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Biomedical subjects

R J Yu

Publications and source records attributed to R J Yu.

At least 19 recordsLinked to original sources
PubMed1997

Citric acid increases viable epidermal thickness and glycosaminoglycan content of sun-damaged skin.

BACKGROUND: Recently, there has been an exponential increase in the use of alpha-hydroxy acids in dermatologic practice. Their inclusion in a myriad of cosmetic preparations underscores their popularity. Among the clinical effects of alpha-hydroxy acids are their ability to prevent the atropy resulting from potent topical corticosteroids, improve the appearance of photoaged skin, and correct disorders of keratinization. Despite this range of desirable effects, very little is known about the specific changes produced by various alpha-hydroxy acid preparations in the epidermis and dermal extracellular matrix. Previous work by others has demonstrated the ability of another alpha-hydroxy acid to increase viable epidermal thickness, and dermal glycosaminoglycans. OBJECTIVE: In this study, we examined the effect of 20% citric acid lotion, as compared with vehicle alone, on skin thickness, viable epidermal thickness, and dermal glycosaminoglycan content. Biopsy samples were harvested after 3 months of treatment. RESULTS: Image analysis of biopsy sections revealed increases in viable epidermal thickness and dermal glycosaminoglycans in treated skin. CONCLUSIONS: Topical citric acid produces changes similar to those observed in response to glycolic acid, ammonium lactate, and retinoic acid including increases in epidermal and dermal glycosaminoglycans and viable epidermal thickness. Further studies of citric acid and other alpha-hydroxy acids are warranted to clarify their clinical effects and mechanisms of action.

Administration, Cutaneous↗
PubMed1996

Effects of alpha-hydroxy acids on photoaged skin: a pilot clinical, histologic, and ultrastructural study.

BACKGROUND: alpha-Hydroxy acids (AHAs) have been reported to improve aging skin. The mechanisms of action of AHAs on epidermal and dermal compartments need clarification. OBJECTIVE: Our purpose was to determine the effects of AHAs on photoaged human skin by clinical and microanalytic means. METHODS: Patients applied a lotion containing 25% glycolic, lactic, or citric acid to one forearm and a placebo lotion to the opposite forearm for an average of 6 months. Thickness of forearm skin was measured throughout the study. Biopsy specimens from both forearms were processed for analysis at the end of the study. RESULTS: Treatment with AHAs caused an approximate 25% increase in skin thickness. The epidermis was thicker and papillary dermal changes included increased thickness, increased acid mucopolysaccharides, improved quality of elastic fibers, and increased density of collagen. No inflammation was evident. CONCLUSION: Treatment with AHAs produced significant reversal of epidermal and dermal markers of photoaging.

Aged↗
PubMed1996

Increased factor XIIIa transglutaminase expression in dermal dendrocytes after treatment with alpha-hydroxy acids: potential physiologic significance.

BACKGROUND: Topical alpha-hydroxy acids (AHAs) have been shown to improve photoaging in human skin. OBJECTIVE: We studied factor XIIIa transglutaminase expression in dermal dendrocytes (DDs) and mast cell degranulation after treatment of the skin with AHAs. METHODS: Skin biopsy specimens obtained from patients after 4 to 8 months of treatment with lotions containing 25% AHAs were evaluated for factor XIIIa transglutaminase expression with immunoperoxidase and electron microscopy. Immunoperoxidase-stained sections were studied by means of semiquantitative methods and image analysis. Mast cell degranulation was studied by image analysis. RESULTS: Increased factor XIIIa transglutaminase expression was seen after treatment with AHAs. All treated sites had increased scores compared with control sites by semiquantitative methods. Seventy-five percent of treated sites showed an increased mean area over control sites of factor XIIIa transglutaminase positivity with image analysis. These results correlated with an increased level of mast cell degranulation in treated sites and with activation of DDs as seen by electron microscopy. CONCLUSION: Treatment of the skin with AHAs leads to mast cell degranulation and increased expression of factor XIIIa transglutaminase by activated DDs. Mast cell degranulation may lead to activation of DDs and increased factor XIIIa transglutaminase expression, via the action of tumor necrosis factor-alpha. We speculate that clinical and histologic improvement in photoaged skin after treatment with AHAs may be somehow related to this process.

