Biomedical subjects

C K Kim

Publications and source records attributed to C K Kim.

At least 127 records · Page 7Linked to original sources

PubMed1999

Corneal topography of small-beam tracking excimer laser photorefractive keratectomy.

PURPOSE: To evaluate the topographic characteristic of photorefractive keratectomy (PRK) for low myopia performed with a small-beam (0.9 mm) tracking excimer laser. SETTING: Department of Ophthalmology, LSU Eye Center, Louisiana State University Medical Center School of Medicine in New Orleans, and the Refractive Surgery Center of the South at the Eye, Ear, Nose, & Throat Hospital, New Orleans, Louisiana, USA. METHODS: Sixty-seven eyes of 47 patients had PRK with a small-beam tracking laser. Of these, 49 eyes had data permitting evaluation of ablation centration; usable data for topographic analysis were available for 59 eyes preoperatively, 54 eyes at 1 month, 42 eyes at 3 months, and 25 eyes at 6 months, permitting measurement of various topographic parameters, including the cylinder (CYL), average corneal power (ACP), surface regularity index (SRI), surface asymmetry index (SAI), corneal eccentricity index (CEI), and coefficient of variation of corneal power (CVP). RESULTS: Preoperatively, all eyes were topographically normal. Postoperatively, no eye exhibited a "central island" by even the least-restrictive definition, and all eyes had best spectacle-corrected visual acuities (BSCVAs) of 20/20 or better at all follow-ups. Mean decentration of the ablations from the pupil centers was 0.42 mm +/- 0.28 (SD) (n = 49). There was no correlation between measured decentration and BSCVA (P = .46). The central cornea was flattened (decreased ACP; P < .001) and made oblate (decreased CEI; P < .001) as expected. There was no increase in SRI or SAI (irregular astigmatism) at 6 months compared with preoperative values (P = .91); however, CYL and CVP (varifocality) increased slightly (P = .04 and .02, respectively). CONCLUSION: The absence of significant regular or irregular astigmatism 6 months after PRK with the small-beam laser is an improvement over published results achieved with wide-beam lasers and is consistent with the excellent visual acuity results in this cohort.

Cornea↗

PubMed1999

Dose assessment and behavior of tritium in environmental samples around Wolsong nuclear power plant.

For the estimation of the dispersion trend of tritium discharged from the Wolsung nuclear power plant, the present level of tritium in environmental samples in the vicinity of the Wolsong site has been studied. On the basis of tritium concentrations in environmental samples, the effective dose due to tritium has been estimated for an individual and population within a 16 km radius from the Wolsong site. The annual effective dose of tritium to an inhabitant around the Wolsong site ranged from 0.15 microSv y-1 to 1.3 microSv y-1. The dose level was negligible and much lower than some applicable standards, i.e. the limit on exposure from nuclear fuel cycle to the general public as recommended by ICRP (1 mSv y-1) or US EPA's limit (0.25 mSv y-1). The collective dose to the total population within a 16 km radius from the site, 1.2 x 10(-2) man.Sv y-1 was much lower than 1 man.Sv y-1, an applicable criterion for the so-called "exemption" of radiation sources and practices from regulatory control.

Environmental Monitoring↗

PubMed1999

Development of wheezing in patients with cough variant asthma during an increase in airway responsiveness.

