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L McCarthy

Publications and source records attributed to L McCarthy.

At least 37 records · Page 2Linked to original sources
PubMed1992

Simultaneous mobilization of Mac-1 (CD11b/CD18) and formyl peptide chemoattractant receptors in human neutrophils.

Mobilization of a distinct subset of specific granules provides a physiologically important mechanism to recruit Mac-1 (CD11b/CD18) from an intracellular pool to the external surface of the neutrophil plasma membrane, where the functionally active heterodimer mediates several adherence-dependent processes that are crucial for adequate host defense and cellular inflammatory responses. We observed similar characteristics for translocation of Mac-1 and neutrophil formyl peptide receptors (FPR) and hypothesize that the readily accessible pools of both Mac-1 and FPR are colocalized within this specific granule subset. Plasma membrane levels of both FPR (assessed with 3H-FMLP) and Mac-1 (assessed by fluorescence-activated cell sorter analysis of fluorescein isothiocyanate [FITC]-Mo-1-labeled cells) were markedly downregulated in cells prepared at low temperature from blood cooled to 4 degrees C immediately after removal from the circulation. Levels of both FPR and Mac-1 remained low on cells held at 4 degrees C. Upon warming, spontaneous upregulation of Mac-1 and FPR occurred with similar kinetics and temperature dependency. Translocation of both Mac-1 and FPR was markedly potentiated by exposure of cells to either fluoride ion (which has been shown by others to specifically elicit exocytosis of gelatinase-rich and vitamin B-12 binding protein-poor granules) or granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine that markedly potentiates the neutrophils' host defense capabilities. Levels of both FPR and Mac-1 on F-- or GM-CSF-treated neutrophils exceeded those present on cells incubated at 37 degrees C for extended time intervals, indicating that stimulated translocation may involve mobilization of an additional granule subset. Scatchard analysis showed that only low-affinity FPR were translocated during spontaneous and stimulus-dependent upregulation. To directly compare FPR levels on the surface of cells displaying varying levels of Mac-1 within a single cell suspension, cells were labeled with FITC-Mo-1 and sorted into subpopulations based on fluorescence intensity. After sorting, the individual populations were held at 4 degrees C to prevent further spontaneous upregulation, concentrated by centrifugation, and assayed for FPR levels. Under a variety of conditions, FPR levels correlated with Mac-1 (CD11b) expression on cell populations selected on the basis of CD11b fluorescence intensity. Analysis of subcellular fractions obtained from disrupted neutrophils before and after upregulation provided additional support for the hypothesis that Mac-1 and FPR are colocalized within a readily accessible subset of neutrophil granules.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Membrane↗
PubMed1992

Complete coverage of the Schizosaccharomyces pombe genome in yeast artificial chromosomes.

The genome of the fission yeast, Schizosaccharomyces pombe, consists of some 14 million base pairs of DNA contained in three chromosomes. On account of its excellent genetics we used it as a test system for a strategy designed to map mammalian chromosomes and genomes. Data obtained from hybridization fingerprinting established an ordered library of 1,248 yeast artificial chromosome clones with an average size of 535 kilobases. The clones fall into three contigs completely representing the three chromosomes of the organism. This work provides a high resolution physical and clone map of the genome, which has been related to available genetic and physical map information.

Base Composition↗
PubMed1992

Evaluation of culture and the Gen-Probe PACE 2 assay for detection of Neisseria gonorrhoeae and Chlamydia trachomatis in endocervical specimens transported to a state health laboratory.

The Gen-Probe PACE 2 assay (Gen-Probe Inc., San Diego, Calif.) was compared with culture for the detection of Neisseria gonorrhoeae in endocervical specimens that were mailed to the laboratory. During mail transport, the specimens were exposed to extremes of hot and cold weather for several days before arriving in the laboratory. Specimens on culture plates deteriorated during transport, as evidenced by many dead gonococcus-like colonies. The manufacturer's recommendation for reporting PACE 2 assay-positive results was modified to create a suspicious category for samples with relative light units near the positive cutoff value. Of a total of 4,869 specimens tested, 30 were positive by both methods and 102 were positive only by the PACE 2 assay. These additional 102 positive specimens were likely to be true positives, as indicated by several lines of indirect evidence, including detailed probe competition analysis, patient history, and the lack of false-positive results in hand-delivered specimens. Although Gen-Probe Inc. indicates that specimens are stable for up to 7 days, N. gonorrhoeae was easily detectable by the PACE 2 assay after 1 month of incubation at room temperature in the PACE 2 transport buffer. We also compared the Gen-Probe PACE 2 assay for Chlamydia trachomatis with culture on endocervical specimens delivered by same-day courier. Of 398 endocervical specimens tested, the PACE 2 assay detected 19 of 20 culture-positive samples. Although the assay failed to detect one culture-positive sample, it was able to detect two very weak culture-suspicious samples. Finally, PACE 2 assays for N. gonorrhoeae and C. trachomatis performed on the same samples indicated that the coinfection rate was 40% for women attending five family planning clinics. We concluded that the Gen-Probe PACE 2 assay system should be considered for use in testing those specimens that are transported to the laboratory through the mail.

