Modulation of Ca2+ levels in keratinocytes by all-trans retinoic acid.

Human epidermal keratinocytes, that have been growth-arrested by removal of epidermal growth factor from the culture medium, are stimulated to proliferate by all-trans retinoic acid (RA). The same treatment inhibits the onset of differentiated features and reduces cell-substrate adhesion. In the present study we show that the same treatment results in a decrease in total cell-associated Ca2+ as measured by changes in the amount of 45Ca2+ bound to cells at equilibrium following RA treatment and by a decrease in intracellular free Ca2+ levels as measured with the Ca(2+)-sensitive dye, Indo-1. The alterations in Ca2+ levels were evident within an hour after RA treatment, were in the range of 30-35% and occurred over the same RA concentration range that stimulated proliferation (i.e., 0.25-1.0 micrograms/ml). When the extracellular Ca2+ concentration was elevated from the normal level of 0.15-1.4 mM, intracellular free Ca2+ increased by a factor of 2 while total cell-associated Ca2+ increased approximately 6-fold. Even under conditions of high extracellular Ca2+, RA was able to reduce cell-associated and intracellular free Ca2+. These data indicate that RA has the capacity to lower Ca2+ levels in keratinocytes concomitantly with its effects on biological behavior.     

Treatment and survival of low-grade astrocytoma in adults--1977-1988.

A retrospective review of the records of the Division of Neuropathology at the New York University Medical Center between 1977 and 1988 revealed 53 cases of adult supratentorial astrocytomas. Fifty were fibrillary, and three were gemistocytic. Two additional patients had pilocytic tumors and were not included in the study. The majority of patients had either a subtotal (64%) or gross total resection (19%). Biopsy (17%) was performed for deep-seated lesions and for those lesions confined to eloquent cortex. Forty-eight patients (91%) received postoperative radiation therapy. The median survival was 7 1/4 years with a 5-year survival of 64%. Multivariate regression analysis demonstrated that the most important prognosticators for improved survival were young age, absence of contrast enhancement of the original tumor on computed tomography (CT) and the performance status of the patient. Patients with hemispheric tumors died from dedifferentiation into an anaplastic astrocytoma or a glioblastoma multiforme, with a median time to recurrence of 4.5 years from the original surgery. Survival from the time of recurrence was 12 months. Subsequent operations confirmed progression towards malignancy in six of seven (86%) recurrent tumors. CT contrast enhancement of the original tumor was associated with a 6.8-fold increase in risk for later recurrence. Patients with thalamic tumors (six patients) had a poor prognosis with a median survival of less than 2 years. A review of their CT scans suggest that four died of progressive low-grade disease; however, confirmatory autopsy data were available for only one patient. This study supports others that have shown improved survival for adult patients with astrocytomas treated in the CT era.     

Seroprevalence of HIV-1 and hepatitis B and C in prostitutes in Albuquerque, New Mexico.

A survey of persons soliciting sex in an area known to be frequented by prostitutes in Albuquerque, NM, included 43 females and 66 males. Seroprevalence rates found in this population-based study were as follows: human immunodeficiency virus type 1 (HIV-1), 3%; hepatitis B, 39%; hepatitis C, 45%. Increased age, intravenous drug use, and condom use were independent risk factors for hepatitis B. Female gender and intravenous drug use were independent risk factors for hepatitis C. Neither sharing injection equipment nor engaging in receptive anal intercourse was independently associated with hepatitis B or C.     

Effects of all-trans retinoic acid and Ca++ on human skin in organ culture.

