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Biomedical subjects

K Chen

Publications and source records attributed to K Chen.

At least 559 records · Page 31Linked to original sources
PubMed1975

Comparison of physical and immunological properties of plasma membranes of two mouse leukemia cell lines, P388 and L1210.

A method for the isolation of the plasma membranes of the mouse leukemic cell P388 is described. The method includes surface labeling of the cell membrane with 125I. The 125I specific activity of the plasma membrane preparation is 10- to 13-fold higher than that of the cell homogenate; enzyme assays and electron microscopy further corroborate the purity of the P388 plasma membrane preparation. The predominant iodinated membrane proteins have molecular weights of 85,000, 66,000, and 13,000 daltons. Antibodies prepared against P388 and L1210 plasma membranes inhibit the growth of the corresponding cells in the absence of complement. They show cross-reactivity to each other but do not affect the growth of HeLa cells.

Alkaline Phosphatase↗
PubMedDate not supplied

NMDA receptor-blocker ketamine protects during acute carbon monoxide poisoning, while calcium channel-blocker verapamil does not.

Levine-prepared, female, Sprague-Dawley rats were used to investigate the possible protective effects of the NMDA receptor-blocker anesthetic ketamine and the Ca2+ channel-blocker verapamil (0.4 mg kg-1 'low dose', and 1.0 mg kg-1 'high dose') in rats during acute 2400 ppm carbon monoxide (CO) poisoning. Blood glucose and lactate concentrations, heart rate, mean arterial blood pressure (BP), body temperature (BT), neurological function and cerebral cortical water content were measured. In most cases glucose increased after 45 min and then fell to initial values after 90 min. Lactate concentration increased sharply during CO exposure in the saline and in the low- and high-dose verapamil groups, while the lactate increase in rats given ketamine at 40 mg kg-1 was significantly lower than with saline. Lactate was also significantly lower in these rats after 90 min than in the high-dose verapamil group. Lactate was normal in all four groups after 2 and 4 h of air recovery. Ketamine significantly lowered the heart rate prior to CO exposure, and the heart rate remained significantly below values for the saline and for the low- and high-dose verapamil groups throughout CO exposure. The BP decreased in all groups during CO exposure, and the BP recovery which took place in all four groups was significantly more rapid in the ketamine group. Recovery from CO-induced hypothermia was similar in the ketamine and saline groups, whereas rewarming tended to occur more slowly and less completely in the two verapamil-treated groups. There were no significant differences in neurological function among the four groups, as assessed after 4 h of recovery. However, cerebral edema was significantly reduced by treatment with 40 mg kg-1 ketamine as compared with saline. Verapamil at neither the low nor the high doses was of significant benefit in this regard. No rat in the 40 mg kg-1 ketamine group died during CO exposure, whereas all deaths in the other groups took place during CO exposure. The use of higher and lower doses of ketamine suggest 40-80 mg kg-1 as most effective in suppressing lactate production; 40 mg kg-1 ketamine may be optimal with regard to survival. The results suggest that ketamine is beneficial, when administered before and during acute severe CO poisoning, in reducing blood lactate and cerebral edema and in improving BP recovery and survival. Verapamil, in contrast, appears to provide no benefits in these respects.

Animals↗
PubMedDate not supplied

T-cell markers in tumor-infiltrating lymphocytes of head and neck cancer.

Fresh suspensions of tumor-infiltrating lymphocytes (TIL) from 16 patients with squamous cell carcinoma of the head and neck (SCCHN) were examined for T-cell markers including CD4 (helper-inducer), CD8 (cytotoxic-suppressor), natural killer (NK) cell, and activation surface markers using monoclonal antibodies and two-color flow cytometry. Two of 8 (25%) patients with a CD4/CD8 ratio of less than 1 developed cervical lymph node metastases; none had extracapsular spread. Six of 8 (75%) patients with a CD4/CD8 ratio of greater than 1 developed cervical metastases; 5 of 6 (83%) exhibited extracapsular spread. An increased CD4/CD8 ratio was attributable to a decrease in CD8+ cells. A CD4/CD8 ratio of greater than 1 may be a useful prognostic indicator of the development of cervical metastases.

Adult↗
PubMedDate not supplied

Three-month comparison of bimatoprost and latanoprost in patients with glaucoma and ocular hypertension.