Two theories explaining the mechanism for the manifestation of cough without wheeze in patients with cough variant asthma (CVA) are either a higher wheezing threshold or a milder degree of airway hyperresponsiveness. A significant proportion of patients diagnosed as having CVA eventually develop wheezing. The aim of this study was to investigate whether this change in the manifestation of asthma was associated with a decrease in wheezing threshold and/or an increase in airway hyperresponsiveness. Thirty-six children (7-15 yrs) with CVA were prospectively studied for 4 yrs. Bronchial provocation tests with methacholine using the stepwise increasing concentration technique were performed annually to measure the provocative cumulative dose producing a 20% fall in forced expiratory volume in one second (PD20). Wheezing thresholds were additionally determined at the initiation of and the end of the study (development of wheezing, or after 4 yrs). Sixteen (Group 1) of 29 patients available for the follow-up developed clinical wheezing during the period; 13 patients (Group 2) stayed as CVA or their cough resolved. There was no significant change in wheezing thresholds from the initiation to the end of the study (Group 1: 40.9+/-8.2% versus 40.2+/-8.3%; Group 2: 41.4+/-7.1% versus 40.1+/-7.3%). Methacholine PD20 (geometric mean, range of 1 SD), expressed as breath unit (BU), significantly decreased in Group 1 patients as they developed wheezing (initial versus wheezing year: 60.8 BU, 29.2-126.5 versus 32.8 BU, 11.5-93.3; p<0.01), whereas the value did not change in Group 2 patients (initial versus after 4 yrs: 85.3 BU, 45.2-161.1 versus 84.3 BU, 39.7-179.1; NS). The results suggest that an increase in airway hyperresponsiveness, but not a decrease in wheezing threshold, may have a pathogenetic role in the development of wheezing during the course of cough variant asthma in childhood.

Adolescent↗

PubMed1999

Radioaerosol scintigraphy in infants and children born to mothers with HIV disease. Pediatric Pulmonary and Cardiovascular Complications (of Vertically Transmitted Human Immunodeficiency Virus) Study Group.

PURPOSE: To determine the usefulness of technetium 99m diethyltriaminepentacetic acid (DTPA) radioaerosol inhalation-clearance scintigraphy for early detection of pulmonary complications of human immunodeficiency virus (HIV) disease in children. MATERIALS AND METHODS: A total of 301 studies were performed in 132 HIV-positive children (group 1; mean age, 46.6 months). In children born to HIV-positive mothers (group 2), 273 studies were performed in 160 children who eventually were proved to be HIV negative (mean age, 10.3 months), and 80 studies were performed in 47 HIV-positive children (mean age, 15.6 months). Radioaerosol studies were performed by using commercially available radioaerosol nebulizers. Pulmonary clearance half-time was measured by using conventional gamma camera computer systems. Radioaerosol results were correlated with indexes of pulmonary health and function. RESULTS: The HIV-negative, group 2 children had a mean radioaerosol clearance half-time (58.1 minutes; 162 studies in 108 children) similar to that reported in healthy adults. Group 1 children with pulmonary involvement exhibited a faster mean clearance half-time (28.6 minutes) than did children without evidence of pulmonary involvement from either group 1 or group 2 (P < .05). A faster pulmonary clearance rate did not simply reflect the presence of chest disease that also was detectable on radiographs (P = .3). CONCLUSION: Quantitative DTPA radioaerosol clearance studies may provide useful information about pulmonary involvement in selected children with HIV disease.

Administration, Inhalation↗

PubMed1999

Administration-time differences in the pharmacokinetics of gentamicin intravenously delivered to human beings.

Administration-time differences of gentamicin pharmacokinetics were studied by crossover design after a single intravenous administration of gentamicin (80 mg) to 10 human subjects at 09:00 (morning time) and 22:00 (nighttime). The profiles of serum gentamicin concentration showed a significant statistical difference between 09:00 and 22:00, suggesting circadian variations of pharmacokinetic behaviors. A significant circadian rhythm of pharmacokinetic parameters as a function of time of day was noted in human subjects, showing lower total body clearance Clt and higher serum area under the curve (AUC) when given at nighttime. The half-life t1/2 was shorter in the morning (2.82 h +/- 0.43 h) when compared to the nighttime (2.97 h +/- 0.36 h), but the difference was not statistically significant. The AUC was significantly greater in the morning (23.4 +/- 3.84 micrograms-h/mL) than that in the nighttime (26.3 +/- 5.79 micrograms-h/mL) (p < .05), most likely because the Clt was significantly higher when gentamicin was given in the morning (3.51 +/- 0.57 L/h) versus in the nighttime (3.18 +/- 0.65 L/h). Although the volume of distribution Vd decreased when given at nighttime, it was independent of the dosing time. From this study, there was an administration-time difference of gentamicin pharmacokinetics in human beings. The optimized dosing regimen of gentamicin can be decided by considering circadian rhythm and rest-activity routine so that minimized toxicity and effective therapy are established for patients. The current findings also can be applied to other drugs with circadian rhythms of pharmacokinetics and narrow therapeutic windows in clinical chronotherapeutics.

