Retinoids in the lateral eye of Limulus: evidence for a retinal photoisomerase

The lateral eyes of the horseshoe crab Limulus contain about 80 pmoles of retinal, 30 pmoles of retinol, and 4 pmoles of retinyl esters. More all-trans than 11-cis isomer was found in each category of retinoid. No consistent changes were observed in the amounts of retinal, retinol, or retinyl esters as a function of time of day. No 3,4-dehydro- nor hydroxyretinoids were found. Aqueous extracts of the eye support the stereospecific formation of 11-cis retinal from all-trans retinal when irradiated with light. The reaction requires a protein that is apparently recognized by polyclonal antibodies raised against the retinal photoisomerase extracted from honeybee eyes. The isomerase is able to use as substrate either endogenous all-trans retinal in the extract of retinal supplied in vesicles of phospholipid. The spectral efficiency of this isomerization has lambda max at 550 nm, but the spectrum appears too narrow compared with the absorbance spectrum of retinoid-binding proteins, probably because of inadequate correction for nonspecific isomerization at short wavelengths.

Commentary concerning demonstration of safety and efficacy of investigational anticancer agents in clinical trials

Expeditious clinical development and approval of new drugs that are beneficial to patients are matters of high priority. There has been a great deal of discussion within the oncology community about what should constitute evidence of effectiveness of new anticancer agents for purposes of drug approval. This commentary is intended to illustrate a variety of end points that can lead to approval of new anticancer agents for specific clinical situations. Although the ultimate hope of antineoplastic therapy is prolongation of life, there are other effects of anticancer drugs that constitute clear clinical benefit and represent evidence of effectiveness. The guiding principle is that the beneficial effects obtained from a new drug should sufficiently outweigh the adverse effects such that the potential risk:benefit ratio achieved by an individual patient is favorable. The assessment of a new drug should flexibly evaluate safety and efficacy in the context of the specific clinical condition being treated. Early discussions with the Food and Drug Administration (FDA) and the National Cancer Institute (NCI) are recommended to identify prospectively the end points and trial designs needed to demonstrate effectiveness of a new drug. The general principles discussed will likely apply to the drug approval process for other medical disciplines as well.

Thalamo-cortical processing of vibrissal information in the rat. I. Intracortical origins of surround but not centre-receptive fields of layer IV neurones in the rat S1 barrel field cortex

The receptive fields of cells restricted to the D1 cortical barrel territory in the S1 cortex of the rat were examined before and after substantial lesions of the D2 barrel. We tested 131 cells (N = 62, unlesioned controls; N = 69, lesioned animals) for modal latency and response magnitude to standard vibrissal deflections of 1.14 degrees. Lesions ranged in size to encompass 22-95% of the volume of the D2 barrel hollow and 5-75% of its neighbouring septal region, as calculated from cytochrome oxidase and Nissl staining of alternate sections. Negligible loss (mean 1.1%) of other barrel hollows and their septal regions (6.3%) occurred. A mean loss of 58% of the D2 barrel hollow and 27% of its accompanying septa was paralleled by a highly significant deficit in response magnitude (57.3%; p less than 0.005) of D1 barrel cells to D2 vibrissal stimulation, when compared with controls. The best-fit relationship between deficit and volumetric loss of the D2 barrel hollow was linear (regression coefficient -0.91). In the extreme case where 95% loss of D2 barrel hollow occurred, there was a 92% deficit in response of D1 barrel cells to the D2 input. No significant loss in response magnitude to other vibrissae, including the principal D1 input, occurred. Postlesioned animals exhibited some increase in excitability to the D1 vibrissa, and to vibrissae whose principal barrel territories were undamaged (delta, gamma, C1). Lesioning of the D2 barrel caused a highly significant mean increase (60%) in latency of residual responses to stimulation of the D2 vibrissal input (15.2 ms controls; 24.3 ms experimentals). No significant changes in response latency to other vibrissae compared to controls occurred. These results suggest that an intact D2 barrel is essential for the generation of responses of D1 barrel cells by the D2 vibrissa, and further imply that surround receptive fields of layer IV barrel cells are largely generated intracortically by barrel-to-barrel relay. The implications of these findings to cortical processing of tactile information and plasticity in the somatosensory system are discussed.

