Presentation of the rous-whipple award to morris j. Karnovsky-1981

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Reconstructive surgery of the mental canthal region

The complexity of the medial canthal area is discussed and the importance of complete tumor removal with microscopically controlled excision emphasized.. Immediate reconstruction is recommended in most instances. Defects to be reconstructed are divided into nasal and eyelid sides of the medial canthal region and subdivided into superficial and deep defects. The reconstructive modalities used in the various defects are illustrated and the advantages and disadvantages of each explored.

Presidential address. Recent concepts of initiation and promotion in carcinogenesis

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Presentation of the Warner-Lambert Parke-Davis award to Dr. Michael W. Lieberman

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Inhibition of spontaneous hepatocarcinogenesis in C3H/HeN mice by transplanted hepatocellular carcinomas

Cell suspensions of tumor fragments derived from spontaneous or chemically induced primary hepatocellular carcinomas obtained from inbred C3H/HeN mice were transplanted into young male mice of the same strain. Transplantable hepatocellular carcinomas were excised as soon as they were detected, and all recipient mice were killed at one year of age. In control C3H/HeN mice, the incidence of primary hepatocellular carcinomas was 41% (41 of 100). In mice in which there was no growth of transplantable carcinomas, whether originally given injections of tumor cell suspensions or fragments, the overall incidence of primary hepatocellular carcinomas was 49% (35 of 72) with one to six tumors per liver at time of sacrifice. Transplantable hepatocellular carcinomas were established only in mice that had received tumor fragments. In these mice, from which established transplantable hepatocellular carcinomas had been excised, the overall incidence of primary hepatocellular carcinomas was 12% (3 of 25) with one tumor being found in each of three livers. The time of appearance of excision of transplantable hepatocellular carcinoma did not affect this decrease in primary hepatocellular carcinoma incidence.

Fibronectin production by human mammary cells

Human mammary cells were examined for the presence of the high-molecular-weight surface glycoprotein fibronectin. Early passage mammary epithelial cell and fibroblast cultures from both carcinomas and normal tissues were tested for the presence of cell-associated fibronectin by immunofluorescence microscopy and for the synthesis and secretion of fibronectin by specific immunoprecipitation of metabolically labeled protein. In vivo frozen sections of primary carcinomas and normal tissues were tested for the localization of fibronectin by immunofluorescence microscopy. In contrast to the extensive fibrillar networks of fibronectin found in the fibroblast cultures, the epithelial cell cultures from both tissue sources displayed a pattern of cell-associated fibronectin characterized by powdery, punctate staining. However, the cultured epithelial cells, as well as the fibroblasts, secreted large quantities of fibronectin into the medium. Putative myoepithelial cells also displayed extensive fibrillar networks of fibronectin. The difference in cell-associated fibronectin distribution between the epithelial cells and the fibroblasts and putative myoepithelial cells provided a simple means of quantitating stromal and myoepithelial cell contamination of the mammary epithelial cells in culture. In vivo, normal tissues showed fibronectin primarily localized in the basement membrane surrounding the epithelial cells and in the stroma. Most primary carcinomas displayed powdery, punctate staining on the epithelial cells in addition to the fibronectin present in the surrounding stroma.

Alterations in polyadenylated messenger ribonucleic acid from free and total polysomes of a rat hepatoma

We examined the homology between polysomal polyadenylated ribonucleic acid (mRNA) populations of hepatoma 252, a tumor which is deficient in the synthesis of plasma proteins, and those of normal and regenerating rat liver. Hybridization of polyadenylated mRNA populations with homologous or heterologous complementary deoxyribonucleic acids showed that mRNA from total and free polysomes from hepatoma 252 lack sequences which are present in normal or regenerating liver. Although there are obvious differences in the abundance of sequences between tumor and normal or regenerating liver polysomal mRNA, we did not detect, with the techniques used in this work, tumor-specific sequences. Analysis of hybridization curves using derivative plots did not reveal the presence in tumor mRNA of a high complexity class not present in normal liver. We conclude that alterations in mRNA populations of free and total polysomes of this tumor primarily reflect processes of genetic restriction rather than the derepression of previously unexpressed genes.

