Characteristics of rejection of orthotopic corneal allografts in the rat

We have employed a rat model of orthotopic corneal transplantation to study the characteristics of rejection and development of systemic immunity in the host. Lewis (LEW) rats underwent a true penetrating keratoplasty using Wistar-Furth (WF) donor corneas. A rejection incidence of 55% with a mean survival time (MST) of 17.1 days was observed using these untreated allogeneic corneas. Animals undergoing rejection of these allografts developed cytotoxic T lymphocytes (CTL) capable of lysing WF lymphoblasts in a standard 51-chromium release assay. These same rats did not have delayed-type hypersensitivity (DTH) responses when compared to skin grafted controls. Rats with clear allografts had no demonstrable CTL or DTH activity. As expected, LEW rats that were preimmunized with WF skin grafts and subsequently received WF orthotopic corneal grafts rejected 100% of these corneas at an accelerated rate (MST = 9.7 days, P less than .02). We then employed a previously described technique of using latex beads to induce migration of Langerhans cells into the central cornea of the donor graft prior to transplantation. The presence of Langerhans cells in the donor cornea resulted in a higher incidence of rejection (96%) and an accelerated rate (MST = 11.8 days, P less than .02) when compared to untreated allografts. These rats also had a higher level of CTL activity and marked DTH responses. These data show that rejection of orthotopic allogeneic corneas is accompanied by the development of systemic alloimmunity as measured by CTL activity. However, these fully allogeneic corneas can be rejected in the absence of DTH responses. Langerhans cells have a dramatic effect on graft survival and are necessary for induction of DTH responsiveness in the host.     

Response of Orbital and Central Nervous System Metastases of Retinoblastoma Following Treatment with Cyclophosphamide/Doxorubicin

A 3.5-year-old boy with orbital and central nervous system extension of unilateral retinoblastoma received chemotherapy consisting of intravenous cyclophosphamide and doxorubicin and intrathecal methotrexate. Complete shrinkage of orbital tumor, phthisis bulbi,'and disappearance of intracranial metastases occurred following chemotherapy. Response of the intra-cranial tumors reflected the combined effects of cyclophosphamide and doxorubicin; the contribution of each agent could not be assessed. Cerebrospinal fluid tumor cells persisted prior to delivery of craniospinal irradiation, and were detected again 6 weeks after completion of irradiation.     

Rapid characterization of mutagenic aromatic amines in energy-related materials by short column liquid chromatography with electrochemical detection

A liquid Chromatograph equipped with a short (3 cm) reverse phase column and electrochemical detector was used to characterize aromatic amines in shale oil, synthetic oil, and coal gasification streams. Five major peaks were produced from each sample mixture. The composition of the peaks was determined by high performance liquid chromatography with a long (25 cm) reverse phase column and by gas chromatography/mass spectrometry. Amines in the various peaks included aminonaphthalenes, aminobiphenyls, aminofluorenes, and aminophenanthrenes plus aminoanthracenes. The concentration of aminofluorenes, and aminophenanthrenes plus aminoanthracenes correlated with relative mutagenicity of the base fraction from the oils or tars. The levels of 2- and 3-ringed aromatic amines from shale oil and oil from the Great Plains commercial coal gasification plan were 24 and 184 g/g tar, respectively, while the respective mutagenicities were 8 and 214 revertants/g base fraction. This technique has the advantages of high sensitivity and rapid analysis, and could be used to screen for the presence of mutagens in synthetic fuel samples.     

Effect of dipyridamole on fluorodeoxyuridine cytotoxicity in vitro and in cancer patients

Summary Dipyridamole (DP) has previously been studied both in vitro and in vivo in combination with various antimetabolites, including methotrexate and 5-fluorouracil (5FU). We evaluated in vitro and clinically the effects of adding DP to fluorodeoxyuridine (FUDR) in colorectal cancer. Using a human colony-forming assay, we observed that 0.05 M DP increased the cytotoxicity of FUDR by a median of 33.5-fold vs 1.5-fold for 5FU against human colon-cancer cell lines. The mechanism of the DP-enhanced antitumor activity of FUDR is not completely understood but appears to be related to a profound inhibition by DP of thymidine accumulation in and FUDR efflux from colon-cancer cell lines. On the basis of these in vitro results, 28 patients with metastatic colon cancer were entered in a clinical trial of monthly courses of 0.1 mg/kg FUDR daily for 14 days and 75 mg oral DP 5 times daily for 14 days starting on the 3rd day of continuous i.v. FUDR infusion. The pharmacokinetics of DP was studied in three patients; the results showed that 98% of total serum DP was protein-bound and that free DP levels were significantly lower than the concentrations necessary for the expected in vitro DP/FUDR modulation. Treatment was well tolerated, with only 12 patients developing mild to moderate toxicity. Of 27 evaluable patients, 4 achieved a partial response that lasted 2, 3, 5, and 6+ months. This relatively low response rate (15%), which is similar to that achieved with FUDR alone, may be explained by the low steady-state plasma concentrations of free DP achieved in our patients. Other means of DP administration, such as i.v., i.a., and i.p. injection, may be required to achieve free DP concentrations necessary for successful biochemical modulation of FUDR in patients.Supported in part by grants CA17094, CA23074, and CA39629 from the National Institutes of Health, Bethesda, Md 20205, and a grant from the Arizona Chronic Disease Commission. HSG is a recipient of an American Cancer Society Career Development Award     

Detailed gene copy number and RNA expression analysis of the 17q12-23 region in primary breast cancers

Chromosome region 17q12-23 commonly shows an increase in DNA copy number in breast cancers, suggesting that several oncogenes are located at this site. We performed a high-resolution expression array and comparative genomic hybridization analysis of genes mapped to the entire 17q12-23 region, to identify novel candidate oncogenes. We identified 24 genes that showed significant overexpression in breast cancers with gain of 17q12-23, compared to cancers without gain. These genes included previously identified oncogenes, together with several novel candidate oncogenes. FISH analysis using specific gene probes hybridized to tissue arrays confirmed the underlying amplification of overexpressed genes. This high-resolution analysis of the 17q12-23 region indicates that several established and novel candidate oncogenes, including a Wnt-signaling pathway member, are amplified and overexpressed within individual primary breast cancer samples. We were also able to confirm the presence of two apparently separate and reciprocally amplified groups of genes within this region. Investigation of these genes and their functional interactions will facilitate our understanding of breast oncogenesis and optimal management of this disease.     

Role of RNA and protein in memory storage: A review

The literature on the possible role of RNA and protein in long-term memory is reviewed in terms of the following five criteria: (1) The molecule should have a defined role in normal brain function. (2) There should be a quantitative and/or qualitative change in the molecule as a function of learning. (3) The molecule should lead to some type of relatively permanent change in the functioning of the brain. (4) Altered synthesis or utilization of the molecule should lead to predictable consequences for memory. (5) The localization of the response should be consistent in terms of the utilization of that portion of the brain in the particular task.     

Enhanced cerebrovascular permeability by Metrazol: significance for brain metastases

Metrazol enhanced the penetration of two proteins (¹²⁵I human serum albumin and horseradish peroxidase), and the anticancer agent, razoxane, into the central nervous system of anaesthetized rats. Penetration was increased throughout the whole brain. With the exception of the bladder, no peripheral tissue was affected. The increase in brain permeability was temporary and reversed within 4 hours; brain levels of drug and protein were increased by up to three times.[/p]