Adult↗

PubMed1999

Relationship of CagA to serum gastrin concentrations and antral G, D cell densities in Helicobacter pylori infection.

The purpose of this study was to investigate whether the densities of antral gastrin and somatostatin-immunoreactive cells in Helicobacter pylori (H. pylori) infection were related to the bacterial expression of cytotoxin-associated gene A (CagA). 32 patients who had underwent diagnostic esophagogastroduodenoscopy were studied. On the histologic examination all patients had antral gastritis. We divided the subjects into three groups. Group I consisted of 6 patients who had chronic superficial gastritis, group II, 9 patients who had H. pylori-associated gastritis but with no expression of CagA, and group III, 17 patients who had H. pylori-associated gastritis with the expression of CagA. In group I and II, serum gastrin levels, and antral G cell and D-cell were measured. In group III, serum gastrin levels, and antral G cell and D-cell were measured, before and after the eradication of H. pylori. The results were as follows. Firstly, serum gastrin concentrations were significantly higher in the patients with H. pylori infection than in the negative controls. Nextly, there was no correlation between the changes in antral G or D-cell density and H. pylori infection. Thirdly, group III had a significant increase in serum gastrin concentrations and a significant decrease in antral D-cell density than group I. Forthly, eradication of H. pylori in group III showed a significantly increased antral D-cell density. Our results suggest that hypergastrinemia in H. pylori-associated gastritis is relevant to the presence of CagA, and the possible mechanism of hypergastrinemia may be related to antral D-cell deficiency, which is caused by H. pylori infection with the expression of CagA.

Adult↗

PubMed1999

Effects of prenatal exposure to alcohol on the release of adenocorticotropic hormone, corticosterone, and proinflammatory cytokines.

Prenatal alcohol exposure has been shown to produce hyperresponsiveness of the hypothalamic-pituitary-adrenal (HPA) axis to immune challenges. Because cytokines, which are released in response to immune challenges, are known to activate the HPA axis, this study determined whether altered release of cytokines contribute to the HPA hyperresponsiveness to immune challenges observed after prenatal alcohol exposure. Pregnant dams were exposed to alcohol vapors (6-7 hr daily) between days 7 and 18 of gestation. At postnatal days 45 and 60, control (C) and prenatal alcohol-exposed (E) offspring were subjected to three different types of immune challenges: injections of interleukin-1beta or endotoxin (lipopolysaccharide), or turpentine-induced tissue injury. We observed the expected higher plasma adrenocorticotropic hormone and corticosterone levels in E compared with C rats, and this HPA hyperresponsiveness was greater in E females compared with E males. Plasma tumor necrosis factor-alpha or interleukin-6 responses were comparable in the C and E groups. Females exhibited significantly higher corticosterone, tumor necrosis factor-alpha, and interleukin-6 responses than males. These results indicate that (1) prenatal alcohol exposure produces HPA hyperresponsiveness to immune challenges; (2) prenatal alcohol treatment does not influence the release of cytokines to immune challenges; and (3) there are gender differences in the secretory pattern of corticosterone and cytokines to immune challenges. Therefore, these data do not support the hypothesis that cytokines play a role in the hyperresponsiveness of the HPA axis to immune challenges observed after prenatal alcohol exposure.

Adrenocorticotropic Hormone↗

PubMed1999

Effects of prenatal ethanol exposure on hypothalamic-pituitary-adrenal responses to chronic cold stress in rats.