Differential inhibition of rat liver DNA polymerases in vitro by direct-acting carcinogens and the protective effect of a thiol reducing agent

The direct-acting carcinogens acetoxyacetylaminofluorene, methylnitrosourea, and N-methyl-N'-nitro-N-nitrosoguanidine were tested for their ability to inhibit rat liver DNA polymerase-alpha, -beta, and -gamma activity in vitro. DNA polymerase-alpha was the most sensitive, polymerase-beta was the most resistant, and polymerase-gamma exhibited an intermediate response. When the reactions were reassayed in the presence and absence of dithiothreitol, a thiol reducing agent, it was shown that the inhibition by carcinogens was generally reversible with increasing dithiothreitol, except that polymerase-beta recovered only 80-90% of control values. These and binding data suggest that DNA polymerase-beta, the putative repair enzyme, is highly resistant to carcinogen damage. This resistance may contribute to the retention of normal function and fidelity of the repair enzyme during carcinogen exposure in vivo and to a normal cellular repair.

DNA methylation and methylase levels in normal and malignant mouse hepatic tissues

The status of DNA methylation, as measured by the 5-methylcytosine content of nuclear DNA, was examined in normal livers and in chemically induced or spontaneous primary hepatocellular carcinoma (PHC) arising in three strains of mice. The DNA from spontaneous tumors of genetic origin in C3H mice and also from acetylaminofluorene, chlordane, or 3'-methyl-4-dimethylaminoazobenzene-induced tumors in C57Bl and B6C3 mice was undermethylated compared to the levels in background and normal liver samples. The DNA methylase activities from normal liver, background liver, and PHC were assayed in C3H mice to determine whether the observed genomic undermethylation is related to a dysfunction of this enzyme and were compared to the rates of DNA synthesis in these tissues. Since DNA methylase levels from tumor nuclei were elevated compared to background, it is concluded that the undermethylation found in the tumor genomes of this system is not due to inactivation nor a significant deficiency of the activity of this enzyme relative to the demand in tumors for methylation of de novo synthesized DNA.

Chromatin conformation modulates repair of single strand interruptions by polynucleotide ligase-[3H] AMP

Conformationally distinct chromatin populations were utilized as substrates to quantitate the relative amount of and accessibility of internal 5'-phosphomonoester breaks in DNA-chromatin. In these studies, a constant amount of chromatin as well as deproteinized DNA derived from the respective chromatin sample was titrated with increasing quantities of adenylated polynucleotide ligase intermediate. This enzyme intermediate releases its AMP moiety while repairing a DNA single strand interruption, release of AMP being directly proportional to the number of internal 5'-phosphomonoester breaks repaired. Results of this study indicate that the ability of polynucleotide ligase to repair DNA breaks within chromatin was affected by the conformational state of the chromatin. The degree of conformational constraint present in a given chromatin, therefore, determined the capacity of the enzyme to repair internal DNA 5'-phosphomonoester breaks.

Decreased fidelity in one subspecies of DNA polymerase-alpha that appears during N-2-acetylaminofluorene hepatocarcinogenesis

During the exposure of rat livers to the hepatocarcinogen 2-acetylaminofluorene (N-2-fluorenylacetamide), it was demonstrated that the cytoplasmic DNA polymerase-alpha (E.C. 2.7.7.7) was strikingly error-prone when compared to that of normal liver (Chan, J.Y.H. and Becker, F.F. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 814-818). The fidelity of polymerization of these enzymes was assayed by determining the incorporation of noncomplementary deoxyribonucleotide triphosphates (misincorporation) on a poly(dA-dT) template. To identify the mechanism of infidelity, we modified and extended our purificaton scheme. As a result, a subspecies of polymerase-alpha 1 was identified and separated from the normal component, polymerase-alpha 2. Polymerase-alpha 1 activity eluted from a phosphocellulose column at 0.07-0.12 M NaCl, while polymerase-alpha 2 eluted at 0.15-0.2 M NaCl. Polymerase-alpha 2 demonstrated normal fidelity throughout the various steps of purification while polymerase-alpha 1, despite being purified some 10 250-fold, continued to demonstrate a severe degree of infidelity.