Cervix Uteri↗
PubMed1988

Thyroid hormone control of preganglionic innervation of the adrenal medulla and chromaffin cell development in the rat. An ultrastructural, morphometric and biochemical evaluation.

In the rat, functional connections between the splanchnic nerve and the adrenal medulla are immature at birth and do not become fully competent until the first postnatal week. Neonatal administration of triiodothyronine (T3) accelerates this process, and the present study was undertaken to elucidate the underlying mechanisms. Rats were given T3 (0.1 mg/kg, s.c.) daily for 9 days beginning 1 day after birth. Preganglionic innervation of the adrenal medulla was examined by retrograde axonal transport of horseradish peroxidase (HRP). At 10 days of age, there was an increased number of labeled perikarya in the spinal cord of the hyperthyroid pups. Ultrastructural examination revealed a corresponding increase in synaptic density in the adrenal medulla and in the activity of choline acetyltransferase, a marker for preganglionic cholinergic nerve terminals. These effects were attenuated by 25 days of age, whereupon deficits in HRP-labeled neurons and adrenomedullary synapses were noted. Similarly, replication of chromaffin cells was enhanced transiently in the T3 group during the initial stage of hyperthyroidism, but subsequent long-lasting deficits in cell numbers were noted, along with a corresponding retardation of ontogeny of adrenal catecholamine biosynthesis and storage. Thus, neonatal hyperthyroidism accelerates synaptic development in the sympatho-adrenal axis but suppresses maturation of the target chromaffin cells, ultimately leading to impaired adrenomedullary function.

Adrenal Medulla↗
PubMed1988

Preadmission screening: an efficacy study.

The effectiveness of hospital social work preadmission screening and assessment is compared with postadmission screening and assessment. Outcome variables include length of stay, readmission rates, posthospital home management, resource attainment, and satisfaction with hospital services. The patients screened postadmission were assessed within forty-eight hours of admission, while the patients screened preadmission were assessed one to two weeks prior to admission. Telephone follow-up was conducted with both groups. Preadmission patients reported better home management and attained more resources. Patients' satisfaction with hospital care was inversely related to the need for more resources in the post-hospital period.

Aged↗
PubMed1986

Effects of insulin, adenosine, and prostaglandin on alpha-adrenergic-stimulated respiration in brown adipocytes.

The present study compared the effects of insulin, 2-chloroadenosine, and prostaglandin E2 as inhibitors of respiration in hamster brown adipocytes stimulated with either isoproterenol or phenylephrine. Addition of 2-chloroadenosine or prostaglandin E2 strongly antagonized isoproterenol-stimulated respiration; phenylephrine-stimulated respiration was also partially inhibited by 2-chloroadenosine and prostaglandin E2, but the extent of inhibition caused by these agents was not as great as when isoproterenol was used. Isoproterenol-stimulated respiration was inhibited by insulin, but phenylephrine-stimulated respiration was insensitive to the inhibitory effect of insulin. When brown adipocytes were pretreated with pertussis toxin, isoproterenol-stimulated respiration was enhanced, but phenylephrine-stimulated respiration was not significantly affected. The inhibitory effects of 2-chloroadenosine and prostaglandin E2 on isoproterenol-stimulated respiration were completely blocked by pertussis toxin, indicating that the mode of action of these inhibitory hormones was secondary to inhibition of adenylate cyclase and resultant inhibition of lipolysis. Prostaglandin E2 inhibition of phenylephrine-stimulated respiration was also abolished by pertussis toxin. In contrast, 2-chloroadenosine inhibition of phenylephrine-stimulated respiration persisted in adipocytes treated with pertussis toxin. These data suggest that phenylephrine stimulates respiration through a mechanism that is not altered by pertussis toxin and further that 2-chloroadenosine inhibition of isoproterenol- or phenylephrine-stimulated respiration can be dissociated.

2-Chloroadenosine↗
PubMed1985

Effects of pertussis toxin treatment on metabolism in hamster brown adipocytes.