Opportunities in clinical trials. Adjuvant breast cancer

Breast cancer is the most common cancer in women in the US, with approximately two-thirds of patients presenting with tumors confined to the breast alone or breast and ipsilateral axillary lymph nodes. Although all of these women can be rendered free of detectable breast cancer by local therapeutic modalities, many will experience recurrences regionally or at distant sites. Nearly all patients who have distant recurrences will subsequently die of breast cancer. Although metastatic breast cancer responds to a variety of hormonal and chemotherapeutic interventions, it is rare that such therapy is curvative. Hence, there has been great interest in studying adjuvant systemic therapies. There is now a long clinical trial experience with adjuvant therapy in breast cancer that provides an extensive background for implementing recent advances in molecular and cellular biology in the clinical setting. Predictably, these laboratory-clinical correlations will provide important leads for future generations of randomized adjuvant trials, both by helping to target new therapies for particular subsets of patients and by identifying prognostic groups. In this report, current efforts in adjuvant therapy trials and laboratory-clinical correlations being conducted in conjunction with those trials are described.

The distribution of [14C]acrylamide in rainbow trout studied by whole-body autoradiography

The distribution of [2,3-14C]acrylamide was studied in fingerling rainbow trout by whole-body autoradiography. Fish weighing approximately 7 g were injected ip with 3.2 mg/kg [14C]acrylamide (0.1 microCi/g). One group of fish was kept in a fresh flowing water tank and frozen in dry ice/hexane 22 hr after injection; another group was placed in a separate tank of fresh flowing water and frozen 120 hr after treatment. A third group of fish served as nontreated controls. The autoradiographs of the fish at 22 hr show the highest concentration of radioactivity in the kidney, urinary bladder, blood, gallbladder, intestinal contents, and lens of eye. Lesser amounts of radioactivity are seen in the CNS, liver, and gills. Very low concentrations are seen in muscle. By 120 hr the only high concentrations are seen in gallbladder and lens of the eye. Lesser amounts are seen in the sclera, vertebrae, CNS, kidney, wall of intestine, and discrete spots in subcutaneous tissue presumed to be chromatophores. Low amounts are seen in muscle, the tissue usually consumed by man.

A randomized trial of continuous intravenous versus hepatic intraarterial floxuridine in patients with colorectal cancer metastatic to the liver: the Northern California Oncology Group trial

In 1983, the Northern California Oncology Group (NCOG) instituted a randomized trial of intravenous (IV) versus intraarterial (IA) floxuridine (FUDR) administered via an implantable pump for patients with colorectal cancer metastatic to the liver. The study objectives were to compare the hepatic response rate, time to hepatic progression, and toxicity for the two treatment arms. The study design, which allowed patients failing IV FUDR to crossover to the IA arm, prevents a meaningful comparative analysis of survival. Patients with liver-only metastases (N = 143) were randomized, 76 to the IV arm and 67 to the IA arm, and 115 patients (65 IV, 50 IA) were fully evaluable. Of the 65 patients in the IV arm, 28 crossed over to IA treatment after failing IV FUDR. The dose-limiting toxicity of IV FUDR was diarrhea, whereas biliary toxicity limited both the dose and duration of IA FUDR therapy. Of the first 25 patients treated with IA FUDR at a dose of .3 mg/kg/day, 10 developed radiographically evident biliary strictures, and three developed permanent jaundice. With reduction of the initial IA FUDR dose to .2 mg/kg/day, and adoption of a policy of early dosage reduction, treatment interruption, or termination of therapy for persistent elevations in alkaline phosphatase, only two further cases of serious biliary toxicity occurred. However, 26 of the 50 IA FUDR patients ultimately had therapy terminated because of drug toxicity rather than disease progression. When compared with systemic infusion, infusion into the hepatic artery greatly enhanced the antitumor activity of FUDR against colorectal liver metastases. Although biliary toxicity is the most serious limitation of this form of therapy, biliary stricture and jaundice usually can be averted through careful monitoring of liver enzymes and early dosage reduction.

