Biomedical subjects
V Chen
Publications and source records attributed to V Chen.
Limited application of mometasone furoate on the face and intertriginous areas: analysis of safety and efficacy.
Explore the source record for details and available documents.
Descriptive analysis of breast cancer in African-American women at Howard University Hospital, 1960-1987.
This article describes breast cancer cases seen at the Howard University Hospital from 1960 through 1987 using information from the database of the Tumor Registry, established in 1960. Clinical information at presentation is presented as well as a description of reproductive and demographic characteristics. Pre- and postmenopausal women are compared, revealing differences in reproductive experience. This may contribute to the increasing incidence of breast cancer seen among younger women in recent years. This is of particular interest because the classic excess of nulliparous women among breast cancer cases is not seen among the population described here.
Keratoplasty in the presence of anterior chamber drainage tube.
Explore the source record for details and available documents.
Effects of catecholamine stimulation on myocardial hibernation.
We have recently shown that low-flow (10%) ischemia in the isolated piglet heart causes an abrupt fall in mechanical function and metabolic activity (acute hibernation), with nearly complete preservation of high-energy phosphates and glycogen after 2 hours of ischemia. We attempted to determine if norepinephrine, as occurs in vivo, would modify the hibernation process. Piglet hearts were perfused at 37 degrees C with red blood cell-enhanced Krebs-Henseleit solution. Performance of the left ventricle was assessed isovolumetrically. With control coronary flow, norepinephrine (40 ng/ml) caused a approximately 50% increase in pressure-rate product and the rate of change of pressure. When coronary flow was reduced to 10%, these measures fell to levels identical to those of ischemic hearts not exposed to norepinephrine. Changes in myocardial O2 metabolism paralleled mechanical function. Lactate release was quantitatively similar in both groups. However, myocardial adenosine triphosphate was reduced from 29 +/- 1 to 13 +/- 2 mumol/gm and glycogen from 300 +/- 46 to 77 +/- 15 mumol/gm by the presence of norepinephrine. Left ventricular compliance was reduced to 51 +/- 5%, compared with 87 +/- 8% in the group without norepinephrine (p less than 0.001). In the norepinephrine group, correlation between left ventricular stiffness and adenosine triphosphate was poor (r = -0.32). Thus hibernating myocardium does not manifest progressive deterioration in the presence of high concentrations of norepinephrine. Diastolic function is less well preserved, however.
Oxidative metabolism and mechanical function in reperfused neonatal pig heart.
Oxidative metabolism in reperfused neonatal myocardium has not been characterized. A blood-perfused isovolumic heart preparation was used to quantify metabolic and mechanical responses of the neonatal left ventricle to global normothermic ischemia and reperfusion. Hearts from piglets aged 2-7 days were subjected to either 2 hrs of total ischemia at 37 degrees C followed by 1 hr of reperfusion or 3 hrs of perfusion alone; glucose and palmitate oxidation were measured in separate experiments by incorporation of the appropriate [14C]-labeled substrate into the perfusate. In the pre-ischemic period, glucose, palmitate, and lactate contributed 10%, 41%, and 36%, respectively, to oxidative metabolism. After 2 hrs of total normothermic ischemia, oxidation of exogenous glucose was 165% and 229% of control values at 30 and 60 minutes of reperfusion, respectively; palmitate oxidation was 110% and 143% of control values at these times. Despite increased glucose oxidation, palmitate oxidation accounted for 69% of myocardial oxygen consumption after 1 hr of reperfusion, with glucose responsible for 25%. Lactate use was minimal during reperfusion. Reperfusion was accompanied by rapid and parallel recovery of oxygen utilization, mechanical function, and high-energy phosphates. The neonatal piglet heart demonstrates significant metabolic and mechanical tolerance to prolonged ischemia. Although glucose utilization increased markedly, palmitate was the primary substrate for energy production in the post-ischemic neonatal heart.
Recombinant alpha-2 interferon gel treatment of recurrent herpes genitalis.
Topical recombinant alpha-2 interferon treatment of recurrent genital herpes was studied in a randomized, double-blind, placebo controlled clinical trial. Three hundred and eighty-seven patients were treated at eight study centers with either interferon gel or placebo four times daily for four days. Interferon therapy caused a 26% decrease in the duration of viral shedding. For male patients, there were also significant decreases in the time to crusting (17%) and duration of pain (34%) and itching (21%). For patients with recurrent genital herpes, treatment with topical interferon was found to be effective in decreasing the duration of viral shedding and, for males, pain, itching and time to crusting.
Exfoliation syndrome after cataract extraction.
The authors describe three cases in which exfoliative material was noted on the posterior surface of intraocular lenses, years after extracapsular cataract extraction and lens implantation in eyes where no exfoliative material was seen before the operation. All three cases had an open posterior capsule before the exfoliative material was first seen. This phenomenon has not been previously presented in the literature.
A morphological study of rabbit corneas after laser keratectomy.
