Parathyroid hormone-related protein gene expression in human squamous carcinoma cells is repressed by mutant isoforms of p53

Parathyroid hormone-related protein (PTHrP) is a normal secretory product of a variety of squamous epithelia, including epidermal keratinocytes. Only a subset of squamous carcinomas, however, express the gene at levels sufficient to cause humoral hypercalcemia. In the present study, comparison of PTHrP expression levels with p53 functional status in a series of squamous carcinoma lines has revealed an association between expression of specific mutant isoforms of p53 and very low levels of PTHrP mRNA. Evaluation of p53 isoforms with mutations in codons 248 and 273 showed them to be capable of repressing PTHrP gene expression in a high-expressing, p53-negative squamous line by approximately 50%. Conversely, inactivation of an endogenous mutant p53 with E1B proteins resulted in an increase in PTHrP expression in a low-expressing cell line. Subsequent analysis of promoter-specific PTHrP transcripts in a p53-negative squamous line transfected with mutant p53 isoforms suggested that down-regulation occurred primarily at the two TATA-based promoters. Direct testing of a murine PTHrP reporter construct in transient transfection assays confirmed the capacity of the 248 and 273 mutants to repress this TATA-based promoter, although only about half as effectively as wild-type p53.

Transactivation of the PTHrP gene in squamous carcinomas predicts the occurrence of hypercalcemia in athymic mice

Humoral hypercalcemia of malignancy (HHM) is caused by the secretion of parathyroid hormone-related protein (PTHrP) by tumor cells, and tumors of squamous histology are the ones most commonly complicated by HHM. To determine why some squamous tumors cause HHM and others do not, we quantitated the levels of PTHrP mRNA expression and PTHrP secretion in a series of eight squamous tumor lines. As anticipated, we found that the level of PTHrP mRNA expression in individual lines correlated with their PTHrP secretion rates. However, PTHrP mRNA levels varied widely in individual lines, and only those tumor lines with the highest levels of PTHrP gene expression were able to cause hypercalcemia in athymic mice. We found that a specific segment of the PTHrP promoter could reproduce the relative pattern of PTHrP gene expression when cloned in front of a chloramphenicol acetyltransferase reporter gene and transiently transfected into these squamous lines. Deletional analysis confirmed that specific sequences within the PTHrP gene promoter appeared to be involved in the transactivation of the gene in tumor lines expressing high levels of PTHrP mRNA. These data suggest that the ability of a given squamous tumor to cause HHM is ultimately a function of its level of PTHrP gene expression, which in turn appears to be a function of the ability of specific transcription factors to transactivate PTHrP gene expression.

Adolescents' misinterpretation of health risk probability expressions

OBJECTIVE

To determine if differences exist between adolescents and physicians in their numerical translation of 13 commonly used probability expressions (eg, possibly, might).

DESIGN

Cross-sectional.

SETTING

Adolescent medicine and pediatric orthopedic outpatient units.

PARTICIPANTS

150 adolescents and 51 pediatricians, pediatric orthopedic surgeons, and nurses.

MEASUREMENT

Numerical ratings of the degree of certainty implied by 13 probability expressions (eg, possibly, probably).

RESULTS

Adolescents were significantly more likely than physicians to display comprehension errors, reversing or equating the meaning of terms such as probably/possibly and likely/possibly. Numerical expressions of uncertainty (eg, 30% chance) elicited less variability in ratings than lexical expressions of uncertainty (eg, possibly).

CONCLUSION

Physicians should avoid using probability expressions such as probably, possibly, and likely when communicating health risks to children and adolescents. Numerical expressions of uncertainty may be more effective for conveying the likelihood of an illness than lexical expressions of uncertainty (eg, probably).

Birth-weight ratio and cerebral palsy

The birth-weight ratio, a convenient measure of fetal growth, has been used to assess the importance of antecedent and perinatal factors in a retrospective analysis of 605 cases of congenital cerebral palsy. All had been seen by the author at a special clinic over a period of three decades. The ratio (normally 1) is high in the very premature, falls in the middle of the third trimester, then begins to rise again at term. Abnormalities of pregnancy, or a history of maternal pregnancy-losses, depress the ratio perceptibly. In both singletons and twins, there is no significant relationship between a low ratio and the severity of the clinical condition, and presumably the extent of the brain damage. The findings suggest that growth retardation is an association and not a cause of perinatal vascular-anoxic lesions.

Physicochemical and immunological characterization of the type E botulinum neurotoxin binding protein purified from Clostridium botulinum

Type E botulinum neurotoxin is produced by Clostridium botulinum along with a neurotoxin binding protein which helps protect the neurotoxin from adverse pH, temperature, and proteolytic conditions. The neurotoxin binding protein has been purified as a 118-kDa protein. Secondary structure content of the neurotoxin binding protein as revealed by far-UV circular dichroism spectroscopy was 19% alpha-helix, 50% beta-sheets, 28% random coils, and 3% beta-turns. This compared to 22% alpha-helix, 44% beta-sheets, 34% random coils, and no beta-turns of the type E botulinum neurotoxin. The complex of the two proteins revealed 25% alpha-helix, 45% beta-sheets, 27% random coils, and 3% beta-turns, suggesting a significant alteration at least in the alpha-helical folding of the two proteins upon their interaction. Tyrosine topography is altered considerably (28%) when the neurotoxin and its binding protein are separated, indicating strong interaction between the two proteins. Gel filtration results suggested that type E neurotoxin binding protein clearly complexes with type E neurotoxin. The interaction is favored at low pH as indicated by an initial binding rate of 8.4 min-1 at pH 5.7 compared to 4.0 min-1 at pH 7.5 as determined using a fiber optic-based biosensor. The neurotoxin and its binding protein apparently are of equivalent antigenicity, as both reacted equally on enzyme-linked immunosorbent assay to polyclonal antibodies raised against the toxoid of their complex.

Expression of the neural intermediate filament proteins peripherin and neurofilament-66/alpha-internexin in neuroblastoma

BACKGROUND

Peripherin and neurofilament (NF)-66/alpha-internexin are recently characterized, neuron-specific intermediate filament proteins that are expressed in the developing peripheral nervous system. Peripherin, in particular, is highly enriched in neuronal derivatives of the neural crest. We speculated that these intermediate filament proteins would be expressed in neuroblastoma (NB), a neural crest-derived tumor with many neuronal features.

EXPERIMENTAL DESIGN

By use of antibodies specific to peripherin and NF-66/alpha-internexin, we detected these proteins on Western blots of NB tissue extracts and in paraffin sections of NBs.

RESULTS

Western blotting indicated that NB tumor extracts contained immunoreactive proteins that co-migrated with rat peripherin and human NF-66/alpha-internexin from normal tissues, thus establishing the specificity of the antibodies for these proteins in tumors. The antibody specific for peripherin labeled all NBs, including immature NBs, composite ganglioneuroblastomas and ganglioneuromas. In contrast, the NF-66/alpha-internexin antibody labeled only 50% of NBs, and only weakly labeled most ganglioneuroblastomas and ganglioneuromas. Neither antibody labeled other small blue cell tumors such as lymphomas, rhabdomyosarcomas, Wilms' tumors, and Ewing sarcomas.