This communication reports the effects of the exotoxin of Bordetella pertussis (pertussis toxin) on hamster brown fat cells. Pertussis toxin significantly increased the lipolytic and respiratory responses to isoproterenol but did not increase the basal rates of either of these processes. In contrast, the stimulation of respiration by the alpha-adrenergic agent phenylephrine was not altered by pertussis toxin. The inhibitory effects of adenosine on stimulated lipolysis, respiration, and adenylate cyclase activity were completely abolished by pertussis toxin, as was the ability of methylxanthines or adenosine deaminase to potentiate isoproterenol stimulation of respiration or lipolysis. These effects of pertussis toxin were associated with an ADP ribosylation of a single membrane protein having a molecular weight of approximately 41. These data demonstrate that pertussis toxin can prevent the inhibitory action of adenosine on brown fat cells and suggest that the effects of the nucleoside on these cells results from inhibition of adenylate cyclase. We further suggest that the enhanced responses to isoproterenol in pertussis-treated adipocytes results from a blockade of the action of endogenous adenosine. In addition to blocking adenosine action, pertussis toxin also abolished the antilipolytic effect of insulin. However, because the antilipolytic effect of insulin was prevented by adenosine deaminase and 3-isobutyl-1-methylxanthine and restored by 2-chloroadenosine, we conclude that insulin action on these cells is dependent on adenosine. Thus pertussis toxin blockade of insulin action appears to be secondary to blockade of adenosine action.

1-Methyl-3-isobutylxanthine↗
PubMed1985

cAMP metabolism and lipolysis in brown adipocytes of hamsters consuming a cafeteria diet.

Feeding animals cafeteria diets causes increased sympathetic activity to brown adipose tissue and this is believed to be responsible for the concomitant activation of thermogenesis. Because chronic catecholamine stimulation in other systems leads to a desensitization of beta-adrenergic receptors, we examined lipolysis and cAMP production in brown adipocytes of hamsters eating cafeteria diets for evidence of diminished beta-adrenergic responses. Basal cAMP levels were similar in chow- and cafeteria-fed hamsters. However, adipocytes from overfed animals formed less cAMP in response to isoproterenol than those of control animals. Isoproterenol-stimulated adenylate cyclase activity was similarly decreased in membrane preparations from cafeteria-fed hamsters. However, when the diterpene forskolin was used, equal amounts of cAMP were formed in cells and membrane preparations from control and overfed animals. In contrast to the reduced responses of the cAMP system to isoproterenol stimulation observed in overfed hamsters, isoproterenol-stimulated lipolysis was greater in cells from overfed animals than in cells from control animals. These results are consistent with a desensitization of the adenylate cyclase system in brown adipocytes occurring during chronic hyperphagia. Because eating cafeteria diets has been reported to increase sympathetic activity to brown fat depots, the apparent desensitization of brown adipocytes observed in this study may result from a persistent stimulation of the brown fat with norepinephrine in vivo. Our data also suggest the existence of mechanisms that preserve lipolysis in the face of low cAMP levels.

Adenylyl Cyclases↗
PubMed1985

Brown adipose tissue in cafeteria-fed hamsters.

Hamsters consuming a "cafeteria diet" had more brown adipose tissue than did chow-fed hamsters. The growth of the brown fat depots in cafeteria-fed hamsters was accompanied by increases in tissue protein and cytochrome oxidase. To assess the thermogenic capacity of brown fat mitochondria, the binding of GDP to isolated mitochondria was measured. Mitochondrial GDP binding was not affected by feeding the cafeteria diet for 4 wk, but more prolonged cafeteria feeding for 8 wk did, however, increase the binding of GDP to isolated mitochondria. The morphology of brown adipose tissue was altered during cafeteria feeding. The brown adipose tissue of cafeteria-fed hamsters had more large unilocular cells than did the brown adipose tissue of chow-fed hamsters. In addition, the average adipocyte diameter was greater in brown adipose tissue of cafeteria-fed hamsters. These data support the presence of a dietary regulation of brown adipose tissue growth in hamsters. The growth of brown adipose tissue in hamsters eating the cafeteria diet appears to result largely from proliferation of adipocytes, as evidenced by the increases in tissue protein and cytochrome oxidase during cafeteria feeding, but some hypertrophy of the adipocytes also occurs. A dietary regulation of brown fat thermogenic capacity is also apparent but this regulation is evident only after more prolonged periods of cafeteria feeding. Hamsters eating a cafeteria diet increase their caloric intake but have the same or greater body weight gain efficiency as do chow-fed animals. The absence of dietary stimulation of thermogenesis may underlie the similar efficiencies of weight gain in chow- and cafeteria-fed hamsters.

Adipose Tissue, Brown↗
PubMed1985

Computer detection of atrioventricular dissociation from surface electrocardiograms during wide QRS complex tachycardias.