A multicenter, randomized, investigator-masked, parallel-group trial compared bimatoprost and latanoprost for efficacy and safety in patients with glaucoma or ocular hypertension. Patients received bimatoprost 0.03% (n = 119) or latanoprost 0.005% (n = 113) once daily in the evening for 3 months. Visits were at prestudy, baseline (day 0), week 1, and months 1, 2, and 3. Primary outcome measures were mean IOP and the percentage of patients achieving IOP of 17 mm Hg or lower at 8:00 AM. Secondary outcome measures were diurnal IOP measurements (8:00 AM, 12 noon, 4:00 PM, 8:00 PM) at month 3 and safety measures including adverse events. Mean IOP was lower with bimatoprost than with latanoprost at all time points during the 3-month follow-up, although the between-group difference was not always statistically significant. At month 3 at 12 noon, mean IOP was as much as 1.0 mm Hg lower with bimatoprost (P = .021). Target pressures of < or = 17 mm Hg were reached more often with bimatoprost than with latanoprost at 8:00 AM (53% vs 43%; P = .029). Over all diurnal measurements at month 3, low target pressures of < or = 13, < or = 14, and < or = 15 mm Hg were achieved significantly more often with bimatoprost (P < or = .006). Both drugs were safe and well tolerated. Conjunctival hyperemia was more common with bimatoprost, while headache was more frequent with latanoprost. Bimatoprost provided lower mean pressures than latanoprost at every time point throughout the study and was statistically superior in achieving low target pressures. More patients reached low target pressures with bimatoprost.

Amides↗
PubMedDate not supplied

Photodynamic therapy using SnET2 for basal cell nevus syndrome: a case report.

A 26-year-old man with basal cell nevus syndrome presented to the Rocky Mountain Cancer Center (Denver, Colorado) for treatment of several basal cell carcinomas with photodynamic therapy using tin ethyl etiopurpurin (SnET2). The patient was of northern European descent, had type I skin (always burns, never tans), and had a 10-year history of multifocal basal cell carcinomas. The patient had a family history of Gorlin's syndrome (basal cell nevus syndrome); the syndrome had been diagnosed in this patient in 1985. The patient was enrolled in a Phase I/II clinical trial. He was given 1.2 mg/kg (94 mg total) of SnET2 via intravenous infusion; he returned to the clinic the following day for red light application. Thirteen lesions, in 12 treatment fields, were illuminated with light totaling 200 J/cm2 at a fluence of 150 mW/cm2. At the 3-month follow-up examination, all tumors were graded as having a complete response by modified AIDS Clinical Trial Guidelines oncologic standards. No evidence of recurrence has been noted during the 6-month follow-up period.

Adult↗
PubMedDate not supplied

Acute thoracic aortic dissection: the basics.

With an increasing incidence, aortic dissection is the most common acute illness of the aorta. In the setting of chronic hypertension, with or without other risk factors for aortic dissection, this diagnosis should be considered a diagnostic possibility in patients presenting to the emergency department with acute chest or back pain. Left untreated, about 75% of patients with dissections involving the ascending aorta die within 2 weeks of an acute episode. But with successful initial therapy, the 5-year survival rate increases to 75%. Hence, timely recognition of this disease entity coupled with urgent and appropriate management is the key to a successful outcome in a majority of the patients. This article reviews acute thoracic aortic dissection, including ED diagnosis and management.

Acute Disease↗
PubMedDate not supplied

Malignant airway obstruction: recognition and management.

Malignant airway obstruction affects up to 80,000 patients annually, many of whom will present acutely to the emergency department (ED). This clinical entity should be sought in any patient presenting to the ED with increasing shortness of breath, recurrent chest infections, hemoptysis, and an inability to lie flat. Interventions suggested in malignant airway obstruction include: maintenance of spontaneous ventilation by avoiding respiratory depressing sedation, muscle relaxants or narcotics; changes in patient's position; avoidance of general anesthesia and positive pressure ventilation, if possible; placement of endotracheal tube beyond the level of obstruction; radiotherapy; corticosteroids; availability of helium-oxygen mixtures, cardiopulmonary bypass, or extracorporeal membrane oxygenation. If time allows, further diagnostic studies will be of assistance in assessing the best therapy before definitive intervention.

Airway Obstruction↗