CONCLUSIONS

The specificity of the peripherin labeling of NB and the ability of the peripherin antibody to label the entire spectrum of NBs, including ganglioneuroblastomas and ganglioneuromas, indicate that this intermediate filament protein has potential as a diagnostic marker for these related neural crest neoplasms.

The structure of the human peripherin gene (PRPH) and identification of potential regulatory elements

We determined the complete nucleotide sequence of the coding region of the human peripherin gene (PRPH), as well as 742 bp 5' to the cap site and 584 bp 3' to the stop codon, and compared its structure and sequence to the rat and mouse genes. The overall structure of 9 exons separated by 8 introns is conserved among these three mammalian species. The nucleotide sequences of the human peripherin gene exons were 90% identical to the rat gene sequences, and the predicted human peripherin protein differed from rat peripherin at only 18 of 475 amino acid residues. Comparison of the 5' flanking regions of the human peripherin gene and rodent genes revealed extensive areas of high homology. Additional conserved segments were found in introns 1 and 2. Within the 5' region, potential regulatory sequences, including a nerve growth factor negative regulatory element, a Hox protein binding site, and a heat shock element, were identified in all peripherin genes. The positional conservation of each element suggests that they may be important in the tissue-specific, developmental-specific, and injury-specific expression of the peripherin gene.

Ras mutations in methylclofenapate-induced B6C3F1 and C57BL/10J mouse liver tumours

The majority of genotoxic carcinogen-induced liver tumours of the sensitive B6C3F1 mouse contain activated H-ras oncogenes. Such mutations also occur in hepatocarcinogenesis-resistant strains. In order to determine whether this is true of non-genotoxic carcinogen-induced tumours, liver tumours induced in B6C3F1 and C57BL/10J mice by methylclofenapate (MCP) were compared. Polymerase chain reaction (PCR) analysis revealed H-ras codon 61 mutations in 11/46 B6C3F1 and 4/31 C57BL/10J liver tumours. The nude mouse tumorigenicity (NMT) assay was used to analyse tumours without codon 61 mutations. Of the 12 B6C3F1 liver tumour DNAs subjected to this assay, one contained a H-ras codon 117 mutation. Further PCR analysis on frozen tumour samples (46 B6C3F1 and 15 C57BL/10J) revealed no codon 12 mutations; one additional codon 117 mutation was identified in a B6C3F1 tumour. Overall, then, H-ras codon 61 mutations were detected in MCP-induced B6C3F1 tumours less frequently than in genotoxin-induced tumours. Two B6C3F1 tumours contained codon 117 mutations similar to those previously found in tumours induced by ciprofibrate, furan and furfural, and in at least one spontaneous tumour. Ras mutations were also detected in some C57BL/10J tumours, providing further evidence that ras oncogenes can participate in hepatocarcinogenesis in resistant mice.

Comparison of proliferating cell nuclear antigen to tritiated thymidine as a marker of proliferating hepatocytes in rats

Proliferating cell nuclear antigen (PCNA), an endogenous nuclear protein, has recently been used to identify replicating cells. PCNA was compared to tritiated thymidine ([3H]-TdR), a reliable and accurate exogenous labeling agent, to ascertain if PCNA gives comparable results for quantitative cell proliferation. Male F344 rats were treated with a single dose of 500 mg/kg 4-acetylaminofluorene (4-AAF), a known liver mitogen. Rats (n = 5) were euthanized and necropsied at 6, 12, 18, 24, 36, 48, 96, or 192 hr after treatment. Two hours before necropsy, rats were pulsed-dosed with [3H]-TdR (2 mCi/kg body weight). Livers were sectioned, autoradiography performed, and labeling indexes (LI), a measurement of the percentage of S-phase hepatocytes, determined. One and a half years after the completion of this study, the archival paraffin blocks of the liver tissue were sectioned and stained for PCNA by an immunohistochemical procedure. Immunocytochemical staining patterns of proliferating cell nuclear antigen antigen expression permitted the recognition of G1, S, G2, M, and quiescent cells. PCNA LI, generated by scoring only cells exhibiting S-phase staining patterns, was compared to the pulse [3H]-TdR LI for each animal. Similar periportal staining patterns of S-phase nuclei were detected by both markers. The [3H]-TdR LI and the PCNA LI exhibited a peak at 24 hr of approximately the same magnitude. However, while the [3H]-TdR LI had returned to near baseline at the 48-hr time point, the PCNA LI remained elevated until the 96-hr time point. This sustained elevation of the PCNA index cannot be explained at this time.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of the health care sector in the U.S. economy

This Issue Brief discusses factors that contribute to the growth of health care expenditures and the reasons that many individuals, employers, and policymakers consider health expenditures too high. In addition, it describes various industries that make up the health care delivery system and their role in the U.S. economy as employers, producers, exporters, and suppliers of research and development. The report also discusses the economic implications of rising health care expenditures for individuals, employers, and the federal government and the potential impact of proposed health care reform on the health care sector and the U.S. economy as a whole. Health care delivery industries such as pharmaceuticals and medical equipment suppliers have higher than average research and development levels, in addition to a positive balance of trade. Moreover, while the total number of jobs in the private sector declined between 1990 and 1993, the number of jobs in the relatively high paid health services sector continued to grow. In aggregate, employer spending on health care represents only 6.6 percent of total labor costs. In comparison, wages and salaries represent 83 percent of total labor costs. Consequently, the growth rate of health care expenditures has a smaller impact on the growth rate of total compensation than does the growth rate in wages and salaries. Using job multipliers developed by the U.S. Department of Commerce, it is estimated that the 18,600 health care services jobs in Rochester, Minnesota in 1993 created another 32,000 jobs in the area. Any contraction of the health care sector in cities that have a large concentration of employment in health services would result in reduced employment in restaurants, retail stores, janitorial services, and other local businesses. EBRI's simulations estimated that between 200,000 and 1.2 million workers could become unemployed as a direct result of a mandate that employers provide health benefits to their employees, assuming that wages and salaries did not adjust at all. Others find that approximately 50,000 individuals would lost their jobs, assuming that wages and other labor costs adjust downward to completely account for increased costs. As is apparent, the estimates of job loss (and of the total costs of the policy) are extremely sensitive to the assumptions used in the simulation.

