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Biomedical subjects

M Garrett

Publications and source records attributed to M Garrett.

At least 37 records · Page 2Linked to original sources
PubMed1996

Inhibition of nitric oxide with aminoguanidine reduces bacterial translocation after endotoxin challenge in vivo.

BACKGROUND: Administration of lipopolysaccharide (LPS) has been shown to increase bacterial translocation (BT) in vivo and in vitro. In addition, LPS upregulates inducible nitric oxide synthase expression in the intestinal epithelium-a phenomenon that can either enhance microbial killing, or alternatively, promote BT by impairing the gut barrier. OBJECTIVE: To determine the effect, if any, of an inhibitor of nitric oxide synthase, namely, aminoguanidine (AG), on BT after LPS challenge. DESIGN: Sprague-Dawley rats were randomized to receive either AG or normal saline solution via subcutaneously placed osmotic pumps (Alzet), followed 18 hours later by LPS injection (5 mg/kg or 20 mg/kg intraperitoneally). Quantitative cultures of the cecum, mesenteric lymph nodes, liver, and spleen were obtained, and plasma nitrite and nitrate levels were measured at 24 hours. Transmembrane potential difference and mucosal permeability to fluorescein isothiocyanate-labeled dextran and fluorescein isothiocyanate-labeled Escherichia coli C25 were measured in the Using chamber. The intestinal membrane was examined by light, transmission electron, and confocal laser microscopy. RESULTS: Rats that were given high-dose LPS had elevated levels of nitrite and nitrate and a 100% incidence of BT. In contrast, AG infusion significantly reduced both BT (22%) and nitrite and nitrate levels. Animals that received LPS and normal saline solution had a significantly lower transmembrane potential difference than those that received LPS and AG. High-dose LPS resulted in sloughing of the apical enterocytes at the villus tips where bacterial entry seemed to occur, as seen with confocal laser microscopy. CONCLUSIONS: Inhibition of nitric oxide production with AG decreases BT after high-dose LPS challenge. The mechanism may involve increased cellular viability and decreased damage to the gut mucosal barrier in rats that receive AG.

Animals↗
PubMed1996

The microenvironment influences the pattern of bacterial translocation in formula-fed neonates.

The authors previously demonstrated that neonatal rabbits fed conventional formula have a significantly greater incident of bacterial translocation than do neonatal rabbits fed breast milk. They hypothesized that exogenous bacteria in the formula and/or the microenvironment of the neonatal rabbit may contribute to the higher incidence of bacterial translocation. In the present study, the authors examined the incidence of bacterial translocation in neonatal rabbits fed pasteurized formula, unsterile formula, or breast milk while being housed in a clean or unsterile environment. The rabbits were divided into five groups. Groups I and II were fed pasteurized formula; groups III and IV were fed unsterile formula. In addition, groups I and III were housed in a clean environment, and groups II and IV were kept in an unsterile environment. The neonates in group V were fed breast milk and were kept in an unsterile environment. On the seventh day, the animals were killed, and the mesenteric lymph nodes, liver, and spleen were cultured for the presence of bacteria. Bacterial translocation occurred in 100% of group IV neonates. A clean environment (groups I and III) eliminated gram-negative bacterial translocation. A reduction (50%) in the overall incidence of bacterial translocation was obtained by pasteurizing the formula (group I v group III). Group II had significantly less gram-negative bacterial translocation than did group IV. None of the neonates in group V had translocation. The data show that a clean environment abrogates gram-negative bacterial translocation. Pasteurizing the formula significantly reduces the incidence of gram-negative bacterial translocation, and further reduces overall bacterial translocation in a clean environment. The authors hypothesize that control of the microenvironment can significantly influence the pattern of bacterial translocation in formula-fed neonates, and thus potentially reduce the incidence of gut-origin sepsis. Factors present in breast milk inhibit bacterial translocation, regardless of the microenvironment.

Animals↗
PubMed1996

Ultrastructural, immunohistological and biochemical characterization of cultured mouse corneal epithelial cells.

We developed a method to culture mouse corneal epithelium. Cultured cells tested by 1-D-SDS-PAGE exhibited protein mobility patterns similar to freshly isolated epithelia. Western blots with antibodies broadly recognizing cytokeratins showed a similar pattern for both fresh and cultured cells, but only the fresh sample stained with J7, specific for a 55-kD 'corneal' cytokeratin. Cultured cells examined at confluency by transmission electron microscopy exhibited desmosomal contacts typical of epithelia. The ability to culture mouse corneal epithelial tissue will be useful for studies requiring large amounts of material by reducing animal numbers.