Covalent binding of 2-acetylaminofluorene, 2-aminofluorene, and N-hydroxy-2-acetylaminofluorene to rat liver nuclear DNA and protein in vivo and in vitro

Binding of the hepatocarcinogen 2-acetylaminofluorene (AAF) and two metabolites, 2-aminofluorene (AF) and N-hydroxy-2-acetylaminofluorene (N-OH-AAF), to the DNA and protein of rat hepatic nuclei was examined in vitro and in a cell-free system. Three and one-half hr following a single injection of each compound in equimolar amounts. DNA contained approximately 50% more of the compounds per mg than did protein. The amount of N-OH-AAF bound to DNA was 4 times greater than that of AAF, while AF bound in intermediate amounts. When incubated with nuclei in a cell-free system, AAF seldom bound in measurable amounts, while significant amounts of N-OH-AAF and AF bound to both DNA and protein. As occurred in vivo, DNA bound more of each per mg than did protein. The amount of N-OH-AFF bound to intranuclear DNA increased 54% when an aliquot of the postmicrosomal liver fraction was added to the incubation mixture, but maximum binding of AF occurred in the absence of any other liver fraction. Thus, it was shown that two AAF metabolites, AF and N-OH-AAF, bind covalently to the DNA and protein of hepatic nuclei more readily than does AAF itself and that binding in a cell-free system parallels binding in vivo. Additional evidence suggests that rat hepatic nuclei are capable of mediating the binding of AF and N-OH-AAF to macromolecules through distinct enzyme systems. This is the first demonstration that the nucleus is capable of metabolizing AF to an electrophile that can bind covalently to DNA.

Diminished hepatic binding protein for desialylated glycoproteins during chemical hepatocarcinogenesis

The lectin hepatic binding protein has a specific binding capacity for desialylated serum glycoproteins and is limited to hepatocyte membranes. This binding capacity was reduced by approximately 60% in the neoplastic nodules which resulted from exposure of rat livers to N-2-acetylaminofluorene. The binding capacity of the primary hepatocellular carcinomas which resulted from this regimen was reduced by 95%. The loss of binding capacity was found to be proportional to the decreased concentration of immunologically detectable lectin in the altered tissues.

EcoRI-generated reiterated components of the rat genome. I. Sequence of two (92 and 93 bp) related DNA fragments

The sequence of the 92 and 93 bp long, highly repetitive DNA fragments, isolated from EcoRI digested rat liver DNA, were determined. These fragments, designated 92 and 93, are found in equal abundance, 6.5 x 10(5) copies per haploid genome. J92 and J93 can be distinguished by their differential sensitivity to cleavage by HaeIII and HindIII, respectively, which cut the fragments at 75 and 57 bp from their mutually homologous 5'-ends. J92 and J93 are 38% and 35.4% G + C, respectively, and contain a disproportionate number of triplets complementary to stop codons in all reading frames. Three methylated sites were found in J92 while none could be detected in J93. The sequences around the m5C sites were 5'-Py-Py-m5C-G-Pu-Pu, except for one case where the second Py was replaced by an A. This site appeared to be hemimethylated. When J92 and J93 are placed in register from their mutually homologous 5'-ends, homology is 73% for the first 30 bp region and 63.5% for the total molecule. Thermal melting studies indicate sequence heterogeneity within J92 and J93 from substantial internal base mismatches. The sequences derived are therefore composite averages for the whole molecules. The Cot1/2 for the sequence was measured spectrophotometrically to be 2 x 10(-2) M/s on a DNA phosphorus basis and 2.15 x 10(-4) M/s on a mole fragment basis.

Progressive DNA damage in hepatic nodules during 2-acetylaminofluorene carcinogenesis

The method of alkaline elution was used to detect DNA alteration in rat liver throughout the carcinogenic sequence that resulted from exposure to a standard four-cycle feeding regimen of 2-acetylaminofluorene (AFF). At the end of 3 weeks of AAF feeding, DNA from aliquots of whole liver demonstrated a small but significant degree of damage. By the end of the fourth AAF feeding, the liver exhibited numerous nodules that could be dissected free from surrounding tissue. DNA from these putative premalignant lesions showed approximately 136% more damage than that seen at the end of 3 weeks of AAF feeding. Two to 4 months following the cessation of AAF, DNA from persistent nodules was examined for eivdence of alteration. Despite the prolonged absence of exposure to AAF, DNA damage was found to have progressed and was as much as 320% greater than that seen at the end of the first cycle. While the persistence of DNA damage during chronic exposure to a carcinogen has been reported previously, the observations that the DNA of a focal lesion which is putatively premalignant was damaged and, further, that this alteration progressed in the absence of a carcinogen, are unique.