Flexible benefits, choice, and work force diversity

This Issue Brief evaluates the prevalence of flexible benefits plans and their ability to achieve cost management goals and to meet the needs of diverse employee groups. In addition, it examines flexible benefits plans' current legislative and regulatory status and typical plan design features. Sec. 125 of the Internal Revenue Code allows employers to provide employees with a choice among benefits, including moving otherwise taxable cash compensation to the pre-tax purchase of benefits, without requiring them to include the value of the noncash benefits in their adjusted gross income unless they choose taxable options. Although the percentage of full-time employees in medium and large private establishments who are eligible for cafeteria plans has not increased appreciably, the percentage of employees eligible for freestanding flexible spending accounts (FSAs) nearly tripled between 1988 and 1991. Generally, the proportion of employers sponsoring cafeteria plans or FSAs increases with employer size. Recent surveys show that 27 percent of employers with 1,000 or more employees offered choice-making plans in 1991, 48 percent of firms offered health care FSAs, and 54 percent offered dependent care FSAs, either in conjunction with cafeteria plans or as a stand-alone option. Ten percent of full-time employees in private firms employing 100 or more workers were eligible to participate in cafeteria plans in 1991. Only 5 percent of full-time employees in state and local governments and 1 percent of similar employees in small private establishments were eligible for cafeteria plans in 1990. Recent Bureau of Labor Statistics' surveys show that, among full-time employees, 27 percent in private establishments with 100 or more employees, 28 percent in state and local governments, and 6 percent in small private establishments were eligible to participate in freestanding FSAs. In 1992, 21 percent of eligible employees contributed to a health care FSA, and only 3 percent of eligible employees contributed to a dependent care FSA. Contributions to health care FSAs averaged $651, and those to dependent care FSAs averaged $2,959. National health reform could have a significant impact on these plans if the tax treatment of health benefits is changed. Taxation of health benefits in excess of a standard benefits package would fundamentally reduce the ability to use FSAs.

Sources of health insurance and characteristics of the uninsured. Analysis of the March 1992 Current Population Survey

Eighty-three percent of nonelderly Americans and 99 percent of elderly Americans (aged 65 and over) were covered by either public or private health insurance in 1991, according to EBRI tabulations of the March 1992 Current Population Survey (CPS). The March 1992 CPS is the most recent data available on the number and characteristics of uninsured Americans. In 1991, 16.6 percent of the nonelderly population--or 36.3 million people--were not covered by private health insurance and did not receive publicly financed health assistance. This number compares with 35.7 million in 1990 (16.6 percent), 34.4 million in 1989 (16.1 percent), and 33.6 million in 1988 (15.9 percent). The most important determinant of health insurance is employment. Nearly two-thirds (64 percent) of the nonelderly have employment-based coverage. Workers were much more likely to be covered by group health plans than nonworkers (71 percent versus 40 percent). Even though workers and members of their families were more likely to be covered by health insurance than nonworkers, 85 percent of the uninsured lived in families headed by workers in 1991, primarily because most people lived in families headed by workers. More than 60 percent of uninsured were in families headed by full-year workers with no unemployment. Nearly all persons who were covered by an employment based-plan received at least some contribution to that plan from their employer. The estimated average annual contribution among those receiving a contribution to employee or family plans was $2,129. Although many individuals in poor families are covered by public health plans, that coverage is far from universal. In 1991, only 52 percent of the nonelderly with income below the poverty line were covered by a public plan--49 percent by Medicaid. The number of children who were uninsured in 1991 was 9.5 million, or 14.7 percent of all children, compared with 9.8 million or 15.3 percent of all children in 1990. Twenty-three percent of children were covered by public health insurance, with 21 percent being covered by Medicaid. In 11 states and the District of Columbia, more than 20 percent of the population was uninsured in 1991. These states and their uninsured rates were the District of Columbia (30.3 percent), Texas (25.3 percent), New Mexico (24.5 percent), Louisiana (23.8 percent), Florida (23.5 percent), Mississippi (22.1 percent), Oklahoma (22.1 percent), Nevada (21.8 percent), California (21.7 percent),Arizona (21.1 percent), Alabama (20.6 percent), and Idaho (20.6 percent).

Parental age, genetic mutation, and cerebral palsy

Parental age and birth order were studied in 251 patients with cerebral palsy. No parental age or birth order effects were observed in spastic quadriplegia or diplegia, but a paternal age effect was detected in those with athetoid/dystonic cerebral palsy and congenital hemiplegia. These observations indicate that some cases of athetoid/dystonic or hemiplegic cerebral palsy might arise by fresh dominant genetic mutation.

The offspring of people with cerebral palsy

To test a hypothesis that a placental deficit as a possible cause of CP might be transmitted, 88 people with congenital CP were contacted by questionnaire and letters. They had had 122 children, 93 per cent of whom were reported to be normal. The frequency of miscarriages and toxaemia was normal. 5 per cent of the mothers had had emergency caesarean sections. Three mothers also had minor malformations. The mean gestational age of the children was 38.8 weeks and their mean birthweight was 3295g. The mean birthweight of the mothers born preterm was 984g and that of their babies was 3244g. Two of the 122 children had diplegia, four had malformations, one had trisomy 18 and there was one stillbirth.

DNA methylation inhibits transcription of procollagen alpha 2(I) promoters

Our previous studies have demonstrated that a 2-[N-(acetoxyacetyl)amino]fluorene-transformed rat epithelial-like cell line, W8, contains a transcriptionally inactive alpha 2(I) gene with a hypermethylated promoter/first-exon region. We have cloned the rat promoter/first-exon region (-211 to +207) from W8 cells and their parent cell line, K16, which expresses alpha 2(I) collagen. There were no sequence differences between the clones from the two cell lines, indicating that a mutation was not responsible for transcriptional inhibition. The alpha 2(I) rat promoters were cloned upstream of the chloramphenicol acetyltransferase gene. Both constructs were equally active in both cell lines, suggesting that trans-activating factors for alpha 2(I) transcription are present in W8 cells. Finally, methylation of plasmids at all CpG sites with SssI methylase completely inhibited transcription using alpha 2(I) promoters, but methylation did not inhibit simian-virus-40 promoter-driven transcription. Certain methylation sites partially inhibit promoter activity. An HhaI methylation site inhibited transcriptional activity of the alpha 2(I) promoter 8-fold, whereas methylation at the HpaII site in the rat alpha 2(I) promoter did not decrease transcriptional activity. This provides further evidence that methylation at specific sites in the collagen alpha 2(I) promoter is responsible for the inactivation of transcription in W8 cells.

Pnemostasis of injured lung in rabbits with gelatin-resorcinol formaldehyde-glutaraldehyde tissue adhesive

Peripheral bronchopulmonary fistulas, or parenchymal air leaks, may occasionally be resistant to conventional suture or stapling techniques. In such instances, the tissue is poor and the associated morbidity of a persistent leak will be the greatest. We tested a previously described tissue adhesive compounded from gelatin resorcinol and polymerized at the time of application with a glutaraldehyde-formaldehyde mixture. We evaluated the ability of the adhesive to seal incisional air leaks acutely in the lungs of rabbits under conditions of positive intratracheal pressure and persistent ventilation. We also tested the efficacy of the glue at intervals after compounding to assess the shelf life of this nonproprietary formula. We established a technique for application of this adhesive and demonstrated its ability to decrease consistently the magnitude of air leaks, while generally providing complete pneumostasis in the presence of clinically relevant positive pressure ventilation. We conclude that this material can be prepared months in advance of its occasional use as an effective means of dealing with parenchymal air leaks encountered at operation.