We have examined the morphology of the collagen and proteoglycans in rabbit corneas that have undergone excimer laser photorefractive keratectomy using a clinical, 193 nm excimer laser. The photoablation was carried out to a stromal depth of 100 microns and a diameter of 6 mm. All ablated corneas developed a haze that was most intense between week 4 and week 8 and which showed no improvement after week 16. The corneas were stained with the cationic dye cuprolinic blue to visualise proteoglycans and were then processed for transmission electron microscopy. The ultrastructural location of proteoglycans (keratan sulphate and dermatan sulphate) was observed in the corneal wounds at different time intervals. Corneas that had undergone steroid treatment post-operatively were also examined. In the healing tissue proteoglycan filaments of abnormal size were observed, which became most prominent after 2 weeks. As healing progressed these abnormal filaments decreased but after 45 weeks some were still present, indicating that the proteoglycan content had not returned to normal.
Acute hibernation and reperfusion of the ischemic heart.
BACKGROUND: Recovery from prolonged low-flow ischemia was studied in isolated, isovolumically beating neonatal piglet hearts (n = 11) and compared with controls (n = 5). METHODS AND RESULTS: Hearts were perfused with red blood cell-enhanced Krebs-Henseleit buffer with physiological oxygen-carrying capacity. Left ventricular mechanical function was assessed with a fluid-filled balloon. Measurements of peak systolic pressure, pressure-rate product (PRP), and +dP/dtmax were obtained at various filling pressures. Myocardial oxygen delivery and metabolism (MVO2) and lactate uptake were measured at 30-minute intervals. Control data were obtained with coronary flow (CF) set at 2 ml.min-1.g-1. CF was then reduced to 0.2 ml.min-1.g-1 for 2 hours. Thereafter, reperfusion was instituted at control levels. Hearts not subjected to ischemia were studied at identical time intervals. In these, function remained at greater than 80% after more than 3.5 hours of study. Reduction of CF to 10% was accompanied by an abrupt diminution in function (pressure-rate product) and MVO2 to 20% of control and by lactate release. These measures remained constant for the full 2 hours of ischemia. Incremental return of CF caused a lockstep increase in mechanical function and metabolism. At 30 minutes of reperfusion, PRP was 78% of time-matched controls (p = 0.05), and dP/dtmax did not differ. Increasing calcium to 5 mmol/l returned PRP (and dP/dtmax) to preischemia levels. Myocardial ATP and creatine phosphate concentrations were identical in both groups, although glycogen was lower in the ischemic hearts. CONCLUSIONS: Acute hibernation is associated with protection of the in vitro heart from prolonged normothermic ischemia. Systolic function was only modestly lower, and velocity (dP/dtmax) did not differ from control hearts. The minimal "stunning" was fully reversible with calcium.
Oblique orientation of incisions in four-incision radial keratotomy.
Explore the source record for details and available documents.
Adoptive transfer of anti-cytomegalovirus effect of interleukin-2-activated bone marrow: potential application in transplantation.
This work is a continuation of our studies that showed that interleukin-2 (IL-2)-activated murine bone marrow (ABM) cells have potent cytotoxic potential against murine cytomegalovirus (MCMV)-infected targets in vitro, without loss of reconstitutive ability in vivo. Our data show that ABM cells lyse the MCMV-infected cells in vitro, at both acute and chronic stages of infection; this lysis is specific for the MCMV-infected cells. ABM cells supplemented with IL-2 therapy virtually eradicated the viral infection and prolonged the survival of MCMV-infected Balb/c mice, whether or not they were immunocompromised by irradiation (P less than .001 in both situations). Efficacy of ABM cells alone or IL-2 alone was less than the combination of ABM cells and IL-2. The efficacy of combination treatment with ABM cells and IL-2 in improving the survival of MCMV-infected mice was comparable, whether used in a preventive or a therapeutic setting. Therapy with ABM plus IL-2 also prevented the reactivation of chronic MCMV infection after irradiation. Preliminary findings indicate that Thy-1+ and asialo GM1+ cells limited the MCMV proliferation by approximately 30% and 80%, respectively, while BM macrophages limited the proliferation of MCMV by 100%. These results suggest that BM transplantation (BMT) with ABM cells followed by IL-2 therapy may constitute a novel strategy to improve the host resistance against cytomegalovirus infection after BMT.
Black tobacco, maté, and bladder cancer. A case-control study from Uruguay.
A case-control study of bladder cancer involving interviews with 111 incident cases and 222 controls was carried out in Montevideo, Uruguay. The analysis was conducted separately for each sex. Point estimates of relative risk associated with smoking variables, ingestion of infusions of the herb Ilex paraguariensis (maté), and selected dietary items were obtained by stratified and logistic regression analysis. Among men, smokers of black tobacco showed a relative risk (RR) 2.7 higher than blond tobacco smokers and maté exposure showed a significant dose-response, after adjustment for age, residence, social class, hospital, type of tobacco, smoking intensity, smoking duration, and vegetable consumption, with a seven-fold increase in risk for heavy consumers. Joint exposure to type of tobacco and maté consumption showed a multiplicative effect. Women showed a similar increase in risk with maté consumption. The results suggest that the high mortality rates of bladder cancer observed in Uruguay could be explained by the combined effect of black tobacco smoking and maté ingestion.