Analysis of highly repeated DNA sequences of rat with EcoR1 endonuclease

Cleavage of rat liver nuclear DNA with EcolR1 restriction endonuclease yields 14 discrete fragments ranging from 2300 to 93 base pairs in length, representing approx. 10.5% of the rat genome. Fragments of 1500, 180, and 93 base pairs are reiterated over 100 000 times; fragments of 2300, 880, 290, and 200 base pairs are reiterated over 20 000 times; the remaining fragments are present in over 1000 copies per genome. When compared to whole rate DNA, 11 were 1-5% richer in A . T base pairs and five were 1.5-2.5 times more methylated. From the criteria of the banding patterns in complete and incomplete digests, base composition and extent of methylation, none of these fragments appeared to be generated as oligomers of a basic shorter repeat. The reassociation of EcoR1 fragments was monitored on hydroxyapatite and by S1 nuclease treatment in order to assess band reiteration frequency and the possibility of interpersion or short internal repeats. The renaturation of the four smallest EcoR1 fragments gave no indication of short internal repeats from hyperpolymer formation nor interpersion with lower frequency sequences by size reduction after S1 nuclease treatment. Anomalous renaturation of several large fragments was observed, possibly due to internal repeats.

Purification of a low molecular weight non-histone chromosomal protein

A non-histone chromosomal proteins was extracted from rat liver chromatin with 0.35 M NaCl and purified more than 2758 times to near homogeneity by hydroxyapatite, gel filtration, and phosphocellulose chromatography. The final fraction was greater than 95% pure as judged by non-denaturing gel electrophoresis. The protein, designated loosely bound non-histone chromosomal protein 1, had an observed molecular weight of 15 700. This protein was demonstrated to increase the amount of RNA synthesized in a heterologous (Escherichia coli RNA polymerase) transcription system and, therefore, this activity was also used to monitor its purification. The availability of highly purified loosely bound non-histone chromosomal protein 1 will make possible an examination of its structural and/or functional role in chromatin.

Alterations in chromosomal proteins in C3H/HeN mice with spontaneous primary hepatocellular carcinomas

The chromosomal proteins from chromatins of normal and background liver and spontaneous primary hepatocellular carcinomas (PHC) of C3H/HeN mice were examined by high resolution acid-urea and sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. Before gel analysis, the histone and non-histone chromosomal proteins (NHCP) from the various tissues studied were separated by affinity chromatography. No qualitative or quantitative differences in histone content were detected in any of the chromatins studied. Tumor and background chromatins did, however, exhibit higher NHCP content than normal tissues. When NHCP were fractionated on SDS polyacrylamide gels, the appearance of 10 new unique NHCP, many of which were of high molecular weight, was found to accompany the manifestation of malignancy in these C3H/HeN mice. Conversely, the abundance of a number of individual NHCP decreased precipitiously in PHC chromatin; and, additionally, two high-molecular-weight NHCP present in normal chromatins were not detectable in background and PHC chromatin. A number of NHCP were found to be unique to each of the chromatins studied. The progressive increase in total number of NHCP in background and PHC chromatin when compared to normal chromatin suggested that such changes in NHCP might indicate progression towards malignancy. The acquisition of new high-molecular-weight NHCP, the loss of some high-molecular-weight NHCP, and the decrease in individual NHCP found for mouse PHC correlate well with findings of previous studies in other systems in which malignant transformation was induced with some agent. It appears then that changes in NHCP accompany both spontaneous and induced malignant transformation, and that such changes may reflect alterations in gene expression known to accompany malignancy.

Lack of proportionality between rate of cell division and induction of tumors in carcinogen-exposed regenerating livers

Although a single pulse of dimethylnitrosamine administered during the regenerative response of liver subsequent to 70% hepatectomy resulted in more primary hepatocellular carcinomas in treated livers than in controls, the response was not proportionate to the level of cell division. Further, the use of 55-g male Sprague-Dawley rats that displayed an extremely active regenerative response did not significantly shorten the lag period before the appearance of tumors. Of additional interest was the finding that the post-S period might be even more susceptible to dimethylnitrosamine than the S phase was. These results support the suggestion that many aspects of the interaction between carcinogens and dividing cells and the requirement for subsequent events for the development remain unclear.