Leptomeningeal carcinomatosis: a report of 3 cases and review of the literature

Once thought to be rare, leptomeningeal carcinomatosis from systemic cancer is becoming more common as cancer patients are living longer. Lung, breast and malignant melanoma comprise the majority of solid tumor cases with this condition. The hallmark of the disease and the differential diagnosis are discussed. Only the identification of malignant cells in the cerebrospinal fluid provides as clear-cut diagnosis. Biochemical markers, thus far, cannot substitute for a positive cytology, but may aid in the diagnosis. We report and discuss 3 cases of complete biochemical and radiological assessment and variable degree of aggressiveness of treatment. Better control of the systemic cancer may result in prolongation of life.

Dyskinetic and dystonic cerebral palsy and birth

Two hundred and nineteen cases of the dyskinetic and dystonic forms of cerebral palsy which were seen in the course of three decades at a single clinic have been analysed. Fifty-seven patients had kernicterus. In the remaining 162, 71% of whom were born at term, birthweight was below the expected mean in two-thirds. There was no relationship between birth weight, or abnormal birth, or asphyxia, and the ultimate clinical severity of the children. We conclude that abnormal birth and asphyxia are not direct causes of the cerebral damage, but are expressions of a pre-existing condition resulting in susceptibility to the stress of birth, whether it is normal or abnormal.

Proto-oncogene activation in liver tumors of hepatocarcinogenesis-resistant strains of mice

Activation of the ras family of oncogenes occurs frequently in liver tumors of the B6C3F1 mouse, a strain which is highly sensitive to hepatocarcinogenesis. Many other mouse strains are much more resistant to hepatocarcinogenesis; the aim of this study was to determine the frequency and pattern of oncogene activation in spontaneous and chemically induced liver tumors of three such strains, the C57BL/6J, the C57BL/6 x DBA/2 F1 hybrid (B6D2F1) and the C57BL/6 x Balb/c F1 hybrid (B6BCF1). The C57BL/6, DBA/2 and Balb/c strains are all relatively resistant to spontaneous hepatocarcinogenesis (1.5-3.6% of animals develop liver tumors in 2 years); with regard to chemically induced hepatocarcinogenesis the Balb/c is highly resistant, the C57BL/6 has low susceptibility and the DBA/2 has low to moderate susceptibility. The nude mouse tumorigenicity assay was used to search for activated oncogenes in 15 C57BL/6J liver tumors induced by a single neonatal dose of vinyl carbamate (VC, 0.15 mumol/g body weight). Three tumors contained H-ras genes activated by point mutations at codon 61 and one contained a non-ras oncogene. The polymerase chain reaction and allele-specific oligonucleotide hybridization were used to study H-ras mutations in spontaneous and VC-induced tumors from all three strains of mice. The frequency of H-ras codon 61 mutations in tumors induced by 0.15 mumol/g body weight VC in the C57BL/6J mouse (5/37) was similar to that in spontaneous tumors (2/9); surprisingly, tumors induced by a lower dose of VC (0.03 mumol/g body weight) had a higher frequency of H-ras mutations (12/28). The frequencies of H-ras activation detected in VC (0.03 mumol/g body weight)-induced tumors from the two F1 hybrids studied differed markedly. Only one VC-induced B6BCF1 tumor contained a mutated H-ras gene (1/10), whereas the majority of B6D2F1 tumors contained such mutations (23/33). Several spontaneous B6D2F1 liver tumors contained H-ras codon 61 mutations (6/15). Thus, H-ras activation frequency does not determine susceptibility to hepatocarcinogenesis in inbred mice and their F1 hybrids, since a relatively high frequency of H-ras mutations was observed in two resistant strains and a low frequency was found in the other strain.

Differential expression of N-myc in phenotypically distinct subclones of a human neuroblastoma cell line

Neuroblastomas are malignant childhood neoplasms that arise from derivatives of the neural crest. We report the characterization of a new neuroblastoma cell line, designated NBL-W, derived from the primary tumor of a patient with stage IVS disease (S. L. Cohn, C. V. Herst, H. S. Maurer, and S. T. Rosen, J. Clin. Oncol., 5: 1441-1444, 1987) according to the criteria of Evans [A. E. Evans, G. J. D'Angio, and J. Randolf, Cancer (Phila.), 27: 374-378, 1971]. Neurite-bearing (N) and substrate-adherent (S) cell lines have been subcloned from the parent line. N and S cells can interconvert, and both cell types label with the neural crest cell surface marker antibody, HNK-1. Cells in the subcloned lines and in the parent line have been shown by Southern blot analysis to contain approximately 100 copies of the N-myc gene. Cytogenetic analysis shows a homogeneously staining region present on chromosome 19. Although these subclones are of identical genotype, the S cells express lower amounts of N-myc mRNA and protein as compared to the N cells. N cells express several neuronal proteins including the neurotransmitter-processing enzymes tyrosine hydroxylase and dopamine beta-hydroxylase, the neuronal intermediate filament proteins peripherin and NF66/alpha-internexin, and the neural cell adhesion molecule. S cells generally lack neuronal markers but express the mesenchymal intermediate filament protein vimentin, and a small subset of the S cells express glial fibrillary acidic protein. Some S cells were labeled weakly with neural cell adhesion molecule antibody; others were negative. S cells did not express the glial marker S-100 or a melanocyte marker, tyrosinase. Thus, S cells express the neural crest marker HNK-1 but do not express a set of antigens characteristic of any known cell type derived from the neural crest. These results are consistent with the suggestion that differential N-myc expression may be involved in the interconversion of N and S cells but indicate that the S cell phenotype need not represent a highly differentiated neural crest derivative.

