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Biomedical subjects

R Franklin

Publications and source records attributed to R Franklin.

66 records · Page 4Linked to original sources
PubMed1975

Hypercalcemia and tumor-prostaglandins: the VX2 carcinoma model in the rabbit.

The VX2 carcinoma produces profound hypercalcemia (17-22 mg/100 ml) in the rabbit about 3-4 wk after transplantation. A bone resorption-stimulation factor (assayed in vitro with mouse calvaria in culture) has been extracted with diethyl ether from the tumor tissue and from the medium of a clonal strain of VX2 cells grown in culture. Serologic methods reveal that the tumors contain 294 plus or minus 51 ng/g fresh weight (mean plus or minus SE, 25 tumors) of prostaglandin E2 (PGE2), a potent bone resorption-stimulating agent. VX2 cells in culture produce 0.5-3.0 mug PGE2 per mg cell protein per 24 hr. The production of bone resorption-stimulating activity and PGE2 by VX2 cells in culture were both inhibited by indomethacin (100 ng/ml). Tumors from normocalcemic, indomethacin-treated rabbits (10-40 mg/rabbit/24 hr) contained little or no bone resorption-stimulating activity nor PGE2. Tumor-bearing rabbits receiving indomethacin continuously did not develop hypercalcemia, however, following cessation of indomethacin administration, hypercalcemia developed rapidly and was again reversed by reinstitution of indomethacin feeding. In untreated, hypercalcemic, tumor-bearing rabbits, initiation of indomethacin treatment was followed by a rapid return of the plasma calcium to the normal range. Systemic venous plasma from hypercalcemic tumor-bearing plasma contained higher concentrations of PGE2 than plasma from normocalcemic control rabbits. Venous drainage of the tumor contained even higher plasma PGE2 concentrations than systemic venous plasma in hypercalcemic animals; plasma PGE2 concentrations locally and in systemic plasma were unmeasurable (less than 70 pg/ml) in normocalcemic, indomethacin-treated, tumor-bearing rabbits. We conclude that PGE2 is a bone resorption-stimulating factor produced by VX2 tumor cells, and that secretion of PGE2 by the tumor in vivo may well be responsible for the hypercalcemia observed in tumor-bearing rabbits.

Animals↗
PubMed1975

Comparison of honeybee venoms and their components from various sources.

The use of honeybee venoms and their components may assist in the elucidation of the pathophysiology of reactions to honeybee stings. This initial study compared venoms from various sources by chemical and biological assays, and significant variations were observed. Ten different bee venoms were compared by nitrogen analysis, mouse toxicity, hyaluronidase content, and antigenicity. Based on mouse toxicity, hyaluronidase content, and gel diffusion analysis, two groups of bee venoms could be differentiated. Venoms in one group, Group A, were more toxic, contained hyaluronidase, and showed an additional precipitin band. All venoms contained mellitin as a major fraction, which formed nonimmune precipitin bands during gel diffusion analysis. Gel filtration chromatography and dialysis separated the venoms into components that were then identified by enzyme assays, rat mast cell degranulation, hemolytic activity, and gel diffusion analysis. The venoms within Group A showed similar components, some of which, most noticeably hyaluronidase, were not present in Group B. Dialysis showed that a large portion of the venom could pass through a cellophane membrane including a portion of the phospholipase A. Heterogeneous molecular weights were found for phospholipase A by both gel filtration and dialysis, and may reflect variation in carbohydrate content. It appears that bee venom variability for whatever reason, a heterogeneous MW antigen, and a non-immune precipitable component require careful consideration in any study involving this venomm. These studies have yielded relatively pure, identified bee venom components which can be employed in further studies investigating reactions to honeybee stings.

Animals↗
PubMedDate not supplied

A randomized trial of nelfinavir, ritonavir, or delavirdine in combination with saquinavir-SGC and stavudine in treatment-experienced HIV-1-infected patients.

PURPOSE: To evaluate the 24-week impact of saquinavir-enhancing antiretroviral therapy on viral replication in patients previously treated with nucleoside analogues with or without prior saquinavir hard-gel capsules (HGC). METHOD: Patients were randomized in three groups to receive the following: Group 1-nelfinavir (750 mg tid), saquinavir soft-gel capsule (SGC) (800 mg tid), and stavudine (40 mg bid); Group II-ritonavir (400 mg bid), saquinavir-SGC (400 mg bid), and stavudine (40 mg bid); or Group III-delavirdine (400 mg tid), saquinavir-SGC (800 mg tid), and stavudine (40 mg bid). Viral loads, CD4 count, and safety were assessed over a 24-week period with an additional 6-month follow-up. RESULTS: 73 patients received randomized therapy; 14 of whom were SQV naïve, with a median baseline viral load of 3.6 log(10) and a CD4 count of 370 cells/mm(3). By 6 months, the median decreases in plasma viral loads were 0.26, 0.71, and 0.29 log(10) copies/mL for groups I, II, and III, respectively. The median increases in CD4 counts, for groups I, II, and III, were 52, 40, and 69 cells/mm(3) at 6 months, respectively. Changes in viral load and CD4 counts at 6 months and 1 year were not significantly different between the treatment groups. More patients discontinued therapy in the ritonavir arm (35%) for drug intolerance or toxicity compared to either the nelfinavir or delavirdine arms (15% and 5%, respectively). In a multivariate analysis, baseline viral load, younger age, and baseline saquinavir resistance were significantly associated with detectable viral load at 24 weeks. CONCLUSION: The use of antiretroviral agents that pharmacokinetically boost saquinavir levels has a modest benefit in saquinavir-experienced patients.

Adult↗