Analysis of chromosomal proteins of fractionated chromatin from rat liver and transplantable hepatocellular carcinomas

The chromosomal proteins from a number of transplantable hepatocellular carcinomas (THC) induced by a single carcinogen or its derivatives and varying greatly in their growth rates were examined by sodium dodecyl sulfate (SDS) polyarcylamide gel electrophoresis. Before extraction and analysis of proteins, chromatin from hepatomas, as well as from normal and regenerating liver was fractionated into rapidly and slowly sedimenting gradient components. Ten non-histone chromosomal proteins (NHCP) present in the tumors and ranging in molecular weight from 220,000 to 55,000, were absent from normal liver. Further, each rapidly growing tumor possessed more non-histone protein bands in the most rapidly sedimenting chromatin fractions than did corresponding, slowly growing tumor fractions. A number of single protein occurrences common only to normal liver and/or rapidly or slowly growing tumors were also found. In contrast, NHCP banding patterns of rapidly growing 70% hepatectomized rat liver were identical to those of non-dividing liver. Of particular interest was the finding that the prototypic "minimal deviation tumor" 9618A varied more in its NHCP-banding pattern when compared to liver than did those tumors which were rapidly growing and poorly differentiated. These studies represent an initial attempt at seeking NHCP which might be uniquely related to the malignant process.

Immunocytochemical localization of epoxide hydrase in hyperplastic nodules induced in rat liver by 2-acetylaminofluorene

A knowledge of the biological characteristics of carcinogen-induced hyperplastic nodules of rat liver may be important in the understanding of cancer development. Although its biological role remains to be elucidated, the level of microsomal epoxide hydrase (epoxide hydrolase, EC 3.3.2.3) is 5- to 7-fold greater in hyperplastic nodules nodules induced by feeding the hepatocarcinogen 2-acetylaminofluorene than in liver of control rats. After removal of the carcinogen from the diet, the high level of the enzyme is maintained in those nodules that persist and in the hepatocellular carcinomas that subsequently develop. The availability of antibody to the epoxide hydrase made it possible to use electron microscopic immunocytochemistry to localize this enzyme in the cells of hyperplastic nodules. The immunocytochemical procedure provides direct visual evidence for the presence of this enzyme in smooth endoplasmic reticulum and also in rough endoplasmic reticulum (including the nuclear envelope) of the nodule's parenchymal cells.

In vivo binding of N-2-acetylaminofluorene and its N-hydroxy derivative to the DNA of fractionated rat liver chromatin

The in vivo binding of radioactive N-2-acetylaminofluorene (AAF) and N-hydroxy-2-acetylaminofluorene (N-OH-AAF) to the DNA of rat liver chromatin was examined. The chromatin was fractionated into putative transcriptionally active and inactive fractions by hydrodynamic shearing and subsequent glycerol gradient centrifugation, DNAase II digestion followed by MgCl2 aggregation of transcriptionally inactive chromatin, or mild digestion with micrococcal nuclease. Carcinogens were administered for various times prior to sacrifice. Irrespective of the duration of exposure, no preferential binding of either carcinogen to DNA was detected in any of the fractions prepared by hydrodynamic shearing of DNAase II digestion. When micrococcal nuclease was utilized, a 2-fold increase in carcinogen bound to the DNA of that chromatin fraction containing the smallest molecular weight fragments was detected. These small molecular weight fragments produced by micrococcal nuclease have been postulated to be derived from in vivo transcriptional units. Additionally, when DNAase II was used to probe chromatin from rat livers which had been exposed to a carcinogenic regimen of AAF, no preferential binding of radioactive N-OH-AAF to the DNA of any chromatin fraction was detected.

Rhomboid flap in facial reconstruction. New concept of tension lines

The rhomboid flap has become a popular reconstructive alternative for facial defects in recent years. Since the original description by Limberg, several modifications of the flap have been described, the most important of which was by Dufourmental. In the literature and at many soft-tissue courses, it has been taught that after rotation the maximum tension of the rhomboid flap is at the corner of the rhomboid most distant from the transposed flap. The author shows that the maximum tension of the flap is at the closure of the donor area. This phenomenon is amply illustrated with clinical cases. The Dufourmental modification is more satisfactory than the classical rhomboid flap in most cases because there is less tension on the closure. An understanding of these concepts is essential to the successful use of this important flap in order to avoid distortion of vital facial landmarks. I report a series of 30 consecutive rhomboid flaps.