Animals prenatally exposed to ethanol typically exhibit hypothalamic-pituitary-adrenal (HPA) hyperresponsiveness to stressors. In contrast to previous studies that have investigated effects of prenatal ethanol exposure on HPA responses to acute or intermittent stressors, our study investigated HPA responses to a chronic continuous stressor, cold stress (4 degrees C for 0, 1, or 3 days). We tested the hypothesis that prenatal ethanol exposure would result in increased plasma corticosterone (CORT) and adrenocorticotropin (ACTH) responses and increased peptide [corticotropin-releasing factor and vasopressin] mRNA levels in the paraventricular nucleus (PVN) of the hypothalamus compared to that in control animals. In addition, CORT and ACTH responses were measured after exposure to an acute stressor (i.p. isotonic saline injection), superimposed during chronic cold exposure, to examine possible sensitization of the HPA response to the acute stress. Thus, blood samples were collected at the end of each of the three periods of cold exposure, either before (0 min) or 15 min after acute stress. The subjects were adult male and female Sprague-Dawley rat offspring from prenatal ethanol (E), pair-fed (PF), and ad libitum-fed control (C) treatment groups. Exposure to cold stress resulted in significant body weight loss in E males at 1 day and in both males and females of all prenatal treatment groups by 3 days of cold stress. Males in all prenatal groups also exhibited significant increases in adrenal weight:body weight ratios. Cold stress alone (0 min condition) increased CORT levels in E males and overall ACTH levels in E males and females compared to controls. ACTH levels were also higher overall in E compared to control males after acute stress (15 min condition). Sensitization of the CORT response to acute stress was observed in males but not females across all prenatal treatment groups. Corticotropin-releasing factor and vasopressin mRNA levels in the PVN were not significantly affected by prenatal treatment or chronic cold stress in either males or females. In contrast, both males and females displayed increases in PVN thyrotropin-releasing hormone (TRH) mRNA levels after cold stress. These data support and extend previous work demonstrating differential effects of prenatal ethanol exposure on HPA responsiveness of male and female offspring, and suggest that E males may be more vulnerable to the effects of chronic cold stress than E females.

Adrenocorticotropic Hormone↗

PubMed1998

Structure of catechol 2,3-dioxygenase gene from Alcaligenes eutrophus 335.

Catechol 2,3-dioxygenase (C23O), one of extradiol-type dioxygenases cleaving aromatic C-C bond at meta position of dihydroxylated aromatic substrates, catalyzes the conversion of catechol to 2-hydroxymuconic semialdehyde. As our ongoing study to characterize biochemical and genetic properties of the extradiol-type dioxygenases at molecular level, a C23O gene encoded in chromosomal DNA of Alcaligenes eutrophus 335, a strain degrading phenol and p-cresol, was cloned. The C23O gene was localized in an 1.4-kb PstI fragment from A. eutrophus 335, and was expressed in E. coli HB101. The C23O exhibited the highest aromatic ring-fission activity to catechol as a substrate, and its relative activity to other dihydroxylated aromatic substrates was in order of catechol >> 4-methylcatechol > 3-methylcatechol, protocatechuate, 4-chlorocatechol > 3,4-dihydroxy-phenylacetate > 2,3-dihydroxybiphenyl. Nucleotide sequence of the 1.4-kb fragment has revealed that an open reading frame (ORF) corresponding to the C23O gene was composed of 930 base pairs. A putative ribosome-binding sequence of AGGAG was found at about 10 nucleotides upstream the ORF which can encode a polypeptide of molecular weight 34 kDa consisting of 309 amino acid residues. The deduced amino acid sequence of C23O from A. eutrophus 335 exhibited the highest 59% identity with those of corresponding enzymes from Pseudomonas sp. CF600 (p VI150), P. putida HS1 (pDK1), and P. putida PpG7 (NAH7). An alignment of amino acid sequences of extradiol-type dioxygenases including C23O from A. eutrophus 335 has revealed that catalytically and structurally important amino acid residues of the enzymes were conserved during evolution.

