equivalent size. The roughness factor increased with grain microstructural complexity but was independent of grain size over the grain-size range (51-513 microns) studied. The maximum roughness factor value observed was 7 for Halimeda relative to a value of 1 for rhombic calcite. Our findings indicate that both microstructure and grain size can play important roles in controlling reactivity of biogenic carbonates during diagenesis. The relative significance of grain size versus microstructure for carbonate dissolution rates in natural systems is discus ed.

Cervical sagittal spinal canal size in spine injury.

Abstract: This study investigated the relationship between cervical spine sagittal canal diameter and neurologic injury in cases of spinal fracture-dislocation. A group of 98 patients with such injuries was reviewed; 45 had no neurologic deficits, 39 had incomplete quadriplegia, and 14 had complete quadripleg

Stable Coexistence States in the Volterra–Lotka Competition Model with Diffusion

Abstract: We study the existence, uniqueness, and stability of coexistence states in the Lotka–Volterra model with diffusion for two competing species. We assume that the parameters describing the interactio...