Rat alpha-macrofetoprotein (acute-phase alpha 2-macroglobulin) during hepatocarcinogenesis

Rat alpha-macrofetoprotein (AMF) and alpha-fetoprotein (AFP) are secreted by the fetal liver and become elevated in serum during hepatocarcinogenesis and in animals bearing hepatocellular carcinomas. It has been suggested that these fetal plasma proteins may be influenced by related control mechanisms. The experiments presented herein examined the early responses of these plasma proteins during hepatocarcinogenesis using the hepatocarcinogens acetylaminofluorene and diethylnitrosamine. Under these conditions, AFP serum concentrations were elevated within a few days of exposure to acetylaminofluorene, whereas AMF serum concentrations remained essentially normal. AFP became elevated after a number of weeks of exposure to diethylnitrosamine. In either regimen, AMF became elevated only later when large primary hepatocellular carcinomas were found. The time of appearance of AMF after transfer of an AFP-secreting Morris hepatoma indicated that AMF was elevated only in animals with extremely large, necrotic tumors. Thus, it appears that elevation of serum AFP resulted from either exposure to hepatocarcinogens or production by hepatocellular carcinomas, but that the elevations of serum AMF levels resulted from inflammatory injury or necrosis of tumor tissues.

alpha-Fetoprotein levels and hepatic alterations during chemical carcinogenesis in C57BL/6N mice

Hepatocellular carcinomas were induced by administration of acetylaminofluorene or chlordane to C57BL/6N mice. Lesions which closely resembled the neoplastic nodule described as a putative premalignant lesion in rats were evident. alpha-Fetoprotein elevations were noted only in the presence of the malignant lesions for both carcinogens. In this regard, the responses of these mice were similar to those seen during spontaneous hepatocarcinogenesis.

Decreased fidelity of DNA polymerase activity during N-2-fluorenylacetamide hepatocarcinogenesis

alpha and beta DNA polymerases (DNA nucleotidyltransferase; deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) were isolated from nuclear and cytoplasmic fractions of rat livers exposed to a carcinogenic regimen with the hepatocarcinogen N-2-fluorenylacetamide and from 24-hr regenerating liver. The fidelity of polymerization of these enzymes was compared by determining the incorporation of noncomplementary deoxyribonucleoside triphosphates (misincorporation) on a poly(dA-dT).poly(dA-dT) template, with MnCl2 and MgCl2 as divalent cations. Our initial studies indicate that the cytoplasmic alpha polymerases from carcinogen-exposed rat livers were strikingly error-prone whereas the nuclear and cytoplasmic beta polymerases retained their fidelity throughout the feeding cycles. The misincorporation was significantly accentuated by MnCl2 compared with that obtained with MgCl2 as divalent cation. The products were sensitive to pancreatic DNase I digestion, indicating that the noncomplementary bases had been incorporated by the polymerization process. Nuclear alpha polymerase showed some degree of infidelity but less than that of cytoplasmic alpha polymerase.

Comparison of transcription stimulating, phenol-soluble non-histone chromosomal proteins in normal rat liver and transplantable hepatocellular carcinomas

The non-histone chromosomal proteins (NHCP) of a rapidly and slowly proliferating transplantable hepatocellular carcinoma (THC) were compared to those of normal and regenerating rat liver. The total quantity of NHCP is approximately threefold higher in the THCs than in either normal rat liver at 4 h and 44 h regenerating rat liver. Only those NHCP that can be extracted from chromatin by 0.35 M NaCl were further examined and it was observed that the proteins of this highly complex fraction could be further fractionated by their differential phenol-solubility. The phenol-soluble 0.35 NHCP contained protein(s) capable of stimulating the level of DNA-directed RNA synthesis in vitro. The total amount of this stimulatory activity was 5 times higher in the rapidly growing THC and 1.6 times higher in the slowly growing THC than in normal rat liver. In order to assess the contribution of cell-cycle dependent alterations on the increase in the amount of stimulatory activity in the THCs, 44 h regenerating rat livers were examined. This tissue represents a mix of cells in various stages of the cell cycle which is similar to that found in the THCs. It was found that the total quantity of NHCP in the 44 h regenerating rat liver was the same as in normal rat liver. The total amount of the stimulatory activity also was similar in both the normal and 44 h regenerating rat liver. The amount of the stimulatory activity was found to double in 4 h regenerating rat liver, however. These data suggest that the alterations observed in the NHCP of the THCs are not due solely to cell cycle dependent changes, but may represent malignancy dependent alterations.