Ovarian hormones enhance 2,3,7,8-tetrachlorodibenzo-p-dioxin-mediated increases in cell proliferation and preneoplastic foci in a two-stage model for rat hepatocarcinogenesis

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a potent hepatocarcinogen in rodents. However, liver tumor incidence is increased by TCDD in female Sprague-Dawley rats but not male rats in chronic carcinogen bioassays. Our studies have investigated this finding by evaluating histological and biochemical parameters in a two-stage model for hepatocarcinogenesis in female Sprague-Dawley rats (intact and ovariectomized), using diethylnitrosamine (DEN) as the initiating agent and TCDD as the promoting agent. Increases in gamma-glutamyl transpeptidase-positive foci were greater in intact female rats than in ovariectomized (OVX) animals. For example, in intact rats receiving both DEN and TCDD, the percentage of liver occupied by gamma-glutamyl transpeptidase-positive foci was 0.37, compared to 0.08 in OVX rats. Values for intact or OVX rats receiving either DEN or TCDD only were 0.04 or less. Similar results were obtained when using placental glutathione S-transferase to detect hepatic preneoplastic lesions. Cell proliferation data, obtained using bromodeoxyuridine in osmotic minipumps, were consistent with preneoplastic foci data in that the hepatocyte labeling index was increased in DEN/TCDD intact rats but not in DEN/TCDD OVX rats. Analysis of data from individual animals revealed a strong correlation (P less than 0.01) between cell proliferation and placental glutathione S-transferase-positive foci/cm3 in liver. These findings did not reflect effects of ovariectomy on TCDD tissue distribution, since livers of OVX rats contained more TCDD than livers of intact rats, although both groups of rats received a dose of 1.4 micrograms TCDD/kg once every 2 weeks for 30 weeks. Hepatic cytochrome P-450d (IA2) was induced approximately 6-8-fold in all TCDD-treated groups, and the magnitude of induction was not influenced by ovariectomy. This cytochrome efficiently catalyzes metabolism of 17 beta-estradiol to catechol estrogens. Our data suggest that ovarian hormones (probably estrogen) play a significant role in the hepatocarcinogenic actions of TCDD.

Correlation of hepatocellular proliferation with hepatocarcinogenicity induced by the mutagenic noncarcinogen:carcinogen pair--2,6- and 2,4-diaminotoluene

2,4-Diaminotoluene (2,4-DAT) and 2,6-diaminotoluene (2,6-DAT) are equally genotoxic in the Ames/Salmonella assay and are both readily absorbed, metabolized, and excreted and metabolites of both compounds are mutagenic with metabolic activation. However, there are marked differences in the results of chronic rodent bioassays with these two compounds. 2,4-DAT is a potent hepatocarcinogen whereas 2,6-DAT failed to produce an increased incidence of tumors in any tissue even when administered at a dose higher than that of 2,4-DAT. In an effort to elucidate the source of these apparently discordant results, the present studies were designed to determine the effects of these two chemicals on cell proliferation in the liver when administered at the dose levels comparable to those used in the original bioassays. This study utilized repeated oral dosing, osmotic minipumps to deliver bromodeoxyuridine (BrDU) for 8 days, and immunohistochemistry to quantitate BrDU incorporation into hepatic DNA, CCl4 (0.4 ml/rat, single ip dose) or vehicle control groups were included as positive and negative controls, respectively. The degree of cell proliferation was quantified by the labeling index from at least 1000 hepatocytes. Results from the control studies indicate that approximately 1.1% of the hepatocytes from vehicle-treated animals replicated during the exposure period whereas approximately 50% replicated in the positive controls. The carcinogen 2,4-DAT produced a dose-dependent increase in cell proliferation of approximately 10% and 20% in livers of animals exposed to 12.5 and 25.0 mg/kg/day, respectively, whereas the noncarcinogen 2,6-DAT produced no increase in cell turnover compared to vehicle control following treatment with 25.0 or 50.0 mg/kg/day. These results indicate a positive correlation between increased cell proliferation and hepatocarcinogenesis induced by these two isomers of diaminetoluene.

Aluminum accumulation during treatment with aluminum hydroxide and dialysis in children and young adults with chronic renal disease

BACKGROUND

The control of hyperphosphatemia is a major clinical problem in patients with chronic renal failure receiving regular dialysis treatment. Despite continuing concern about aluminum toxicity, aluminum-containing antacids are still used in many of these patients as phosphate-binding agents. Although maximal acceptable doses of aluminum hydroxide have been recommended, the safety and efficacy of these guidelines have not been evaluated.

METHODS

Seventeen children and young adults (mean [+/- SD] age, 14.1 +/- 3.7 years) undergoing regular peritoneal dialysis were randomly assigned to treatment with either aluminum hydroxide (n = 7; maximal dose, 30 mg per kilogram of body weight per day) or calcium carbonate (n = 10; dose range, 2.5 to 12 g per day, according to serum phosphorus levels). Aluminum retention was assessed by serial measurements of plasma aluminum, deferoxamine-infusion tests, and measurements of bone aluminum content during a mean (+/- SD) follow-up of 13 +/- 2 months. The evolution of bone disease was also evaluated.

RESULTS

Plasma aluminum levels and the increment in plasma aluminum after infusion of deferoxamine increased from base-line values in the patients treated with aluminum hydroxide, and aluminum-related bone disease developed in one patient. Serum phosphorus levels remained higher and serum calcium levels lower in the patients receiving aluminum hydroxide than in those receiving calcium carbonate. The skeletal lesions of secondary hyperparathyroidism improved in 7 of 10 patients receiving calcium carbonate but persisted or progressed in 6 of 7 patients given aluminum hydroxide (P less than 0.025).

CONCLUSIONS

Aluminum hydroxide is less effective than calcium carbonate as a phosphate-binding agent for the control of hyperphosphatemia and is associated with aluminum retention in children and young adults with chronic renal failure who are receiving dialysis therapy.

The in vivo manipulation of alcohol-related beliefs in male social drinkers in a naturalistic setting

Earlier research shows that alcohol expectancies are related to alcohol consumption. However, how the alcohol expectancies are related to drinking in a public bar is still unknown. This paper examines this relationship in 10 moderate-heavy male social drinkers attending alternatively to both alcohol dependent and non-dependent cognitive sets of alcohol use. When discussing the alcohol dependent expectancies, these drinkers consumed significantly less alcohol compared with their consumption when discussing non-alcohol dependent expectancies. This group effect was also corroborated by a within-subject analysis of the data. The implications of the relationship between beliefs and drinking behaviour in terms of a cognitive behaviour model of alcohol use are briefly discussed.

Targeting of peritoneum by the small numbers of isogeneic and allogeneic ascites carcinoma cells that infiltrate or attach to peritoneum during ascites growth

In the course of development of an in vivo invasion model, sublines of a series of allogenic and isogeneic carcinoma cell lines have been selected that show enhanced invasion of the peritoneum. It was found that, during the proliferation of tumor cell lines in ascitic form in the abdominal cavity, small numbers of cells infiltrated or firmly adhered to the peritoneum in at least 8/12 of the tumor-host combinations tried. After thorough washing of the peritoneum it was disaggregated by an enzyme mixture, and the resulting mixture of normal and tumor cells was inoculated intraperitoneally. Peritoneal isolations were made serially for 3 to 12 times. In 6 of 8 cases where the isolation produced a stable ascites, the cells showed enhanced peritoneal invasion compared with the parent cell line. The invasion of some of the cell lines was tested in another invasion model consisting of cultured mouse buccal mucosa (9/10 cell lines invaded the explant). In 3/3 cell lines showing enhanced peritoneum invasion in vivo, there was no enhanced invasion of the buccal mucosa. The enhanced peritoneum invasion appears to be tissue specific rather than a general increase in invasion potential. Pairs of high- and low-invasive cell lines were obtained that should be useful for screening for invasion modulating agents using the mouse ascites/peritoneum in vivo model. It is suggested that the method might be generalized to produce various tumor cell lines that target for the normal tissues that are adjacent to proliferating solid or circulating tumors.

