Biomedical subjects

C Hong

Publications and source records attributed to C Hong.

At least 109 records · Page 6Linked to original sources

PubMed1991

Heterotopic cardiac transplantation decreases the capacity for rat myocardial protein synthesis.

Heterotopic cardiac isografts are vascularly perfused hearts that maintain structural and functional integrity for prolonged periods of time. When placed in an infrarenal location, the heart is hemodynamically unloaded and undergoes negative growth, leading to cardiac atrophy. At 7 and 14 days after transplantation, the transplanted heart was decreased in size compared with the in situ heart (p less than 0.001). To assess the possible mechanism(s) to account for this reduction in size we studied in vivo rates of total left ventricular (LV) protein synthesis, total LV RNA content, and 18S ribosomal RNA content by nucleic acid hybridization. The LV protein synthetic rate was 4.7 and 5.3 mg/day in the in situ heart and was significantly decreased to 2.9 and 2.7 mg/day in the transplanted hearts at 7 and 14 days, respectively. LV RNA content of the transplant declined to 53% and 48% of the in situ value at 7 and 14 days, respectively. Hybridization studies revealed that LV 18S ribosomal subunit content was reduced proportionately to total RNA in the heterotopic hearts. As a result of these changes, there was no significant difference in the efficiency of total LV protein synthesis between the in situ and transplanted hearts. The present studies demonstrate that the hemodynamic unloading and cardiac atrophy that is characteristic of heterotopic cardiac transplantation is accompanied by a decrease in LV total RNA content and 18S RNA, resulting in a decreased capacity for myocardial protein synthesis.

Animals↗

PubMed1991

Isovolumic loading prevents atrophy of the heterotopically transplanted rat heart.

Heterotopically (infrarenal) transplanted cardiac isografts are histologically normal, spontaneously beating, hemodynamically unloaded hearts that undergo rapid and predictable atrophy. To study the factors that regulate cardiac growth we examined the effect of left ventricular (LV) isovolumic balloon placement on the weight, in vitro protein synthesis rate, and LV RNA content of the transplanted heart. At day 0 the donor LV weight was 367 +/- 8 mg, which decreased to 226 +/- 14 mg (p less than 0.001) after transplantation. Isovolumic loading with a latex balloon (volume, 111 +/- 10 microliters) significantly increased the LV weight of the transplanted heart to 397 +/- 13 mg when compared with that of the unloaded heart 14 days after surgery and prevented the atrophy when compared with the LV weight at day 0. Sham-loaded transplants had LV weights of 256 +/- 17 mg, which did not differ from the LV weight of unloaded transplanted hearts. Protein synthesis rates (nmol lysine/LV/hr) and total LV RNA and LV 18S RNA content were significantly greater in the balloon-loaded hearts when compared with the unloaded isografts and returned to levels similar to those measured in the in situ hearts. The ability of isovolumic loading of the LV to prevent atrophy via increased protein synthesis and the maintenance of LV RNA in the heterotopically transplanted heart further supports the important role of cardiac work in the regulation of cardiac growth.

Animals↗

PubMed1991

Effect of apraclonidine hydrochloride on acute introacular pressure rise after argon laser iridotomy.

To determine the effect of apraclonidine hydrochloride on the acute intraocular pressure (IOP) rise after argon laser iridotomy (ALI), a double-masked comparative study was carried out. Twenty-nine eyes (20 patients) with angle-closure glaucoma underwent ALI. Eighteen eyes were treated with apraclonidine, and the remainder received a placebo 1 hour before and immediately after ALI. The mean IOP increase in the apraclonidine group was lower than that in the placebo group at each postlaser interval (p less than 0.01). Although the average value of the maximal increases of IOP after ALI in the apraclonidine group was 4 mmHg, that in the placebo group was 16 mmHg. In the placebo group, 27.3% (3 out of 11 eyes) experienced an IOP rise greater than or equal to 10 mmHg. However, that kind of IOP rise was not found in the apraclonidine group (0 out of 18 eyes) (p less than 0.01). Ocular or systemic side effects were not found in a series of examinations in both groups. Therefore, apraclonidine proved to be effective in lowering the IOP rise after ALI.

Acute Disease↗

PubMed1990

Newly established human retinoblastoma cell lines exhibit an "immortalized" but not an invasive phenotype in vitro.