Activation of endogenous type-C viral p30 antigen in chemically-induced rat hepatocellular carcinomas

Chemically induced rat hepatocellular carcinomas were prospectively examined for expression of the major group-specific antigen (p 30) of genetically transmitted rat type-C viruses. Ten primary tumors induced following oral administration of the carcinogen N-2-acetylaminofluorine did not express elevated levels of viral antigen as compared to antigen levels detected in normal liver tissue. By contrast, rapidly growing transplantable hepatocellular carcinomas (THCs) derived from primary tumor expressed increased quantities of viral antigen. The expression of antigen was marginally elevated after only one transplanation, increased to maximal levels after several transplant generations and, once achieved, was stably maintained throughout subsequent transplants. Studies with additional previously established THCs showed that poorly differentiated, rapidly proliferating tumors tended to express elevated levels of viral antigen, while more differentiated, slowly growing tumors did not. The results show that the expression of endogenous type-C viral 30 antigen is a stable phenotypic property of many rat THC lines.

Lentigo maligna and lentigo maligna melanoma. Recognition and treatment

Lentigo maligna is the preinvasive stage of lentigo maligna melanom, which is a specific type of cutaneous malignant melanom found almost exclusively in the head and neck area. The distinguishing features and the biological behavior of this disease are discussed. Emphasis is placed on early diagnosis by clinical differentiation from other pigmented lesions and by biopsy specimen. Treatment by adequate surgical removal with appropriate reconstruction is discussed and illustrated with case reports.

Patterns of spontaneous metastasis of transplantable hepatocellular carcinomas

A number of transplantable rat hepatocellular carcinomas of varied phenotype were examined for their ability to metastasize. A striking diversity of pattern was observed, ranging from presentation in almost every organ to none at all. No relationship between metastatic capability and growth rate, tumor size, chromosome composition, or other functional characteristics was noted. Interestingly, several of the tumors demonstrated a lymphatic to vascular route of spread, very similar to that of human tumors.

Reconstruction of facial defects resulting from Mohs' chemosurgical procedures

A philosophy of reconstruction after removal of cutaneous neoplasms from the face is presented and differences in reconstruction required after Mohs' fixed-tissue and fresh-tissue techniques are discussed. The indications for repair at once or later of facial defects after Mohs' procedures are reviewed and reconstructive alternatives are presented. Illustrative case reports of such cases that have been reconstructed are recounted and commented on. It is likely that the practice of the fresh-tissue technique will stimulate more interest in reconstructing facial defects resulting from that type of operation immediately, or at least sooner than later.

Chromosome analysis of hepatocellular carcinoma 7777 and correlation with alpha-fetoprotein production

The Morris hepatocellular carcinoma 7777 is productive of extraordinarily high levels of the oncofetal protein, alpha-fetoprotein. Its chromosome composition was examined in detail since it represents the only near-diploid tumor of such productivity and has been reported to demonstrate a single unusual chromosomal alteration. The major finding is the presence of a submetacentric marker chromosome, composed of a No. 7 chromosome and a short arm that demonstrated a poorly defined banding pattern on Giemsa staining. This marker is unique to 7777 and is of particular interest in view of recent reports of an association between such unbanded chromosome arms and supraproduction of cell products.

Endogenous DNA polymerase activity in fractionated rat lever chromatin

Chromatin isolated from adult rat liver was fractionated into template active and inactive components by controlled shearing and glycerol gradient centrifugation. The fractionated chromatin was assayed for DNA-dependent DNA polymerase (DNA mucleotidyl transferase EC 2.7.7.7) activity with and without exogenous activated DNA serving as template. With endogenous chromatin as template, it was found that 90% of the endogenous chromatin bound DNA polymerase activity was located in the transcriptionally active fraction of chromatin, while the distribution of DNA polymerase assayed with exogenous activated DNA was found to be 65% in the transcriptionally active and 35% in the inactive fractions. However, when DNA polymerase was solubilized from these fractions by salt extraction, enzyme activity was found to be equally distributed, suggesting that the difference in endogenous DNA polymerase activity observed between eu- and heterochromatin is due to the restricted template found in repressed fractions.