C. botulinum neurotoxin types A and E: isolated light chain breaks down into two fragments. Comparison of their amino acid sequences with tetanus neurotoxin

The flaccid paralysis in the neuromuscular disease botulism appears to depend on the coordinated roles of the approximately 50 kDa light and approximately 100 kDa heavy chain subunits of the approximately 150 kDa neurotoxic protein produced by Clostridium botulinum (J. Biol. Chem. (1987) 262, 2660 and Eur. J. Biochem. (1988) 177, 683). We observed that the light chain after separation from its conjugate heavy chain, in the presence of dithiothreitol and 2 M urea, begins to split into approximately 28 and approximately 18 kDa fragments. The other subunit-the approximately 100 kDa heavy chain following its isolation-and the parent approximately 150 kDa dichain neurotoxin do not break down under comparable conditions. This cleavage was examined in the neurotoxin serotypes A and E. The cleavage does not appear to be due to a protease. Partial amino acid sequences established that: i) the approximately 28-kDa and approximately 18-kDa fragments comprise the N- and C-terminal regions of the light chain, respectively; ii) the light chain of the neurotoxin serotypes A and E break down at precise peptide bonds; iii) the peptide bonds cleaved in serotypes A and E are five residues apart; and iv) the portions of the approximately 18 kDa fragments of serotype A and E neurotoxin sequenced so far are highly homologous to the corresponding region of tetanus neurotoxin produced by Clostridium tetani. The partial N-terminal sequence of the approximately 28 kDa fragment matches with the N-terminal sequence of the intact L chain. The 47 residues of the approximately 18-kDa fragment of type A sequenced from its N-terminal are: -Y.E.M.S.G.L.E.V.S.F.E.E.L.R.T.F.G.G.H.D.A.K.F.I.D.S.L.Q.E.N.E.F.R.L.Y.Y .Y. N.K.F.K. D.I.A.S.T.L.-. These align with those of tetanus neurotoxin beginning at its residue #259 (Tyr); the 18 underlined residues of the above 47 residues (i.e. 38%) are identical in positions between the two proteins. The 41 residues sequenced from the approximately 18 kDa fragment of type E botulinum neurotoxin are: -K.G.I.N.I.E.E.F.L. T.F.G.N.N.D.L.N.I.I.T.V.A.Q.Y.N.D.I.Y.T.N.L.L.N.D.Y.R. K.I.A.X.K. L.-.(ABSTRACT TRUNCATED AT 250 WORDS)

Botulinum neurotoxin type A: cleavage of the heavy chain into two halves and their partial sequences

The 145-kDa type A botulinum neurotoxin (NT) is produced by the bacteria Clostridium botulinum (strain, Hall). The heavy (H) and light (L) chains (97- and 53-kDa, respectively) of this protein are linked by at least one disulfide bond. The N- and C-terminal halves of the H chain appear to have different functions in the mechanism of action of the NT [1987) FEBS Lett. 226, 115-120). Well-characterized and highly purified preparations of the two halves of the H chain are needed for such studies. Two different approaches were taken to cut the H chain with trypsin and isolate the fragments. In one method the cleavage products were: (i) 94-kDa fragment made of the L chain linked to the N-terminal half of the H chain (49 kDa) by a disulfide bond(s), and (ii) the C-terminal 44-kDa fragment. The N-terminal half of H chain was separated from the L chain by reducing the disulfide bond(s) linking them and then purified by ion-exchange chromatography. The 1-27 residues of 49-kDa N-terminal half of the H chain were Ala-Leu-Asn-Asp-Leu-Cys-Ile-Lys-Val-Asn-Asn-Trp-Asp-Leu-Phe-Phe-Ser-Pro- Ser-Glu - Asp-Asn-Phe-Thr-Asn-Asp-Leu-. The sequence of the other half of the H chain (44 kDa) was X-Ile-Ile-Asn-Leu-X-Ile-Leu-Asn-Leu-Arg-Tyr-Glu-X-Asn-His-Leu-Ile-Asp-Le u-Lys- X-Tyr-Ala-Ser-. In the second method, the H chain was first separated from the L chain, purified, and then cleaved. One product of cleavage, the 44-kDa fragment, was partially sequenced; the first 25 residues were identical to the sequence of the 44-kDa fragment generated by the first method. The present work also demonstrated that (i) The cysteine residue(s) located on the N-terminal half of the H chain form the -S-S- link(s) with the L chain. (ii) The other half of the H chain (44-kDa fragment, apparently the C-terminal half) is not linked via -S-S- to the L-chain or to the N-terminal half (49-kDa fragment) of the H chain.(ABSTRACT TRUNCATED AT 400 WORDS)

Hyperlipidemia in pediatric patients undergoing peritoneal dialysis

We evaluated serial measurements of serum lipid levels in 68 patients aged 12.6 +/- 4.7 years undergoing treatment with continuous ambulatory peritoneal dialysis/continuous cycling peritoneal dialysis (CAPD/CCPD). Fasting mean levels of triglycerides (TG) and cholesterol (C) were elevated above the 95th percentile of published normal values by 102% and 19%, respectively, at the start of dialysis. Except for a short-term decrease in TG levels at 6 and 9 months, no significant change in mean lipid levels was observed during a follow-up period of 2 years. At initiation of dialysis, elevated TG and C levels were present in 90% and 69% of the patients, respectively. The prevalence of hyperlipidemia (HL) varied between 63% and 88% (TG) and 61% and 93% (C), respectively, during the follow-up period. TG and C levels were not correlated with caloric intake (evaluated in 17 patients), serum albumin levels, treatment modality (CAPD or CCPD), a history of the nephrotic syndrome, or previous treatment with hemodialysis or transplantation. However, a significant inverse correlation was observed between age and serum lipids at the initiation of dialysis treatment and after 1 year (TG: r = -0.40; C: r = -0.44). Our data indicate a high prevalence of HL but no significant change of serum lipid levels during 2 years of treatment with CAPD/CCPD.