Differentiation of wide QRS complex tachycardias on surface electrocardiograms is difficult for physicians and computers due in part to their inability to identify atrial activity, specifically atrioventricular (AV) dissociation. We studied 20 examples of AV associated rhythms and 17 examples of AV dissociated ventricular tachycardia. We applied an algorithm consisting of subtraction of a mean beat from each individual beat in leads II and V1 to generate remainder electrocardiograms. The remainder electrocardiograms were visually inspected for the presence of P wave candidates and then autocorrelated. AV dissociated P wave candidates were evident on visual inspection of remainder electrocardiograms in none of 20 AV associated and 15 of 17 AV dissociated rhythms. Atrial cycle length and the presence of AV dissociation were automatically detected by applying a peak selection algorithm to the autocorrelation function. AV association was detected in all 20 AV associated rhythms and AV dissociation was detected for 11 of 17 AV dissociated rhythms (sensitivity 65%, specificity 100%, positive and negative predictive accuracy 100%, 77%). The correlation coefficient of detected vs true atrial cycle length for the 11 correctly detected AV dissociated rhythms was r = .98. Visual inspection of the remainder electrocardiograms along with the original electrocardiogram may increase the ease with which human readers can identify the presence of AV dissociation and thus diagnose ventricular tachycardia. Computer diagnosis of wide QRS complex tachycardias should be significantly improved by use of this algorithm.

Atrioventricular Node↗
PubMed1984

Role of adenosine as an endogenous regulator of respiration in hamster brown adipocytes.

The action of endogeneous adenosine on isolated hamster brown adipocytes was examined. Adenosine production from brown adipocytes was measured after labeling of the intracellular nucleotide pool with [3H]adenine. Accumulation of [3H]adenosine in the incubation medium was maximum after 5 min of incubation and was still present after 20 min. When adenosine accumulation was prevented by addition of adenosine deaminase, the stimulatory effects of isoproterenol on oxygen uptake, lipolysis, and adenosine 3',5'-cyclic monophosphate (cAMP) generation were enhanced. However, basal rates of lipolysis and oxygen consumption and levels of cAMP were not affected on addition of adenosine deaminase. A similar potentiation of isoproterenol responses was produced by the adenosine receptor antagonist, 3-isobutyl-1-methylxanthine, present at a concentration (10 microM) which did not change basal levels of respiration or lipolysis. Addition of the adenosine analogue 2-chloroadenosine antagonized isoproterenol-stimulated respiration and lipolysis and prevented potentiation of isoproterenol responses with 3-isobutyl-1-methylxanthine. To localize the site of adenosine action, activity of adenylate cyclase in membrane preparations from brown adipocytes was measured. Isoproterenol-stimulated adenylate cyclase activity was partially inhibited by 2-chloroadenosine in a GTP-dependent manner. Addition of Na+ enhanced the inhibitory effect of 2-chloroadenosine, and 3-isobutyl-1-methylxanthine blocked it. The calculated 50% effective dose for 2-chloroadenosine inhibition was between 10 and 15 nM. These data suggest that adenosine produced by brown adipocytes is an endogenous regulator of respiration in these cells acting at the level of the adenylate cyclase enzyme.

1-Methyl-3-isobutylxanthine↗
PubMed1983

Alpha 1-adrenergic stimulation of hamster brown adipocyte respiration.

Respiration was increased approximately 5-fold with 0.05 microM norepinephrine and to a maximum of 10-fold by 0.30 microM norepinephrine. Prazosin, an alpha-adrenergic blocking agent highly selective for alpha 1-type receptors, partially inhibited the response to norepinephrine (0.05 microM) by 20-25% at a concentration of 0.10-1 microM. In contrast, when the stimulus for respiration was provided by isoproterenol or 3-isobutyl-1-methylxanthine, prazosin was without effect up to a concentration of 10 microM. Yohimbine, an alpha-adrenergic blocking drug preferential for alpha 2-receptors, did not influence norepinephrine-stimulated oxygen uptake. Respiration was increased two- to fourfold by phenylephrine or methoxamine, agents preferential for alpha 1-adrenergic receptors but not at all by clonidine, an agent preferential for alpha 2-adrenergic receptors. The stimulatory effect of phenylephrine on oxygen uptake was fully blocked by prazosin but not propranolol. Removal of extracellular calcium with ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid prevented phenylephrine stimulation of respiration but was without effect when isoproterenol was the stimulus. These results support the participation of alpha 1-adrenergic receptors in control of respiration and are consistent with the possibility that changes in cell calcium are intimately involved in this response.

1-Methyl-3-isobutylxanthine↗