Animals↗
PubMed1995

Self-recognition in primates: phylogeny and the salience of species-typical features.

Self-recognition has been explored in nonlinguistic organisms by recording whether individuals touch a dye-marked area on visually inaccessible parts of their face while looking in a mirror or inspect parts of their body while using the mirror's reflection. Only chimpanzees, gorillas, orangutans, and humans over the age of approximately 2 years consistently evidence self-directed mirror-guided behavior without experimenter training. To evaluate the inferred phylogenetic gap between hominoids and other animals, a modified dye-mark test was conducted with cotton-top tamarins (Saguinus oedipus), a New World monkey species. The white hair on the tamarins' head was color-dyed, thereby significantly altering a visually distinctive species-typical feature. Only individuals with dyed hair and prior mirror exposure touched their head while looking in the mirror. They looked longer in the mirror than controls, and some individuals used the mirror to observe visually inaccessible body parts. Prior failures to pass the mirror test may have been due to methodological problems, rather than to phylogenetic differences in the capacity for self-recognition. Specifically, an individual's sensitivity to experimentally modified parts of its body may depend crucially on the relative saliency of the modified part (e.g., face versus hair). Moreover, and in contrast to previous claims, we suggest that the mirror test may not be sufficient for assessing the concept of self or mental state attribution in nonlinguistic organisms.

Animals↗
PubMed1995

Classification of walking handicap in the stroke population.

BACKGROUND AND PURPOSE: The limited walking ability that follows a stroke restricts the patient's independent mobility about the home and community, a significant social handicap. To improve the in-hospital prediction of functional outcome, the relationships between impairment, disability, and handicap were assessed with clinical measures in 147 stroke patients. METHODS: The patients' level of functional walking ability at home and in the community was assigned by expert clinicians to one of the six categories of a modified Hoffer Functional Ambulation scale at least 3 months after discharge. A 19-item questionnaire was further used to assess current customary mobility of the subjects. Functional muscle strength and proprioception were tested, and walking velocity was measured. RESULTS: The significant indicators of impairment, upright motor control knee flexion and extension strength, differentiated household from community ambulators. The addition of velocity improved the functional prediction. Proprioception was clinically normal in all walkers. The validity of the criteria for the six levels of walking handicap was confirmed statistically. Stepwise discriminant analysis reduced the ambulation activities on the questionnaire from 19 to 7. Redefinition of the criteria for patient classification using the coefficients and constants of the seven critical functions improved the prediction of patient walking ability to 84%. CONCLUSIONS: The results of this study offer a quantitative method of relating the social disadvantage of stroke patients to the impairment and disability sustained. The measurement of therapeutic outcome in relation to the social advantage for the patient would allow more efficient standardization of treatment and services.

Activities of Daily Living↗
PubMed1993

The cycle of SEC4 function in vesicular transport.

Sec4 is a Ras-like GTP-binding protein required for exocytosis in yeast. Unlike Ras, it is the ability of Sec4 to cycle between the GTP- and GDP-bound forms rather than the absolute levels of the GTP-bound form that is critical for function. This cycle may be coupled to an observed cycle of Sec4 localization within the cell. Sec4 binds to secretory vesicles which then fuse with the plasma membrane in exocytosis. Sec4 can recycle from the plasma membrane through a soluble pool to rebind to a new round of vesicles. We have found an activity in yeast (Saccharomyces cerevisiae) comparable to that of the GDP dissociation inhibitor protein isolated from mammalian cells that releases GDP-bound Sec4 from membranes. DSS4-1, a dominant suppressor of the sec4-8 temperature-sensitive mutation, encodes a nucleotide exchange protein. The cycle of Sec4 may function to allow the assembly and subsequent disassembly of a set of proteins necessary for exocytosis. Candidates for members of this set of proteins are encoded by sec genes which show strong genetic interactions with sec4-8. Two of these (SEC8 and SEC15) encode large proteins which form a complex that is peripherally associated with the plasma membrane.

Biological Transport↗
PubMed1992

Disorders of lexical selection.

Errors in lexical processing are commonplace in language pathologies resulting from brain injury or disease. This discussion considers some of the major recent developments in the interpretation of such errors. The focus is on behavioral systems, rather than neuroanatomical or neurophysiological issues. The objective is to comment on some plausible mutual implications of generally attested pathologies and normal models of lexical retrieval for production, particularly with respect to the roles of semantic and syntactic categories.

Female↗
PubMed1992

Hydrolysis of GTP by Sec4 protein plays an important role in vesicular transport and is stimulated by a GTPase-activating protein in Saccharomyces cerevisiae.