Bone disease in pediatric patients undergoing dialysis with CAPD or CCPD

The histologic features of renal osteodystrophy and the prevalence of bone aluminum deposition in children receiving regular dialysis have not been described. Forty-four pediatric patients undergoing continuous ambulatory (CAPD) or cycling (CCPD) peritoneal dialysis had bone biopsies and deferoxamine (DFO) infusion tests; all were receiving oral calcitriol. Osteitis fibrosa (OF) was found in 39%, mild lesions (M) in 25%, normal histology (NH) in 16%, aplastic lesions (AP) in 11%, and osteomalacia (OM) in 9%. Bone surface aluminum (SA) was present by histochemical staining in 10 out of 20 given aluminum-containing phosphate-binding agents and in 0 of 24 treated with calcium carbonate; chi 2 = 15.5, P less than 0.0001. Serum biochemistries and DFO infusion tests failed to predict bone histology, but plasma aluminum levels were markedly elevated and bone aluminum content was highest in patients with OM. Bone formation rate (BFR) correlated with serum parathyroid hormone (PTH), r = 0.55, P less than 0.001; BFR was inversely related to bone aluminum content (r = -0.42, P less than 0.01), even in patients with OF (r = -0.66, P less than 0.05). All patients with SA greater than 30% had normal or reduced BFR when compared to those with SA less than 30%; chi 2 = 12.2, P less than 0.005. Based on SA greater than 30%, six patients were classified as aluminum-related bone disease: three OM, one AP, and two NH. Two-thirds of pediatric patients undergoing CAPD/CCPD have persistent hyperparathyroidism despite treatment with calcitriol, but aluminum can adversely affect BFR when SA exceeds 30% regardless of histologic lesion or serum PTH level.

Acquired cystic kidney disease in children undergoing long-term dialysis

Acquired cystic kidney disease (ACKD) occurs in adult patients undergoing long-term dialysis. Early detection is important because clinically significant hematuria and malignancies are associated with ACKD. We evaluated by magnetic resonance imaging (MRI) and ultrasonography (US) the incidence of ACKD in 15 patients aged 7.3-21.6 years (mean 15.9 years) with non-cystic primary renal disease. Nine patients had been treated with peritoneal dialysis only, and 6 with both hemodialysis and peritoneal dialysis for 24-73 months (mean 37 months). Three patients (20%) had no cysts. In 5 patients (33%) with bilateral multiple cysts, the diagnosis of ACKD was made by MRI and US. In another 5 patients, solitary cysts were localized to one kidney by MRI, and in 2 patients solitary cysts were seen in both kidneys. This study documents that ACKD is not limited to older patients with end-stage renal disease. Early detection of these cysts can be accomplished by MRI and is warranted since 1 patient developed neoplastic tubular changes which can precede tumor formation.

Mechanisms of mitochondrial photosensitization by the cationic dye, N,N-bis(2-ethyl-1,3-dioxylene)kryptocyanine (EDKC): preferential inactivation of complex I in the electron transport chain

We investigated mechanisms of mitochondrial phototoxicity caused by the cationic cyanine dye N,N'-bis(2-ethyl-1,3-dioxylene)kryptocyanine (EDKC), examining the role of the mitochondrial membrane potential on the dye uptake by carcinoma cells in vitro, and both the dark and photosensitizing effects of the dye on the function of isolated mouse liver mitochondria. When human bladder carcinoma cells (EJ) were pretreated with 2,4-dinitrophenol or nigericin, cellular uptake of EDKC decreased or increased, respectively, consistent with dye uptake that is dependent on membrane potentials. In isolated liver mitochondria, during NADH linked substrate oxidation (using glutamate plus malate or beta-hydroxybutyrate as substrates), low concentrations of the dye (0.25-0.5 microM) sensitized mitochondria to illumination with long wavelength light and inhibited both basal and ADP-stimulated respiration. Similar effects were observed during succinate oxidation, but only at higher concentrations of EDKC (greater than 5 microM) and at 10-fold greater light doses. NADH coenzyme Q reductase (Complex I) activity was inhibited by dye with or without light to an extent comparable to the inhibition of glutamate plus malate oxidation. Activity of cytochrome c oxidase, the terminal enzyme in the electron transport chain, was photosensitized with high dye doses (greater than 5 microM) and light, but the extent of inhibition was much less than the inhibition of respiration with succinate as substrate. ATP synthetase (F0F1 ATPase) activity was minimally affected by 4.0 microM EDKC with or without 24 J/cm2 light. We conclude that at low concentrations of dye, respiratory Complex I is a primary target for EDKC dark and light-induced toxicities. If Complex I is bypassed by using succinate as a respiratory substrate, the mitochondria can tolerate much higher dye concentrations and light doses.

Genetic and antigenic differences of serologically indistinguishable leptospires of serovar hardjo

Pathogenic leptospires of serovar hardjo isolated from North American cattle were compared genetically and antigenically to reference strain hardjoprajitno of the Sejroe serogroup. Guanine-plus-cytosine (G+C) contents were determined for the genomes, and microscopic agglutination, Western blotting (immunoblotting), and immunoprecipitation were used to characterize antigenic relatedness. Major differences were demonstrated between the isolates and the reference strain. The G+C content of the reference strain was calculated to be approximately 34 +/- 1%, and those of the isolates were calculated at 39 +/- 1%. Antigenic differences between the isolates and the reference strain were identified by using rabbit immune serum raised against a hardjo isolate exhaustively adsorbed with hardjoprajitno whole and sonicated cells. Western blot analysis and immunoprecipitation using this adsorbed serum revealed antigens apparently unique for the hardjo isolates. Microscopic agglutination with the adsorbed rabbit serum did not agglutinate hardjoprajitno when diluted 1:2 but agglutinated bovine isolates to a 1:32 dilution. Bovine antiserum raised against the isolates was also used to identify antigens by immunoprecipitation.

An experimental microcomputer controlled system for synchronized pulsating anti-gravity suit

An experimental system to deliver synchronized external pressure pulsations to the lower body is described in this technical note. The system is designed using a microcomputer with a real time interface and an electro-pneumatic subsystem capable of delivering pressure pulses to a modified anti-G suit at a fast rate. It is versatile, containing many options for synchronizing, phasing and sequencing of the pressure pulsations and controlling the pressure level in the suit bladders. Details of its software and hardware are described along with the results of initial testing in a Dynamic Flight Simulator on human volunteers.

Strategies for selective cancer photochemotherapy: antibody-targeted and selective carcinoma cell photolysis

A principle objective in chemotherapy is the development of modalities capable of selectively destroying malignant cells while sparing normal tissues. One new approach to selective photochemotherapy, antibody-targeted photolysis (ATPL) uses photosensitizers (PS) coupled to monoclonal antibodies (MAbs) which bind to cell surface antigens on malignant cells. Selective destruction of human T leukemia cells (HBP-ALL) was accomplished by coupling the efficient PS chlorin e(6) to an anti-T cell MAb using dextran carriers. Conjugates with chlorin: MAb ratios of 30:1 retained > 85% MA b binding activity, and had a quantum yield for singlet oxygen production of 0.7 +/- 0.1, the same as that of free chlorin e(6). Cell killing was dependent on the doses of both MAb-PS and 630-670 nm light and occurred only in target cell populations which bound the MAb. On the order of 10(10) singlet oxygen molecules were necessary to kill a cell. A second approach to specific photochemotherapy, selective carcinoma cell photolysis (SCCP), relies on preferential accumulation of certain cationic PS by carcinoma cell mitochondria. We have evaluated several classes of cationic dyes, and in the case of N,N'-bis-(2-ethyl-1,3-dioxolane)-kryptocyanine (EDKC) and some of its analogs, have demonstrated highly selective killing of human squamous cell, bladder and colon carcinoma cells in vitro. In isolated mitochondria, EDKC uptake and fluorescence depended on membrane potential, and the dye specifically photosensitized damage to Complex I in the electron transport chain. N,N'-bis-(2-ethyl-1,3-dioxolane)-kryptocyanine and some of its analogs accumulated within subcutaneous xenografts of human tumors in nude mice with tumor:skin ratios > 8. Photoirradiation caused significant inhibition of tumor growth, without cutaneous phototoxicity.