Normal endonuclease activities for damaged DNA during hepatocarcinogenesis

Two endonuclease activities in rat liver for damaged DNA were assayed. Double-stranded, covalently closed DNA from phage PM2 was damaged by either ultraviolet irradiation or by heating at acid pH, and used as substrate for endonucleases specific for ultraviolet DNA damage and for DNA apurinic sites, respectively. The levels of both enzyme activities in livers of normal rats were compared to levels in livers of rats fed N-2-acetylaminofluorene. At critical stages of the carcinogenic regimen levels of both endonuclease activities were normal. This, together with other data, suggests that depression of excision-repair of DNA damage does not take place during experimental carcinogenesis.

Local tissue flaps in reconstructive facial plastic surgery

When a lesion is excised from the facial are and the defect cannot feasibly be closed primarily or by secondary healing, skin grafting or adjacent tissue transfer is usually used to close the defect. In the facial area, adjacent tissue transfer gives a better color and texture match and is preferred over skin grafting whenever possible. This paper presents some local flaps which are available for reconstruction of surgical defects in the facial area.

Serum alpha-fetoprotein in a mouse strain (C3H-Avy fB) with spontaneous hepatocellular carcinomas

In a study of the association between circulating alpha-fetoprotein concentrations and spontaneous hepatocellular carcinomas, we examined C3H-Avy fB mice, which with age consistently demonstrate a rapidly increasing incidence of hepatic cancer. Although elevated alpha-fetoprotein levels are observed in association with the majority of these tumors, no elevation of alpha-fetoprotein was observed during the life course of non-tumor-bearing mice despite their age-dependent risk for hepatic cancer. Therefore, whatever the evolutionary or age-related biological changes may be that lead to tumor formation in this mouse, they are not linked to the synthesis of significant amounts of this oncofetal protein.

Expression of an oncodevelopmental gene product (alpha-fetoprotein) during fetal development and adult oncogenesis

The expression of an "oncodevelopmental" protein, alpha-fetoprotein (AFP), has been systematically studied in rats during normal development and during regeneration of the liver by fetal rat hepatocytes in vitro, in rats bearing transplantable hepatomas, in rats fed chemical carcinogens, and in mice that spontaneously develop hematomas. AFP is a serum protein made normally during fetal and neonatal stages by liver and yolk sac cells. In newborn rats at approximately 4 weeks of age, the production of AFP is abruptly terminated, a process which is closely associated with cessation of liver cell proliferation. In adult rats, AFP production recurs following the reinitiation of hepatic DNA synthesis induced by partial hepatectomy or by the administration of heaptotoxic chemicals. Detailed metabolic and direct labeling studies of fetal rat hepatocytes in vitro also demonstrate a kinetically similar pattern of hepatocyte DNA synthesis and AFP production. In vitro studies utilizing combined autoradiography for DNA-synthesizing cells and immunofluorescence for AFP-containing cells demonstrates that replicating hepatocytes produce AFP, however, available data do not yet permit a distinction between G1 (pre- or postmitotic) and/or G2 production. During growth of an AFP- producing tumor, the serum concentration of AFP may be used as a accurate index of tumor growth, and, if a transplanted tumor is removed, as a marker for metastatic growth of the tumor. Using this model, we have shown that radiation to the lung at the time of surgical removal of a growing tumor in the leg will prevent establishment and growth of pulmonary metastases and that anti-AFP serum treatment may inhibit growth of a transplantable hepatoma that produces AFP. The exposure of rats to chemical hepatocarcinogens results in the appearance of evaluated serum AFP concentration as early as within 1 week of feeding; noncarcinogenic chemical analogs do not cause an elevation. AFP elevation also occurs with low doses of the hepatocarcinogen in the absence of detectable cell injury (by morphological examination of serum enzyme levels) or any other known morphological or biochemical change. This may represent a highly selective derepression of protein synthesis that occurs following the formation of a complex between the metabolites of the carcinogen and specific chromatin loci. Although every rat so far treated with even subcarcinogenic doses of hepatocarcinogens has elevated serum AFP concentrations, many primary carcinogen-induced hepatomas do not produce detectable AFP. Either there is a subsequent change in the preneoplastic AFP-producing cell that occurs prior to irreversible neoplastic alteration, or the hepatocytes originally influenced by the carcinogens to produce AFP are not necessarily the same cells that are the progenitors of the hepatoma produced by more prolonged exposure...