Alcaligenes↗

PubMed1998

Analysis of the envelope region of hepatitis G virus isolated from Korean patients.

The genetic diversity of hepatitis G virus (HGV) was investigated. By using a RT-PCR procedure, 14% of either HBV (hepatitis B virus)- or HCV (hepatitis C virus)-positive Korean hepatitis patients were proved to be HGV positives. Nucleotide sequences in the E1 region of the eight isolates from Korean patients and the six previously reported isolates were compared. Nucleotide substitutions spread uniformly throughout the E1 region. Sequence homology among the Korean isolates was 84-99% and 88-99% at the nucleotide and amino acid sequences, respectively, whereas those from different geographic areas was slightly lower at both levels. At least two genotypes might exist among the Korean HGV isolates. Compared to the corresponding region of HCV, the E1 sequence from HGV is moderately conserved. In addition, as frameshift mutations were observed in most of the Korean isolates compared to the prototype HGV sequence, the Korean isolates might not use the translational initiation site of the prototype HGV for polyprotein translation. Because a putative signal sequence of E1 for entry into endoplasmic reticulum starts from the N-terminus of the polyprotein, and capsid-like peptides composed of basic amino acids could not be detected from the upstream region of E1, the core protein of HGV is absent, or at least not present, at the region next to 5'-UTR. Therefore, HGV could be clearly distinguished from other genera of Flaviviridae.

Amino Acid Sequence↗

PubMed1998

Prolonged systemic delivery of streptokinase using liposome.

To prolong the biological half-life of streptokinase, a thrombolytic agent, streptokinase-bearing liposome with and distearolyphosphatidyl ethanolamine-N-poly (ethylene glycol) 2000 (DSPE-PEG 2000) was prepared and evaluated. Streptokinase-bearing liposomes composed of distearolyphosphatidylcholine (DSPC), cholesterol and cholesterol-3-sulfate with DSPE-PEG 2000 was prepared by the freeze-thawing method and administered via femoral vein to rats (15,000 IU/kg). The activity of streptokinase in plasma was determined by the method based on the amidolytic activity of streptokinase-plasminogen complex. Pharmacokinetic parameters of streptokinase incorporated in liposomes were compared with those of streptokinase alone. The T1/2 and AUCinfinity of streptokinase incorporated in DSPC-PEG liposome increased 16.3- and 6.1-fold, respectively, compared with those of streptokinase alone. Streptokinase-bearing long-circulating liposome could increase the circulation time of streptokinase in blood and expect longer thrombolytic activity compared with streptokinase alone.

Animals↗

PubMed1998

Biphasic release characteristics of dual drug-loaded alginate beads.

The dual drug-loaded alginate beads simultaneously containing drug in inner and outer layers were prepared by dropping plain (single-layered) alginate beads into CaCl2 solution. The release characteristics were evaluated in simulated gastric fluid for 2 h followed by intestinal fluids thereafter for 12 h. The surface morphology and cross section of dual drug-loaded alginate beads was also investigated using scanning electron microscope (SEM). The poorly water-soluble ibuprofen was chosen as a model drug. The surface of single-layered and dual drug-loaded alginate beads showed very crude and roughness, showing aggregated particles, surface cracks and rough crystals. The thickness of dual drug-loaded alginate beads surrounded by outer layer was ranged from about 57 to 329 microns. The distinct chasm between inner and outer layers was also observed. In case of single-layered alginate beads, the drug was not released in gastric fluid but was largely released in intestinal fluid. However, the release rate decreased as the reinforcing Eudragit polymer contents increased. When the plasticizers were added into polymer, the release rate largely decreased. The release rate of dual drug-loaded alginate beads was stable in gastric fluid for 2 h but largely increased when switched in intestinal fluid. The drug linearly released for 4 h followed by another linear release thereafter, showing a distinct biphasic release characteristics. There was a difference in the release profiles between single-layered and dual drug-loaded alginate beads due to their structural shape. However, this biphasic release profiles were modified by varying formulation compositions of inner and outer layer of alginate beads. The release rate of dual drug-loaded alginate beads slightly decreased when the outer layer was reinforced with Eudragit RS100 polymers. In case of dual drug-loaded alginate beads with polymer-reinforced outer layer only, the initial amount of drug released was low but the initial release rate (slope) was higher due to more swellable inner cores when compared to polymer-reinforced inner cores. The current dual drug-loaded alginate beads may be used to deliver the drugs in a time dependent manner.