Sec4, a GTP-binding protein of the ras superfamily, is required for exocytosis in the budding yeast Saccharomyces cerevisiae. To test the role of GTP hydrolysis in Sec4 function, we constructed a mutation, Q-79----L, analogous to the oncogenic mutation of Q-61----L in Ras, in a region of Sec4 predicted to interact with the phosphoryl group of GTP. The sec4-leu79 mutation lowers the intrinsic hydrolysis rate to unmeasurable levels. A component of a yeast lysate specifically stimulates the hydrolysis of GTP by Sec4, while the rate of hydrolysis of GTP by Sec4-Leu79 can be stimulated by this GAP activity to only 30% of the stimulated hydrolysis rate of the wild-type protein. The decreased rate of hydrolysis results in the accumulation of the Sec4-Leu79 protein in its GTP-bound form in an overproducing yeast strain. The sec4-leu79 allele can function as the sole copy of sec4 in yeast cells. However, it causes recessive, cold-sensitive growth, a slowing of invertase secretion, and accumulation of secretory vesicles and displays synthetic lethality with a subset of other secretory mutants, indicative of a partial loss of Sec4 function. While the level of Ras function reflects the absolute level of GTP-bound protein, our results suggest that the ability of Sec4 to cycle between its GTP and GDP bound forms is important for its function in vesicular transport, supporting a mechanism for Sec4 function which is distinct from that of the Ras protein.

Amino Acid Sequence↗
PubMed1992

Development and use of preprinted forms and adhesive labels in medical record charting.

Clear delineation of specific clinical and administrative responsibilities (eg, content requirements, cost constraints) is necessary in the development, approval, and implementation of effective preprinted documentation materials. Input early in the development stage from medical record and legal department staff ensures that proposed materials will meet organizational and legal standards. The development and use of time-saving preprinted documentation materials in medical record charting by the Johns Hopkins Oncology Nutrition Service is described. We conclude that the use of preprinted materials expedites and enhances both the consistency and quality of documentation.

Dietary Services↗
PubMed1991

Adult and fetal human mesangial cells interact with specific laminin domains.

Mesangial cells are centrally located pericytes in the renal glomerulus. They are surrounded by an extracellular matrix and directly contact the glomerular basement membrane in vivo. Because these interactions are critical for renal development and function, we have studied human mesangial cell interactions with laminin, a major adhesive component of basement membranes present in the extracellular matrix of the mesangium. Human fetal and adult mesangial cell attachment was stimulated by both laminin and the laminin-derived synthetic peptides YIGSR-NH2, CQAGTFALRGDNPQG-NH2, and CIKVAVS-NH2. Furthermore, mesangial cells spread on laminin as well as on both the RGD-containing and CIKVAVS peptides. When added in solution, all three peptides inhibited mesangial cell attachment to laminin, and the latter two peptides inhibited mesangial cell spreading on laminin. Laminin affinity column chromatography demonstrated several low-molecular-mass laminin-binding proteins ranging from between 35 and 42 kDa, which predominated in fetal mesangial cells, whereas a higher molecular mass laminin-binding protein of 65 kDa was predominant in adult mesangial cells. Western blot analysis with an anti-32-kDa laminin-binding protein antibody showed increased expression of both 31- and 42-kDa proteins in fetal mesangial cells when compared with the adult. The antisera to the 32-kDa laminin-binding protein also inhibited fetal mesangial spreading on the CIKVAVS peptide. Western blot analysis with an anti-67-kDa laminin-binding protein antibody revealed a 110-kDa protein in adult mesangial cells that was not present in fetal mesangial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Down-regulation of mannose receptor activity in macrophages after treatment with lipopolysaccharide and phorbol esters.

We have investigated the effects of LPS and PMA on the expression of functional mannose receptors in rat bone marrow-derived macrophages. After 48 h of treatment with LPS (10 ng/ml) and PMA (100 nM), mannose receptor activity was reduced by 70 to 80%. The effect of these agents on receptor activity was not reversible, and activity continued to decline after the agents were removed. Pretreatment of cells with dexamethasone was effective in blocking the LPS/PMA-induced down-regulation. Serine protease inhibitors did not block the reduction in receptor activity, suggesting that proteolysis is not involved in receptor down-regulation. LPS/PMA treatment did not increase turnover of the receptor. Ligand uptake studies showed that the total capacity of the uptake system was reduced by 80%, although the Kuptake was unaffected. Binding of 125I-mannose-BSA to intact macrophages showed a 70% decrease in surface receptor activity after treatment with LPS/PMA. LPS/PMA treatment had no effect on total receptor synthesis as quantitated by immunoprecipitation of metabolically labeled receptor. However, binding of metabolically labeled receptor to mannose-Sepharose, and binding of 125I-mannose-BSA to immunoprecipitated receptor revealed that intracellular plus surface binding sites were reduced to approximately 30% after LPS/PMA treatment. These results suggest that LPS/PMA treatment of macrophages results in an inactivation of mannose receptors with no effect on receptor turnover or biosynthesis.