Treatment of patients with advanced colorectal carcinomas with fluorouracil alone, high-dose leucovorin plus fluorouracil, or sequential methotrexate, fluorouracil, and leucovorin: a randomized trial of the Northern California Oncology Group

We compared the effectiveness of fluorouracil (5-FU) alone (arm A), high-dose leucovorin plus 5-FU (arm B), and sequential methotrexate, 5-FU, and leucovorin (arm C) for treatment of patients with advanced colorectal carcinomas who had not received prior chemotherapy. Arm A consisted of infusions of 5-FU at 12 mg/kg/d intravenously (IV) for 5 days followed by weekly infusions of 5-FU at 15 mg/kg; arm B consisted of leucovorin infusions at 200 mg/m2/d IV plus infusions of 5-FU at 400 mg/m2/d IV on days 1 through 5 of a 28-day cycle; arm C consisted of methotrexate at 50 mg/m2 orally every 6 hours for five doses followed by infusions of 5-FU, 500 mg/m2 IV, and leucovorin, 10 mg/m2 orally, every 6 hours for five doses every other week. A total of 265 patients were entered into the trial, of whom 249 (94%) were fully evaluable. The objective response rate (complete [CR] plus partial [PR] responses) was 17.3% on arm A, 18.8% on arm B, and 19.8% on arm C (log-rank test, P greater than .4). The median time to failure was 138 days on arm A, 166 days on arm B, and 182 days on arm C (log-rank test, P values of arm A v B = .06; arm A v arm C = .04). Median survival was 345 days on arm A, 324 days on arm B, and 356 days on arm C (log-rank test, P greater than .4). Treatment with 5-FU alone was significantly more dose intensive and more toxic than either of the experimental combinations. The rates of grade 3 or greater nonhematologic toxicity were 42.3% on arm A, 24.3% on arm B, and 14.3% on arm C. Hematologic toxicity was milder but had the same pattern. This study indicates that these regimens of high-dose leucovorin plus 5-FU and sequential methotrexate, 5-FU, and leucovorin are not more effective than is 5-FU alone for treatment of patients with colorectal carcinomas when 5-FU is administered at high-dose intensity.

Adjuvant multimodality treatment of rectal cancer

It has long been recognized that curative surgery as the sole treatment for rectal cancer yields disappointing results. There is now a growing body of evidence from prospective randomized clinical trials to support the role of adjuvant therapy for patients whose primary tumour has spread through the rectal wall or has associated lymph node involvement. Carefully planned radiation therapy with adequate doses and fields can reduce the risk of locoregional failure. Chemotherapeutic agents delivered either systemically or regionally may also contribute to better disease control and survival. A number of diagnostic and therapeutic issues still need to be addressed in order to use the available adjuvant treatment methods most appropriately. Efforts to refine patient selection, to enhance therapeutic effect and to minimize toxicity are likely to improve the outlook for patients with resectable rectal cancer.

Locally advanced breast cancer current status and future directions

Patients described as having locally advanced breast cancer comprise a heterogeneous group of patients with variable clinical presentations. Systematic evaluation of patients with these presentations has been limited, with much of our current understanding based on retrospective reviews. Prospective pilot studies have demonstrated the feasibility of multimodality therapy. However, there have been few well-conducted randomized trials in this setting. Comparison of results among studies is made difficult by the varying eligibility criteria and the way in which the data are reported. The use of common and consistent definitions of operable and inoperable disease is necessary for a more uniform understanding of the therapeutic interventions necessary for a given patient within this broad category of Stage III or locally advanced breast cancer. There are a variety of opportunities for clinical research activities in this group of patients including tests of hormonal recruitment or synchronization, high dose chemotherapy requiring autologous bone marrow transplantation, perioperative or preoperative chemotherapy, and alternating chemotherapy with short course radiotherapy. The integration of clinical information with biological characteristics of the tumor such as cytokinetics, oncogene amplification, and hormone receptors will be an important and necessary focus of future investigation in this disease.