Alginates↗

PubMed1998

A familial predisposition in bronchial hyperresponsiveness among patients with allergic rhinitis.

BACKGROUND: Nonasthmatic subjects with allergic rhinitis often have bronchial hyperresponsiveness (BHR). The mechanisms responsible for BHR in asthma include genetic predisposition and airway inflammation, but the causes of BHR in allergic rhinitis are poorly understood. OBJECTIVE: The aim of this study was to investigate whether there is a familial predisposition in allergic rhinitis-associated BHR. METHODS: One hundred fifteen children with allergic rhinitis (probands) and their family members underwent methacholine bronchial challenge and skin prick tests with airborne allergens. The probands were divided into 2 groups: BHR(+) (methacholine PC20 <18 mg/mL determined by the dosimeter method; n = 42) and BHR(-) (n = 73). RESULTS: The overall prevalence of BHR was higher in family members of BHR(+) probands than in those of BHR(-) probands (23.3% [27 of 116] vs 10.5% [21 of 200], P <.01). In mothers, this difference was marked (21.4% vs 8.2%, P <.05); a similar trend was observed in fathers (16.7% vs 6.8%) and siblings (34.4% vs 18.5%), although the differences did not reach significance (.05 < P <.1). The bronchial responsiveness index (BR index), a continuous variable derived from the results of methacholine challenge, was significantly higher among family members of the BHR(+) group than those of the BHR(-) group. Furthermore, even when only family members without BHR were considered, the BR index was significantly higher among those (n = 89) of the BHR(+) group than those (n = 179) of the BHR(-) group. There was no difference in atopic status as assessed by the prevalence of atopy (or atopy index) between family members of the BHR(+) group and the BHR(-) group. CONCLUSION: Our results indicated that there is a significant familial predisposition for BHR among patients with allergic rhinitis. Further studies are needed to elucidate whether genetic factors play a role in allergic rhinitis-associated BHR.

Administration, Inhalation↗

PubMed1998

The occurrence of late asthmatic response to exercise after allergen challenge.

BACKGROUND: The determinants of late asthmatic responses to exercise remain unknown. It has been reported that they may develop in some adult subjects with asthma following a late asthmatic response to allergen. OBJECTIVE: We intended to corroborate this finding in children with asthma and to investigate which aspect of airway responses to allergen is associated with late asthmatic responses to exercise. METHODS: We studied 17 children with allergic asthma, who showed late asthmatic responses to inhaled allergen (Dermatophagoides pteronyssinus). Each underwent an exercise challenge test two days before (pre-allergen) and two days after (postallergen) an allergen inhalation challenge. FEV1 was measured at regular intervals up to ten hours after each challenge. Methacholine PC20 was measured before the allergen challenge and before the postallergen exercise challenge. RESULTS: After the pre-allergen exercise test, all the subjects showed isolated early asthmatic responses. After the postallergen exercise test, seven showed dual responses (early and late asthmatic responses) (group I) and the remaining ten showed isolated early asthmatic responses (group II). Bronchial responses to pre-allergen exercise or inhaled allergen and the severity of early asthmatic responses to postallergen exercise were similar in groups I and II. Neither before allergen inhalation nor before the postallergen exercise was methacholine PC20 different between the two groups. Methacholine dose shift caused by allergen challenge, however, was significantly greater in group I than in group II (-2.00+/-0.39 versus -1.36+/-0.53 doubling doses; P < .05). There was significant correlation between the dose shift and the magnitude of late response to the postallergen exercise in the whole group (r = 0.51, P < .05). CONCLUSION: Late asthmatic responses to exercise may develop in some children with asthma following a late asthmatic response to allergen. This phenomenon was related neither to the baseline nor to postallergen methacholine PC20 but to the extent of increased sensitivity to methacholine caused by allergen challenge.