Clinical use of the 193-nm excimer laser in the treatment of corneal scars.
Phototherapeutic keratectomy using a 193-nm excimer laser was performed at four centers on 33 sighted patients with corneal opacity and/or irregular astigmatism. Pathologic conditions included anterior stromal and superficial scarring from postinfectious and posttraumatic causes, including inactive herpes simplex virus, anterior corneal dystrophies, recurrent erosions, granular dystrophy, and band keratopathy. Most patients received peribulbar anesthesia and underwent removal of the epithelium prior to laser ablation. A majority of patients had a reduction in the amount of corneal scarring and approximately half had improved visual acuity. No intraocular reaction or changes in endothelial counts were seen, and some patients avoided the need for penetrating keratoplasty. Reepithelialization usually occurred within 4 or 5 days and we noted no significant scarring secondary to use of the laser. It was difficult to eliminate preexisting irregular astigmatism despite the use of surface modulators, such as methylcellulose. A hyperopic shift secondary to corneal flattening was encountered in approximately 50% of the patients. A combination of myopic ablation, followed immediately by a secondary hyperopic steepening, may minimize this refractive change. The 193-nm excimer laser is an effective new tool in the treatment of selected patients with superficial corneal opacity from a variety of conditions.
The use of the 193-nm excimer laser for myopic photorefractive keratectomy in sighted eyes. A multicenter study.
Photorefractive keratectomy was performed at three centers using the 193-nm excimer laser on 31 sighted myopic eyes. Preoperative refractive errors (spherical equivalent) ranged from -12.00 to -4.00 diopters (D) (mean, -6.49 +/- 1.75 D). Peribulbar anesthesia, a 5.2- to 6.0-mm beam diameter, and topical corticosteroids were used for up to 6 months after surgery. The epithelium healed within 3 to 4 days, and all patients returned to their best corrected visual acuity within 1 line of their preoperative acuity. There was minimal subepithelial reticular haze, peaking at 3 weeks and diminishing over the next 3 to 4 months, which was not felt to be visually significant. At 6 months, the average residual refractive error was -1.85 +/- 2.5 D. Sixty-eight percent of eyes were corrected within 2 D and 55% within 1 D of attempted correction. There was no significant change in astigmatism, contrast sensitivity, corneal sensation, or endothelial cell counts. This preliminary work shows that photorefractive keratectomy has promise in the reduction of moderate myopia.
Modulation of catecholamine cardiomyopathy by allopurinol.
It has been suggested that cardiac injury by catecholamines may be the result of coronary constriction leading to ischemic damage. Allopurinol (ALLO) has been shown to reduce the extent of myocardial necrosis in various systems. Hence the possibility that ALLO might limit norepinephrine (NE) injury was tested. Rabbit hearts were infused with NE (3 micrograms/min/kg) for 90 minutes, with or without ALLO (50 micrograms/min/kg). Control specimens infused with saline solution plus ALLO were also prepared. Hearts were excised 48 hours later and studied as isovolumic isolated heart preparations. Peak systolic pressure, coronary flow, and myocardial oxygen consumption were significantly reduced in the hearts infused with NE but not in the NE + ALLO hearts. Myocardial adenosine triphosphate and glycogen concentrations were 29% and 26% lower in the NE hearts compared with control hearts. These reductions were absent in the NE + ALLO group. Moreover, rates of creatine phosphokinase and lactic dehydrogenase release were sharply elevated in the NE hearts but not in those also given ALLO. These findings are consistent with the changes observed histologically. The amount of myocardial damage was less in the ALLO + NE group compared with the NE group (p less than 0.02). This appears to be the first report to demonstrate that ALLO reduces myocyte damage by NE. Possible mechanisms include decreased free radical production, scavenging of free radicals, and preservation of the adenine nucleotide pool. Because xanthine oxidase activity is absent in the rabbit, the latter two mechanisms are more likely explanations for the findings.
Amelioration of hyperlipidemia by low fat diets in chronically streptozotocin-diabetic rats.
The effects of reduced dietary fat intake on plasma lipid levels were examined in diabetic rats. One week after induction of diabetes (D) with streptozotocin (65 mg/kg, iv), the animals were fed food pellets consisting of 1.5% (D1.5), 2.5% (D2.5) or 5% (D5) fat for two weeks. Irrespective of the diets, both food and water consumed by untreated diabetic rats were 2- to 5-fold greater respectively compared to normal. Plasma glucose concentrations were also similarly increased. Plasma and skeletal muscle lipid levels were significantly greater than controls in D2.5 and D5, but not in the D1.5 group. Plasma and muscle lipid concentrations correlated directly with fat consumption. In D5 rats receiving insulin treatment, plasma glucose and lipid concentrations were comparable to control values. These findings indicate that the degree of hyperlipidemia in chronically diabetic rats is directly related to dietary fat intake. They also demonstrate that dietary interventions can modulate some of the metabolic abnormalities in diabetes.
Use of the 193-NM excimer laser for myopic photorefractive keratectomy in sighted eyes: a multicenter study.
Explore the source record for details and available documents.