In this study, we have established an organ culture model of human skin and examined the effects of both all-trans retinoic acid (RA) and extracellular Ca++ on the epidermal and dermal components of the organ-cultured skin. Our data show that while organ cultures maintained in serum-free, growth factor-free culture medium containing 0.15 mM Ca++ degenerated rapidly, those treated with concentrations of RA that have been shown previously to stimulate fibroblast and keratinocyte proliferation in monolayer culture (J Invest Dermatol 1989, 93:449; 1990, 94:717; Am J Pathol 1990, 136:1275) demonstrated a healthy appearance for up to 12 days. Degeneration of the control cultures was characterized by separation of the epidermis from the underlying dermis, progressive cell necrosis leading to a complete absence of viable cells from both the dermal and epidermal compartments, disintegration and fibrillation of the dermal connective tissue, and a cessation of protein synthesis. RA-treated organ cultures contained large numbers of healthy-appearing cells in both the epidermal and dermal compartments. One or several layers of viable basal cells in the epidermis could be seen at least through day 12. However, the upper layers of the epidermis frequently separated from the cells in the basal layer. The dermal connective tissue was histologically well-preserved. Furthermore, the level of protein synthesis was higher in the RA-treated cultures than in the control cultures. In addition to treating organ cultures with RA, other cultures were exposed to serum-free, growth factor-free culture medium containing 1.4 mM Ca++. The presence of the elevated Ca++ concentration also preserved cellular and connective tissue structures in the dermal and epidermal compartments. In comparison to RA there was better preservation of the overall epidermal structure. The upper layers of epidermal cells did not separate from the basal cells, and the various stages of epithelial differentiation could be seen. Histologically, the dermis was well-preserved in the presence of elevated extracellular Ca++. Specimens treated with a combination of Ca++ and RA demonstrated features consistent with the features induced by each treatment separately. This included an expanded basal layer of epithelial cells and a prominent keratotic layer with a fairly orderly pattern of differentiation. The tendency of the upper epidermis to separate from the basal cells was partially mitigated. Taken together, these data indicate that both RA and extracellular Ca++ act to prevent the degeneration of human skin in organ culture but probably do so through different mechanisms.     

Cyclosporine metabolism by P450IIIA in rat enterocytes--another determinant of oral bioavailability?

Cyclosporine is converted to its major metabolites (M-17, M-1, and M-21) in human liver by enzymes belonging to the P450IIIA subfamily. These enzymes are also present in rat and human enterocytes; however, the possibility that CsA is metabolized in enterocytes has not been previously investigated. We therefore directly compared metabolism of 3H-CsA in microsomes prepared from liver and jejunal enterocytes. M-17, M-1, and M-21 were the major CsA metabolites produced by enterocyte microsomes. This metabolism appeared to be catalyzed by P450IIIA, because pretreatment of rats with the P450IIIA inducer dexamethasone significantly increased the rate of CsA metabolism in enterocyte microsomes and preincubation of enterocyte microsomes with anti-P450IIIA IgG inhibited the production of CsA metabolites by greater than 95%. To determine if enterocyte P450IIIA metabolizes CsA in vivo, rats were pretreated with the P450IIIA inducer dexamethasone, the P450IIIA inhibitor erythromycin, or vehicle alone. At laparotomy, 2 mg/kg of 3H-CsA was injected into a sealed loop of jejunum, and after collection of the mesenteric venous blood draining this segment for 45 min, the production of M-17 and M-1 was measured. In the control group, a mean of 3.9% of the recovered radioactivity was found as M-1 and M-17. In the rats pretreated with dexamethasone, a mean of 8.4% of the radioactivity was found as M-1 and M-17 (P less than 0.05 relative to control) and this decreased to 2.3% in the group pretreated with erythromycin (P = 0.08 relative to control). We conclude that P450IIIA in jejunal enterocytes readily metabolizes CsA. Furthermore, the metabolism of CsA by enterocytes in vivo is substantial and likely contributes to "first pass metabolism" of orally administered CsA. Our observations provide novel hypotheses to explain some important drug interactions and interpatient differences in CsA dosing requirements.     

Immediate endoscopic diagnosis of upper gastrointestinal bleeding. Its accuracy and value in relation to associated pathology.

Two hundred sixty-two patients with active upper gastrointestinal (GI) bleeding underwent panendoscopy between July 1970 and March 1973. There was 100% accuracy of endoscopic diagnosis as to the anatomical site of bleeding; the etiopathologic definition was 94.7% accurate. The series was divided into two groups, 116 with "liver disease" and 146 with "no liver disease." There were 107 patients with varices: 21 fell into no liver disease (small varices) and 86 into liver disease (39 small and 47 large varices). All had associated gastritis. Three endoscopic bleeding patterns were identified in the liver disease group. Only 27% of the patients in the liver disease group with varices (cirrhotics) had frank variceal hemorrhage, whereas 57% bled from hemorrhagic gastritis. The diagnostic unit provided early diagnosis, meaningful therapy, organized data gathering, and rough estimates of ultimate prognosis.