Adolescent↗

PubMed1998

Alveolar bone formation at dental implant dehiscence defects following guided bone regeneration and xenogeneic freeze-dried demineralized bone matrix.

The present study evaluated rate and extent of alveolar bone formation in dental implant dehiscence defects following guided bone regeneration (GBR) and implantation of xenogeneic freeze-dried demineralized bone matrix (xDBM). A total of 16 titanium plasma-sprayed (TPS) and 16 hydroxyapatite-coated (HA) titanium cylinder implants were inserted in 4 mongrel dogs following extraction of the mandibular premolar teeth. Four implant sites per jaw quadrant (2 TPS and 2 HA implant sites) were prepared into extraction sockets in each dog. Buccal alveolar bone was removed to create 3 x 5 mm dehiscence defects. Two jaw quadrants in separate animals received GBR, GBR + xDBM, xDBM (control), or gingival flap surgery alone (GFS; control). Thus, four conditions were available for each implant type (TPS or HA): GBR, GBR + xDBM; xDBM and GFS. The animals received fluorescent bone labels to allow observations of rate and extent of bone formation. Animals were sacrificed at 12 weeks postsurgery and block sections were harvested for histologic analysis. There were no apparent histologic differences between TPS and HA implant defects. GBR and GBR + xDBM resulted in almost complete bone closure of the dental implant dehiscence defect. Rate of bone formation appeared higher following GBR alone. Extent of bone formation appeared somewhat greater following GBR + xDBM; however, delayed. xDBM alone did not adequately resolve the bony defect. In conclusion, GBR results in rapid, clinically relevant bone closure of dental implant dehiscence defects. Adjunctive implantation of xDBM does not appear to significantly improve the healing response in the model used.

Alveolar Process↗

PubMed1998

Influence of carbon monoxide, and its interaction with nitric oxide, on the adrenocorticotropin hormone response of the normal rat to a physico-emotional stress.

We determined whether the gas carbon monoxide (CO) altered the adrenocorticotropin hormone (ACTH) response to mild inescapable electrofootshocks, and whether it interacted with nitric oxide (NO). Peripheral injection of the NO synthase (NOS) inhibitor Nwnitro-L-arginine-methylester (L-NAME), a compound which readily crosses the blood-brain barrier, produced the expected blunting of the ACTH response to the shocks. This effect was mimicked by other arginine analogues such as L-nitroarginine (L-NNA) and NG-methyl-L-arginine (NMMA). The subcutaneous (s.c.) administration of the heme oxygenase (HO) blockers tin mesoporphyrin (SnMP) or tin protoporphyrin (SnPP) significantly decreased brain HO levels, indicating that both compounds had penetrated the brain. Blood pressure showed a modest increase in response to SnMP, and no change after SnPP. SnMP and SnPP both decreased shock-induced ACTH release, though the magnitude of this effect was slightly less than that of L-NAME. The influence of SnPP was further augmented in rats with concomitant blockade of NO formation, which suggests that both NO and CO are necessary for the full response of this axis to electrofootshocks. Finally, the ability of SnPP to significantly blunt the expression of the mRNA for the immediate early gene NGFI-B in the paraventricular nucleus (PVN) of rats exposed to shocks, indicates that the influence of CO was exerted on hypothalamic neuronal activity. Collectively, our results show that NO and CO exert a stimulatory effect on the HPA axis response to mild electrofootshocks, and that at least part of this influence takes place on hypothalamic neurons and/or their afferents.