Retinoblastoma (RB), an intraocular childhood tumor occurring in a hereditary (mostly bilateral) or non-hereditary (unilateral) form, is associated with the inactivation of both alleles of a putative tumor suppressor gene (RB-I) located on chromosome 13q14. Both the process of RB development and the biological characteristics of RB cells are as yet poorly understood. We have established 7 new RBL lines (RBL13, RBL14, RBL18 and RBL30, derived from unilateral RB; and RBL7, RBL15 and RBL20, derived from bilateral RB). Southern blot analyses of restriction fragment length polymorphisms in DNA samples from 6 cell lines revealed loss of constitutional heterozygosity at one or several polymorphic loci on chromosome 13 in 4 cases. Gross deletions involving the RB-I locus and amplification of the N-myc gene were not detected in any of the RBL lines. The phenotypic properties of the RBL lines were analyzed in comparison with cells from the original RB tumors, with 4 RB lines established by others (RB383, RB355, RB247C3 and Y79) and with the adenovirus-EIA-transformed human retinoblast line HER-Xhol-CC2. It was found that RB tumors consist of phenotypically heterogeneous cell subpopulations with varying nutrient requirements and differentiation potential in vitro. All cell lines showed the typical characteristics of established ("immortalized") cells. In some cases, cells from original RB tumors or cell lines were able to form colonies when cell aggregates of 2-10 cells were suspended in semi-solid agar medium; however, anchorage-independent colonies never developed from single cells. Cell lines RBL13, RBL18, RB247C3, RB355, RB383 and Y79 were tested for invasion into embryonic chick heart fragments in vitro and found to be non-invasive. None of the RBL or RB lines were tumorigenic in nu/nu (T-) mice. Y79 cells (propagated in culture for many years) exhibited properties distinctly different from those of the other cell lines, and thus cannot be considered phenotypically representative of RB cells.

Animals↗

PubMed1990

Cardiac atrophy in the heterotopically transplanted rat heart: in vitro protein synthesis.

Heterotopic cardiac isografts are vasculary perfused organs that maintain structural and functional integrity. We have used this model to study the time course of change in total heart and left ventricular size which results from mechanical unloading of the myocardium. When compared to the in situ (working) heart there is a 19% decrease in the size of the heterotopic (non-working) heart (P less than 0.01) as early as 3 days post-transplantation. By 14 days there is 50% decrease in the size of the transplanted heart which is maintained at this atrophic size when measured after 4 weeks. Left ventricular protein synthesis was assayed by the simultaneous in vitro perfusion of the host and transplanted hearts under identical hemodynamic conditions. The hourly incorporation of 14C-lysine into total left ventricular protein was 21 nmol in the transplant compared to 50 nmol in the in situ heart (P less than 0.01). This incorporation remained significantly lower throughout the period of study. In contrast, both the total (mumol lysine/g protein nitrogen/h) and fractional rates of protein synthesis which were lower in the transplanted left ventricle at days 3 and 7 returned to control values by day 28. The present studies demonstrate that heterotropic cardiac transplantation leads to a prompt and reproducible decline in cardiac mass and in total protein synthesis. These studies further support the role of cardiac work as an important determinant in the regulation of cardiac protein synthesis.

Animals↗

PubMed1990

The identification of females within the subfamily Ostertagiinae Lopez-Neyra 1947.

As a result of the examination of many thousands of female nematodes classified as belonging to the sub-family Ostertagiinae Lopez-Neyra 1947, it became possible to compile descriptions of different female types, each of which corresponds to a polymorphic species as determined by male morphology. The female types have been designated as follows: Ostertagia ostertagi (males O. ostertagi and O. lyrata), Ostertagia circumcincta (males O. circumcincta, O. trifurcata and Teladorsagia davtiani), Ostertagia leptospicularis (males O. leptospicularis and O. kolchida) and Spiculopteragia asymmetrica (males S. asymmetrica and Apteragia quadrispiculata).

Animals↗

PubMed1990

Detection of early visual field change in ocular hypertension using STATPAC.

Perimetric tests were performed on 32 ocular hypertensive eyes (17 patients) with the C-30-2 threshold program of the Humphrey Visual Field Analyzer. The global indices of 32 ocular hypertensive eyes were compared with those of 34 normal eyes (17 controls). None of the 34 normal eyes had visual field sensitivity loss. However, three out of 32 ocular hypertensive eyes, which is 0.4%, had visual field sensitivity loss. Of these three eyes, two eyes showed generalized depression (MD, P less than 5%) and one eye showed paracentral scotoma.