Administration, Cutaneous↗
PubMed1993

[A comparative trial of hemodynamics and pulmonary function in patients with chronic lung disease complicated with or without pulmonary hypertension during exercise].

In order to determine the hemodynamics and pulmonary function during exercise, 20 patients with chronic lung disease complicated with (group A) or without (group B) pulmonary hypertension were studied. FEV1% in group A was lower than that in group B at rest, the increase in VE, VO2, O2-pulse in patients with pulmonary hypertension were lower than in patients without it during exercise. We speculated that exercise ability in patients with chronic lung disease may be effected by not only ventilation but also increased pulmonary arterial pressure.

Aged↗
PubMed1993

20-item neonatal behavioral neurological assessment used in predicting prognosis of asphyxiated newborn.

From January 1989 to June 1990, 13 institutions in our country studied jointly the application of a 20-item neonatal behavioral neurological assessment (NBNA) in asphyxiated babies. Of 145 cases, 125 were followed up to 1-2 years of age. The results showed that in predicting prognosis, the sensitivity and specificity of NBNA score at 7 days after birth were 88.9% and 82.6% and 12-14 days, 84.6% and 97.4% respectively. Its value in predicting prognosis is superior to Sarnat degree, cranial CT and B ultrasound. This method is practical, economical and reliable. It is worth popularizing.

Apgar Score↗
PubMed1993

[CT in hypoxia brain damage in asphyxia-prognostic estimation].

60 newborns with severe asphyxia 3-12 days after delivery were examined by CT. Low density in brain was found in 55 newborns (91.7%), and cerebral hemorrhage in 34 (56.7%). To detect MDI CDCC measurement by Balay's modification was done in 54 babies of whom 44 cases were within normal limits (MDI > 70). Low intelligence was found in 10 babies (16.7%), and 6 (14%) died. No cerebralplagia was found. No intelligence change was found in normal or mild CT changes. In 50 babies with severe or moderate change in CT scan, 16 (32%) showed poor prognosis (P < 0.05). Sensitivity and specificity for CT were 100% and 22.8% respectively, but the value of neonatal behavioral neurological assessment (NBNA) was 83.3% and 93.2%. We conclude that the mortality rate and poor prognosis are related to the degree of involvement of brainwhite matter or hemorrhage, and that CT examination is valuable in estimating the prognosis especially in combination of NBNA.

Asphyxia Neonatorum↗
PubMed1993

[The comparison of left and right heart function with lung function in patients with rheumatic valvar heart disease].

According to the characteristics of changes of heart and lung function at different stages 25 patients with rheumatic valvar heart disease could be classified into three stages: 1. The stage of normal lung ventilation and volumes; 2. Stage of obstructive ventilatory function; 3. The stage of mixed ventilatory defects associated with right heart failure. As pulmonary artery pressure increased right ventricle work became elevated and left ventricle work decreased. There was an inverse correlation of vital capacity with per minute work of right ventricle.

Adult↗
PubMed1991

[Effects of nifedipine on pulmonary hypertension in patients with chronic obstructive pulmonary diseases--a comparison with oxygen administration].

We evaluated the effects of the calcium channel blocker nifedipine (Nf) as a vasodilator compared with oxygen administration on pulmonary hypertension and right ventricular performance in 15 patients with COPD. 1. Compared with baseline, sublingual administration of Nf (average dose 39.3mg) decreased mean pulmonary artery pressure (mPAP) and total pulmonary vascular resistance (TPVR) significantly. Cardiac index (CI) and oxygen transport were increased. PaO2 were unchanged and PvO2 were slightly increased after administration of Nf. 2. Compared with oxygen administration, Nf caused significant fall of TPVR. CI and oxygen transport increased. 3. In eleven of 15 patients, continued hourly Nf doses (from 20 to 60mg) produced a significant reduction in mPAP and TPVR. All patients but one did not produce symptomatic systemic hypotension. We considered that higher dose (30mg) of Nf was required to produce marked hemodynamic response in patients with COPD without any side effect.

Administration, Sublingual↗
PubMed1991

Twenty-item behavioral neurological assessment for normal newborns in 12 cities of China.