Intramitochondrial dyes allow selective in vitro photolysis of carcinoma cells

Carcinoma cell mitochondria preferentially accumulate and retain certain cationic dyes to a much greater extent than most normal cells. Thus, they can potentially serve as targets for highly selective photochemotherapy. We evaluated 10 rhodamine and cyanine dyes as carcinoma-specific mitochondrial photosensitizers in vitro. The most effective, N,N'-bis(2-ethyl-1,3-dioxolane)kryptocyanine (EDKC), caused marked, light-dependent killing of human bladder, squamous, and colon carcinoma cell lines after 30-min incubations at 1-0.01 microM but was minimally toxic to human keratinocytes and to normal monkey kidney epithelial cells (CV-1). Carcinoma cell phototoxicity was proportional to the amount of dye incorporated by the different cell lines. Selective killing ratios were 70-1000 for 0.1 microM dye and light doses of 100-175 J/cm2 between 680 and 720 nm.

Free fatty acid metabolism and obesity in man: in vivo in vitro comparisons

We have examined the relationship of free fatty acid (FFA) turnover and lipid oxidation rates in vivo to the size of body triglyceride stores and compared these findings with the in vitro lipolytic rates of isolated abdominal fat cells. The studies were performed in 20 Pima Indian women 18 to 35 years of age, both lean and obese. FFA turnover rate was measured using a 1-14C-palmitate infusion, lipid oxidation rate by indirect calorimetry using a ventilated hood, body composition by underwater weighing with correction for residual lung volume, and fat cell lipolytic rates in vitro by published methods. Both FFA turnover and lipid oxidation rates, expressed per kg of body fat, decreased with increasing degree of obesity (as measured by percent body fat) (r = -0.90, and r = -0.75, P less than or equal to 0.0001, respectively). In contrast, the rate of lipolysis determined in vitro, expressed per kg of fat, increased with increasing degree of obesity (r = 0.58, P less than 0.01). A ratio of FFA turnover/lipolysis, which directly compares these in vivo and in vitro measurements, decreased significantly with increases in the degree of obesity (r = -0.81, P less than or equal to 0.0001). Furthermore, there were no positive correlations between the measures of in vivo FFA metabolism and in vitro lipolysis when both were expressed per fat mass, per fat cell number, or per fat cell surface area. The in vivo data also demonstrated that lipid oxidation could only account for 50% of the FFA disappearance rate. While lipid oxidation rate adjusted to the metabolic size increased with increasing plasma FFA concentration (r = 0.75, P less than 0.0003), the nonoxidative component of the FFA turnover failed to increase with increases in plasma FFA concentration (P = 0.5). We conclude that FFA is not available in vivo in proportion to the size of the triglyceride stores. The reason for this is not due to an inability of fat cells to release their stored triglyceride as assessed in vitro. Hence, in vitro measurements of fat cell lipolysis cannot be used to directly predict in vivo FFA metabolism. The large nonoxidative FFA disposal is likely to be important in the regulation of plasma FFA concentrations.

Effects of oral calcium carbonate on control of serum phosphorus and changes in plasma aluminum levels after discontinuation of aluminum-containing gels in children receiving dialysis

Orally administered calcium carbonate was evaluated as a phosphate binding agent in 15 children, ages 0.6 to 17.2 years, receiving maintenance dialysis. Changes in plasma aluminum concentration were assessed after discontinuation of treatment with aluminum-containing gels. The mean daily dose of calcium carbonate was 5.1 +/- 2.5 gm (384 +/- 315 mg/kg/day), and correlated inversely with body weight (r = 0.72, P less than 0.01) and age (r = 0.71, P less than 0.01). Mean serum calcium, phosphorus, and bicarbonate values were unchanged throughout the study. Plasma aluminum concentration fell from 90 +/- 51 to 34 +/- 22 micrograms/L (P less than 0.005). Dietary phosphorus intakes were 44 +/- 21 and 42 +/- 19 mg/kg/day during the control period and at the end of the study, respectively. Transitory hypercalcemia was the only side effect in 92% of the patients. In none of the patients did uncontrolled hyperphosphatemia, metabolic alkalosis, diarrhea, or symptoms or signs of hypercalcemia develop. Our data indicate that calcium carbonate is an effective phosphate binding agent in children receiving dialysis, and should be used in lieu of aluminum-containing gels in young children with renal failure.

Immediate ascites conversion of mammary tumors induced in NYLR/Nya mice by 7,12-dimethylbenz-[a] anthracene and urethane feeding and by forced breeding

Intragastric feeding of dimethylbenz-[a]anthracene in corn oil together with urethane in the drinking water and forced breeding were successful in rapidly inducing (2-4 months) mammary tumors (adenoacanthomas) in inbred NYLR/Nya mice, which have a low incidence of spontaneous breast tumors and of other tumors. The tumors could be quickly and permanently transformed to an ascites form by intraperitoneal inoculation of enzyme-dissociated cells and subsequent serial passage of free cells. Only 10 (3 in some cases) serial passages were required, thus conveniently providing multiple isogeneic carcinoma cell lines in this strain of mice. Some tumor cell lines proliferated strongly in the abdominal cavity even on the first passage.

Correlation of histopathologic evidence of disease activity with the presence of immunoglobulin-containing cells in the colons of patients with inflammatory bowel disease

Immunofluorescence of formalin-fixed, paraffin-embedded tissues was performed to study the plasma cell population in 114 colonic specimens from 58 patients. Correlation of the histopathologic stage of disease activity with the isotypes and numbers of immunoglobulin-containing cells in the lamina propria demonstrated highly significant (P less than 0.001) increases in the mean numbers of IgG- (18-fold), IgA- (twofold) and IgM- (sixfold) containing cells in specimens from patients with active inflammatory bowel disease as compared with control specimens. Increased numbers of immunoglobulin-containing cells were uncommon in inactive inflammatory bowel disease and in reactive mucosa. No deposition of immunoglobulin-containing immune complexes was found at any stage of disease activity. These findings suggest that immune complex-mediated damage does not play a major role in the epithelial damage in inflammatory bowel disease. In future studies, it will be of importance to determine whether the antibody from immunoglobulin-containing cells seen in patients with inflammatory bowel disease can effect damage via an antibody-dependent cell-mediated cytotoxicity mechanism.