Three-generation reproduction study with caprolactam in rats

In a three-generation reproduction study, rats were given caprolactam in the diet of 0, 1000, 5000 and 10,000 ppm. No treatment-related effects were observed in the parental animals with respect to mortality, clinical signs, reproductive performance or gross pathology findings. Consistently lower body weights were noted in the P2 and P3 mid- and high-dose males and females. Consistently lower mean food consumption values were noted in the P2 and P3 mid- and high-dose males and the high-dose females. These differences were generally significant (P less than or equal to 0.05) in the high-dose group of both sexes. Compound-related histopathologic findings noted in the high-dose P1 males consisted of a slight increase in the severity of spontaneous nephropathies, occasionally accompanied by granular casts. The offspring data revealed no treatment-related effect with respect to gross appearance, gross pathology, survival, number of pups, percentage of male pups or kidney weight. Analysis of the offspring body weights on Days 1, 7 and 21 of lactation revealed consistently and generally significant lower mean values in the high-dose male and female animals of all filial generations. The mean body weights of both sexes in the mid-dose group were generally lower than those of the controls. The effects on mean body weight, mean food consumption and the group increases in the severity of nephropathy, accompanied by the presence of granular casts in some animals, are considered to be related to the administration of caprolactam.

Surgical oncology research. A disappointing status report

The purpose of this paper is to evaluate certain aspects of the present status of surgical oncology research. We have attempted to define the magnitude of the problem, characterize features unique to the surgical community, and formulate potential solutions. Demographic data concerning grant applications submitted to and funded by the National Cancer Institute (NCI) over the time period from 1980 to 1985 were analyzed. Departments of surgery submitted and were awarded substantially fewer grants over the study period than departments of medicine. Additionally, the number of applications submitted from departments of medicine increased during this time period while those from departments of surgery declined. This record is particularly worrisome because it occurred during a period of time of unprecedented scientific and educational opportunities and support mechanisms provided by the NCI. Further conclusions and potential solutions are discussed in this paper.

Combined radiotherapy and chemotherapy with bleomycin and methotrexate for advanced inoperable head and neck cancer: update of a Northern California Oncology Group randomized trial

Between 1978 and 1984, the Northern California Oncology Group (NCOG) conducted a randomized trial to study the efficacy of combined radiotherapy (RT) and chemotherapy (CT) for stage III or IV inoperable head and neck cancer. One hundred four patients were randomized to receive: (1) RT alone, or (2) RT plus CT. RT consisted of 7,000 cGy to the involved areas and 5,000 cGy to uninvolved neck at 180 cGy/fraction, five fractions/wk. CT consisted of bleomycin, 5 U intravenously (IV), twice weekly during RT, followed by bleomycin, 15 U IV, and methotrexate, 25 mg/m2 IV weekly for 16 weeks after completion of RT. Fifty-one patients in the RT alone group and 45 in the combined treatment group were evaluable. The local-regional complete response (CR) rate was 45% v 67% (P = .056); the 2-year local-regional control rate, including salvage surgery, was 26% v 64% (P = .001); and the incidence of distant metastasis was 24% v 38% (P greater than .25), for the RT alone and RT plus CT groups, respectively. The relapse-free survival curves were significantly different (P = .041), favoring the combined treatment. However, the survival curves were not significantly different (P = .16). Patient compliance to maintenance CT was poor. Bleomycin significantly increased the acute radiation mucositis, although the difference in late normal tissue toxicity was not statistically significant. Thus, bleomycin and concurrent RT produced a more favorable CR rate, local-regional control rate, and relapse-free survival, but the difference in survival was not statistically significant.