Based on the method of Brazelton and Amiel-Tison for behavioral neurological measurement in the newborn and our own experience, we formulated a 20-item neonatal behavioral neurological assessment (NBNA). For setting up a practical method and a normal range of its scores in China, we examined 714 normal newborns (male 369, female 345), with NBNA at the age of 2-3, 12-14, 26-28 days for a total of 2,142 times, in 12 provinces of China from May to October 1988. NBNA contains 5 clusters: behavior (6 items); passive tone (4 items); active tone (4 items); primary reflexes (3 items); and general assessment (3 items). Each item has 3 scales (0,1,2). Twenty items have a maximum of 40 scores. Among the 2,142 times examined, 90.4% of the 714 newborns had 39-40 scores, 97% greater than 37 and none below 35. Measurements of the first, second and third time revealed that the total scores increased with age. The difference was statistically significant. The abilities of auditory and visual orientations and active neck tone improved obviously with age. NBNA shows distinct stability and reliability. The score is not influenced by geographic location; the scoring system is simple and the manipulation takes only ten minutes.

Birth Injuries↗
PubMed1989

Alpha hydroxy acids: procedures for use in clinical practice.

Alpha hydroxy acids and alpha keto acids applied topically in lower concentrations reduce the thickness of hyperkeratotic stratum corneum by reducing corneocyte cohesion at lower levels of the stratum corneum. This property permits efficient clinical control of dry skin, ichthyosis, follicular hyperkeratosis, and other conditions characterized by retention of stratum corneum. Applied topically in higher concentrations, these acids cause epidermolysis. This property provides a new alternative for treating seborrheic keratoses, keratoses commonly known as "age spots," actinic keratoses, and verrucae vulgares; all of which lesions involve distinct epidermal hyperplasia as well as retention of stratum corneum. Facial wrinkles can be modified with topical alpha hydroxy acids, applied in higher concentrations as office procedures, and concomitant daily home application of lower concentrations.

Acne Vulgaris↗
PubMed1988

[Experimental chemotherapy of human gastric cancer cell lines in vitro and in nude mice].

Cytotoxic effects of allyl trisulfide (Alt, a synthetic chemical identical with one of the main active principles of garlic), 5 FU, MMC and DDP on SGC 7901 ( a moderately differentiated human gastric adenocarcinoma cell line) and MGC 803 (a poorly differentiated human gastric mucoadenocarcinoma cell line) had been reported before. In this paper, effects of repeated two doses of each drug and the combination of two drugs on these two cell lines were studied using relative clone-survival test. The inhibitory effects of Alt, MMC alone or combined on MGC tumor in nude mice were observed. No drug resistance was found when any one of the four agents at the same concentration were repeated twice separately at 60 hour interval in vitro. The cytotoxic effect of the repeated two doses was approximately equal to that of the single dose at double concentration. The in vitro test of combinations of two drugs showed that Alt plus MMC or 5 FU plus DDP had markedly synergistic effect on MGC cells; 5 FU plus DDP had markedly synergistic effect on SGC cells. The inhibition test on the growth of MGC tumor in nude mice indicated that the inhibition rates of Alt, MMC alone or combined were 58.3%, 86.3% and 84.3%. The systemic toxic effect of MMC alone was severe, whereas Alt alone or MMC plus Alt showed mild toxicity. For this reason, Alt plus MMC is recommended for clinical trials on poorly differentiated gastric cancer. In addition, for the comparison of in vitro test dose and clinical dose of each drug, the principle of clinical adult dose range (CADR) is proposed.

Adenocarcinoma↗
PubMed1984

Hyperkeratinization, corneocyte cohesion, and alpha hydroxy acids.

Hyperkeratinization is a primary or fundamental event in a majority of today's skin disorders. Hyperkeratinization is usually the result of decreased desquamation due to increased corneocyte cohesion. Strength of corneocyte cohesion is determined by strength of intercellular bonding. Intercellular bonding is weakened by water and diminished by retinoids and alpha hydroxy acids (AHAs). Conversely, bonding is strengthened or enhanced by dehydration, vitamin A deficiency, and some alpha acetoxy acids (AAAs). Agents that control or modify keratinization can be useful in treatment of many skin disorders.

Animals↗