Adolescent↗

PubMed1990

Detection of glaucomatous visual field defect using a screening program of Humphrey Field Analyzer.

To evaluate its clinical efficacy, we report the results of Armaly central field screening test in comparison with those of central 30-2 threshold test of Humphrey Field Analyzer. In 83 cases of normotensives, ocular hypertensives, and glaucoma patients with open-angle or narrow-angle enrolled in this study, a total of 143 eyes were examined. Fifty-four out of 61 patients (88.5%) and 73 out of 81 eyes (90.1%) with visual field defects were detected by the Humphrey Field Analyzer screening test. Eight eyes out of 81(9.9%) with visual field defects detected by the screening test were confirmed as false positive. All points of false positive were solitary, which tended to occur more frequently on superior visual field. A false negative of eight eyes out of 62 (12.9%) detected by the screening test was confirmed by the threshold test, which was more frequent on superior field and shown to be located more peripherally from the fixation point. There was no significant difference in either central sensitivity or age of the false positive and negative.

Adult↗

PubMed1990

Trauma outcome analysis of two Canadian centres using the TRISS method.

In this retrospective study, the TRISS method of trauma care analysis is used to compare trauma care at the Hamilton General Hospital (HGH) and the Ottawa Civic Hospital (OCH) with the standards reported in the Major Trauma Outcome Study (MTOS). A total of 274 adult patients with multiple-system injuries were studied; their demographic data, Trauma Scores (TS) on arrival to the Emergency Room, and Injury Severity Scores (ISS) were reviewed. The TRISS scores and Z and M statistics were then calculated. In the Hamilton group, 106 consecutive patients from April through July 1987 were studied. The majority of patients (72%) were male, and the median age was 26 years. The majority of patients (96.2%) sustained blunt trauma, with motor vehicle accidents (MVA) being the most common (76.4%) mechanisms of injury. Fifty-four (51%) of the patients were transferred from outlying hospitals. The Z and M statistics were -0.05 and 0.92, respectively. In the Ottawa group, 168 consecutive patients from April 1987 through October 1988 were studied. The majority of patients (73%) were male, and the median age was 39 years. Blunt trauma accounted for the majority (91.7%) of injuries, with MVAs being responsible for 58% of injuries. Most patients (63.5%) were transferred from regional hospitals. The Z and M statistics were 1.20 and 0.56, respectively. We conclude that the survival statistics of trauma patients treated at both centres are comparable to those of trauma patients in the MTOS.

Adult↗

PubMed1989

Interpretation of abomasal worm burdens in cattle.

The significance of the worm burden in the diagnosis of parasitic gastroenteritis is examined. It is emphasised that the worm population is in a dynamic state with the calf constantly losing part of its worm burden while picking up new infective larvae. The numbers and proportion of late fourth stage Ostertagia ostertagi larvae gives an indication of the success of the animal in controlling its worm burden. During an examination of the worm population it is also necessary to look at the condition and degree of development of adult female worms to assess the efficiency of the calf's acquired resistance to infection.

Abomasum↗

PubMed1989

Development of protection and of self-cure in lambs infected daily with Ostertagia circumcincta.

Lambs were infected daily with 1000 Ostertagia circumcincta larvae. At intervals of 4 weeks groups of lambs were each challenged with a dose of 28,000 larvae, and their worm burdens compared with those of unchallenged controls. The measure of their ability to resist a challenge infection, which would have determined their degree of "protection", was obscured by the separate phenomenon of self-cure. Evidence suggested that the different manifestations of self-cure were determined by the state of resistance of the host and followed a set chronological sequence.

Animals↗

PubMed1989

The influence of tissue expanders on grafted vessels.

Interpositionally grafted arteries and veins were expanded with a 20cc tissue expanders in 50 Sprague-Dawley rats. The grafts were done on both hind legs, one side was expanded and the remaining side was used as control. The average gain in length of expanded grafted arteries and veins was over 4 and 6 times that of the controls respectively. The differences in the patency rates between expanded and control grafts were not statistically significant. Histologic examination revealed that there were no changes in the areas of the media and lengths of the inner elastic laminae of the expanded arterial grafts. In both expanded and control vein grafts, marked intimal thickening was noticed, although these changes were not statistically significant. Expansion of grafted vessels can be safely carried out without loss of vessel patency.

Animals↗

PubMed1988