Adrenocorticotropic Hormone↗

PubMed1998

Normal human corneal cell populations evaluated by in vivo scanning slit confocal microscopy.

PURPOSE: To analyze cellular populations in healthy human corneas. METHODS: The study group consisted of 58 eyes of 45 patients with normal corneas. The age distribution was 45 +/- 17 years (mean +/- SD; range, 20-84). Scanning slit confocal microscopy of the central corneas was performed. The images were analyzed visually for cell morphology, and the densities and areas of cells were measured. RESULTS: No statistically significant differences were measured in cell densities or cell areas of any corneal layer between female and male patients (p = 0.22-0.50) nor between right and left eyes (p = 0.16-0.45). The area of superficial epithelial cells was 913 +/- 326 microm2 (mean +/- SD; range, 518-2,112), and the superficial epithelial cell density was 1,213 +/- 370 cells/mm2 (mean +/- SD; range, 473-1,929). The area of basal epithelial cells was 177 +/- 19 microm2 (mean +/- SD; range, 138-242), and the basal epithelial cell density was 5,699 +/- 604 cells/mm2 (mean +/- SD; range, 4,135-7,267). The average apparent keratocyte density was 1,058 +/- 217 cells/mm2 (mean +/- SD; range, 604-1,599) in the anterior stroma, and 771 +/- 135 cells/mm2 (mean +/- SD; range, 493-1,145) in the posterior stroma. The difference in apparent keratocyte densities between the anterior and posterior stroma was statistically significant (p < 0.001). The average endothelial cell area was 334 +/- 51 microm2 (range, 273-553), and the cell density was 3,055 +/- 386 cells/mm2 (mean +/- SD; range, 1,809-3,668). The endothelial cell density had a negative, statistically significant correlation with age (r = -0.68, p < 0.001). The densities of the other corneal cell layers did not have a statistically significant correlation with age. CONCLUSION: In vivo scanning slit confocal microscopy is a useful tool for studying corneal cell populations. Central corneal cell densities were found to decrease significantly with age only in the endothelium. For the first time in human corneas using in vivo confocal microscopy, this study statistically confirms a higher apparent number of keratocytes in the anterior stroma than in the posterior stroma.

Adult↗

PubMed1998

In vivo confocal microscopy of Fuchs' endothelial dystrophy.

PURPOSE: The purpose of this study is to analyze in vivo confocal microscopic findings of corneas with Fuchs' endothelial dystrophy. METHODS: Central corneas of 17 eyes of 11 patients aged 41-86 years were examined using in vivo scanning slit confocal microscopy after being diagnosed with Fuchs' endothelial dystrophy. The cellular structure of the corneas was analyzed morphologically and quantitatively and compared to control results from 22 healthy corneas. RESULTS: Bullae were detected in the basal epithelial layer of one eye. Eight of 17 eyes (47%) exhibited an abnormal Bowman's layer: diffuse bright reflection and absence of nerves. Eleven eyes (65%) exhibited abnormal anterior stroma: lacunae and diffuse increased light reflection due to edema. In 12 eyes (71%), lacunae or dark bands 5-20 microm wide against increased background reflection were noted in the posterior stroma. Descemet's membrane was thickened in all eyes. Dark bands were detected in six eyes (35%). Guttae (137-1,231/mm2) 20-40 microm in diameter were found in every endothelial cell layer. The mean endothelial cell count was 1,202 +/- 850 (cells/mm2 +/- SD; range, 0-2,735). There was a positive correlation between endothelial cell counts obtained by specular microscopy and those obtained by confocal microscopy (r = 0.95). CONCLUSION: In vivo confocal microscopic findings of Fuchs' endothelial dystrophy are described for the first time in a series of cases. Pathological changes in Fuchs' dystrophy were detected in all corneal layers, more frequently in the posterior layers. Endothelial cell counts obtained with confocal microscopy were statistically similar to those obtained with standard specular microscopy.

Adult↗