Animals↗
PubMed1988

One hospital's solution to the shortage of coders.

The program described enabled St. Mary's Hospital to recruit individuals with pre-requisite knowledge in anatomy, pathophysiology and medical terminology and then have them receive comprehensive training in ICD-9-CM coding which addressed the unique demands imposed by the medical record department and the PRO. In this way, the department's immediate and future needs for coders appears to have been satisfied. An evaluation on the success of this training program will be assessed in three months and reported upon at that time.

Abstracting and Indexing↗
PubMed1987

Effect of chloroquine on intestinal lipid metabolism.

Most studies that have quantitated recovery of infused lipid in the intestinal mucosa and mesenteric lymph have only been able to recapture 50-75%. One possibility is that the missing lipid enters a triacylglycerol (TG) storage pool in the enterocyte and is hydrolyzed by lysosomal lipase, and the free fatty acid released is transported by the portal vein. This postulate was tested by comparing glyceryl trioleate (TO)-infused rats pretreated with the lysosomotropic drug, chloroquine (6.3 mg.kg-1.h-1) with saline controls. Chloroquine increased mucosal TG from 94 +/- 6 to 128 +/- 8 mumol. Additionally, the specific activity of the mucosal TG relative to the infused [3H]TO was reduced in the treated rats. The mucosal TG increase was not due to impaired TG output, which remained the same as controls. We conclude that the TG in the acid lipase-sensitive pool derives most of its glyceride-glycerol from endogenous sources. Furthermore, the increment in mucosal TG caused by chloroquine is not enough to explain the majority of the acyl groups unaccounted for in the mucosa and lymph after a TG infusion. For these a direct passage of acyl groups through the enterocyte is postulated.

Animals↗
PubMed1985

Grammatical class effects in relation to normal and aphasic sentence processing.

Agrammatic, Broca's aphasic patients, Wernicke's aphasic patients, and neurologically intact control subjects were asked to detect target letters in prose passages and in a scrambled word passage. The targets were embedded, in some instances, in content words (open-class vocabulary items), and in other instances, in function words (closed-class vocabulary items). With respect to the prose passages, both the control subjects and Wernicke's aphasic patients were more apt to notice target letters when they appeared in the open-class items than when in closed-class items; by contrast, the agrammatic Broca's patients showed no vocabulary class detection difference. The Wernicke's patients were not entirely normal, however: Whereas the normal subjects showed a much smaller vocabulary class effect for letter detection in the scrambled condition, the Wernicke's maintained the pattern they had shown in the prose condition. These and other findings obtained on the letter cancellation task are discussed in relation to lexical access mechanisms geared to sentence parsing.

Adult↗
PubMed1984

A mechanical device for leg disturbance during gait.

A method of applying a momentary mechanical stimulus to a human leg at any selected time during treadmill locomotion is described. The stimulus is produced by the breaking of a loop of fine copper wire by means of a motor and clutch device. An electrical signal at the time of stimulus is provided and the apparatus has no detrimental effect on normal walking.

Biomedical Engineering↗
PubMed1984

The pattern of osmotic regulation in larvae of the mosquito Culiseta inornata.

Larvae of Culiseta inornata (Williston) can survive and complete development in dilutions of sea water ranging from 50-700 mosmol kg-1. The larvae hyperregulate with regard to haemolymph osmotic concentration in dilute media (50-400 mosmol kg-1) and osmoconform when external salinities exceed 400 mosmol kg-1. This pattern of osmoregulation is distinct from that observed in freshwater and saline-water mosquito species. We propose that mosquitoes exhibiting this osmoregulatory pattern should be described as 'brackish-water' species. Larvae of Culiseta inornata are able closely to regulate both sodium and chloride ion concentrations in the haemolymph over the full range of salinities tested (50-750 mosmol kg-1). The Malpighian tubules produce an isosmotic, potassium-rich fluid. In vitro and in vivo sampling of rectal fluids demonstrates that rectal secretions are isosmotic or only slightly hyperosmotic to the haemolymph and the surrounding saline media, and that they are isotonic with regard to sodium.

Aedes↗